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# Americans and the Great War, 1914-1919
## American Isolationism and the European Origins of War
Unlike his immediate predecessors, President Woodrow Wilson had planned to shrink the role of the United States in foreign affairs. He believed that the nation needed to intervene in international events only when there was a moral imperative to do so. But as Europe’s political situation grew dire, it became increasingly difficult for Wilson to insist that the conflict growing overseas was not America’s responsibility. Germany’s war tactics struck most observers as morally reprehensible, while also putting American free trade with the Entente at risk. Despite campaign promises and diplomatic efforts, Wilson could only postpone American involvement in the war.
### WOODROW WILSON’S EARLY EFFORTS AT FOREIGN POLICY
When Woodrow Wilson took over the White House in March 1913, he promised a less expansionist approach to American foreign policy than Theodore Roosevelt and William Howard Taft had pursued. Wilson did share the commonly held view that American values were superior to those of the rest of the world, that democracy was the best system to promote peace and stability, and that the United States should continue to actively pursue economic markets abroad. But he proposed an idealistic foreign policy based on morality, rather than American self-interest, and felt that American interference in another nation’s affairs should occur only when the circumstances rose to the level of a moral imperative.
Wilson appointed former presidential candidate William Jennings Bryan, a noted anti-imperialist and proponent of world peace, as his Secretary of State. Bryan undertook his new assignment with great vigor, encouraging nations around the world to sign “cooling off treaties,” under which they agreed to resolve international disputes through talks, not war, and to submit any grievances to an international commission. Bryan also negotiated friendly relations with Colombia, including a $25 million apology for Roosevelt’s actions during the Panamanian Revolution, and worked to establish effective self-government in the Philippines in preparation for the eventual American withdrawal. Even with Bryan’s support, however, Wilson found that it was much harder than he anticipated to keep the United States out of world affairs (). In reality, the United States was interventionist in areas where its interests—direct or indirect—were threatened.
Wilson’s greatest break from his predecessors occurred in Asia, where he abandoned Taft’s “dollar diplomacy,” a foreign policy that essentially used the power of U.S. economic dominance as a threat to gain favorable terms. Instead, Wilson revived diplomatic efforts to keep Japanese interference there at a minimum. But as World War I, also known as the Great War, began to unfold, and European nations largely abandoned their imperialistic interests in order to marshal their forces for self-defense, Japan demanded that China succumb to a Japanese protectorate over their entire nation. In 1917, William Jennings Bryan’s successor as Secretary of State, Robert Lansing, signed the Lansing-Ishii Agreement, which recognized Japanese control over the Manchurian region of China in exchange for Japan’s promise not to exploit the war to gain a greater foothold in the rest of the country.
Furthering his goal of reducing overseas interventions, Wilson had promised not to rely on the Roosevelt Corollary, Theodore Roosevelt’s explicit policy that the United States could involve itself in Latin American politics whenever it felt that the countries in the Western Hemisphere needed policing. Once president, however, Wilson again found that it was more difficult to avoid American interventionism in practice than in rhetoric. Indeed, Wilson intervened more in Western Hemisphere affairs than either Taft or Roosevelt. In 1915, when a revolution in Haiti resulted in the murder of the Haitian president and threatened the safety of New York banking interests in the country, Wilson sent over three hundred U.S. Marines to establish order. Subsequently, the United States assumed control over the island’s foreign policy as well as its financial administration. One year later, in 1916, Wilson again sent marines to Hispaniola, this time to the Dominican Republic, to ensure prompt payment of a debt that nation owed. In 1917, Wilson sent troops to Cuba to protect American-owned sugar plantations from attacks by Cuban rebels; this time, the troops remained for four years.
Wilson’s most noted foreign policy foray prior to World War I focused on Mexico, where rebel general Victoriano Huerta had seized control from a previous rebel government just weeks before Wilson’s inauguration. Wilson refused to recognize Huerta’s government, instead choosing to make an example of Mexico by demanding that they hold democratic elections and establish laws based on the moral principles he espoused. Officially, Wilson supported Venustiano Carranza, who opposed Huerta’s military control of the country. When American intelligence learned of a German ship allegedly preparing to deliver weapons to Huerta’s forces, Wilson ordered the U.S. Navy to land forces at Veracruz to stop the shipment.
On April 22, 1914, a fight erupted between the U.S. Navy and Mexican troops, resulting in nearly 150 deaths, nineteen of them American. Although Carranza’s faction managed to overthrow Huerta in the summer of 1914, most Mexicans—including Carranza—had come to resent American intervention in their affairs. Carranza refused to work with Wilson and the U.S. government, and instead threatened to defend Mexico’s mineral rights against all American oil companies established there. Wilson then turned to support rebel forces who opposed Carranza, most notably Pancho Villa (). However, Villa lacked the strength in number or weapons to overtake Carranza; in 1915, Wilson reluctantly authorized official U.S. recognition of Carranza’s government.
As a postscript, an irate Pancho Villa turned against Wilson, and on March 9, 1916, led a fifteen-hundred-man force across the border into New Mexico, where they attacked and burned the town of Columbus. Over one hundred people died in the attack, seventeen of them American. Wilson responded by sending General John Pershing into Mexico to capture Villa and return him to the United States for trial. With over eleven thousand troops at his disposal, Pershing marched three hundred miles into Mexico before an angry Carranza ordered U.S. troops to withdraw from the nation. Although reelected in 1916, Wilson reluctantly ordered the withdrawal of U.S. troops from Mexico in 1917, avoiding war with Mexico and enabling preparations for American intervention in Europe. Again, as in China, Wilson’s attempt to impose a moral foreign policy had failed in light of economic and political realities.
### WAR ERUPTS IN EUROPE
When a Serbian nationalist, Gavrilo Princip, murdered the Archduke Franz Ferdinand of the Austro-Hungarian Empire on June 28, 1914, the underlying forces that led to World War I had already long been in motion and seemed, at first, to have little to do with the United States. At the time, the events that pushed Europe from ongoing tensions into war seemed very far away from U.S. interests. For nearly a century, European nations had negotiated a series of alliance treaties to secure themselves against their rivals. The two main alliances that existed in Europe before the outbreak of World War I were the Triple Entente and the Triple Alliance. The former bound France, Great Britain, and Russia into a “moral obligation” to defend each other in case of war. The latter was a stricter mutual defense alliance that included Germany, Austria-Hungary, and Italy. With the outbreak of war, these alliances transformed into the two opposing sides in the conflict. The Triple Alliance became the Central powers and added the Ottoman Empire and Bulgaria. Italy declared neutrality and eventually joined the opposing side, the Allied powers, which formed around the rump of the Triple Entente and over the course of the war added additional major countries like the United States and Japan. A series of “side treaties” likewise entangled the larger European powers to protect several smaller ones should war break out.
At the same time that European nations committed each other to defense pacts, they jockeyed for power over empires overseas and invested heavily in large, modern militaries. Dreams of empire and military supremacy fueled an era of nationalism that was particularly pronounced in the newer nations of Germany and Italy. Some in Serbia were also swept up in the nationalist fervor of the age and sought to extend Serbia’s territorial claims over all ethnic Serbs in southeastern Europe. In 1914, a group of these Serbian nationalist assassinated the Austro-Hungarian archduke as part of their fight to achieve this goal. After the assassination, Austria-Hungary pointed the finger at Serbia and issued a list of harsh demands. When Serbia failed to accede to Austro-Hungarian demands in the wake of the archduke’s murder, Austria-Hungary declared war on Serbia with the confidence that it had the backing of Germany. This action, in turn, brought Russia into the conflict, due to a treaty in which they had agreed to defend Serbia. Germany followed suit by declaring war on Russia, fearing that Russia and France would seize this opportunity to move on Germany if it did not take the offensive. The eventual German invasion of Belgium drew Great Britain into the war, followed by the attack of the Ottoman Empire on Russia. By the end of August 1914, it seemed as if Europe had dragged the entire world into war.
The Great War was unlike any war that came before it. Whereas in previous European conflicts, troops typically faced each other on open battlefields, World War I saw new military technologies that turned war into a conflict of prolonged trench warfare. Both sides used new artillery, tanks, airplanes, machine guns, barbed wire, and, eventually, poison gas: weapons that strengthened defenses and turned each military offense into barbarous sacrifices of thousands of lives with minimal territorial advances in return. By the end of the war, the total military death toll was ten million, as well as another million civilian deaths attributed to military action, and another six million civilian deaths caused by famine, disease, or other related factors.
One terrifying new piece of technological warfare was the German unterseeboot—an “undersea boat” or U-boat. By early 1915, in an effort to break the British naval blockade of Germany and turn the tide of the war, the Germans dispatched a fleet of these submarines around Great Britain to attack both merchant and military ships. The U-boats acted in direct violation of international law, attacking without warning from beneath the water instead of surfacing and permitting the surrender of civilians or crew. By 1918, German U-boats had sunk nearly five thousand vessels. Of greatest historical note was the attack on the British passenger ship, RMS Lusitania, on its way from New York to Liverpool on May 7, 1915. The German Embassy in the United States had announced that this ship would be subject to attack for its cargo of ammunition: an allegation that later proved accurate. Nonetheless, almost 1,200 civilians died in the attack, including 128 Americans. The attack horrified the world, galvanizing support in England and beyond for the war (). This attack, more than any other event, would test President Wilson’s desire to stay out of what had been a largely European conflict.
### THE CHALLENGE OF NEUTRALITY
Despite the loss of American lives on the Lusitania, President Wilson stuck to his path of neutrality in Europe’s escalating war: in part out of moral principle, in part as a matter of practical necessity, and in part for political reasons. Few Americans wished to participate in the devastating battles that ravaged Europe, and Wilson did not want to risk losing his reelection by ordering an unpopular military intervention. Wilson’s “neutrality” did not mean isolation from all warring factions, but rather open markets for the United States and continued commercial ties with all belligerents. For Wilson, the conflict did not reach the threshold of a moral imperative for U.S. involvement; it was largely a European affair involving numerous countries with whom the United States wished to maintain working relations. In his message to Congress in 1914, the president noted that “Every man who really loves America will act and speak in the true spirit of neutrality, which is the spirit of impartiality and fairness and friendliness to all concerned.”
Wilson understood that he was already looking at a difficult reelection bid. He had only won the 1912 election with 42 percent of the popular vote, and likely would not have been elected at all had Roosevelt not come back as a third-party candidate to run against his former protégée Taft. Wilson felt pressure from all different political constituents to take a position on the war, yet he knew that elections were seldom won with a campaign promise of “If elected, I will send your sons to war!” Facing pressure from some businessmen and other government officials who felt that the protection of America’s best interests required a stronger position in defense of the Allied forces, Wilson agreed to a “preparedness campaign” in the year prior to the election. This campaign included the passage of the National Defense Act of 1916, which more than doubled the size of the army to nearly 225,000, and the Naval Appropriations Act of 1916, which called for the expansion of the U.S. fleet, including battleships, destroyers, submarines, and other ships.
As the 1916 election approached, the Republican Party hoped to capitalize on the fact that Wilson was making promises that he would not be able to keep. They nominated Charles Evans Hughes, a former governor of New York and sitting U.S. Supreme Court justice at the time of his nomination. Hughes focused his campaign on what he considered Wilson’s foreign policy failures, but even as he did so, he himself tried to walk a fine line between neutrality and belligerence, depending on his audience. In contrast, Wilson and the Democrats capitalized on neutrality and campaigned under the slogan “Wilson—he kept us out of war.” The election itself remained too close to call on election night. Only when a tight race in California was decided two days later could Wilson claim victory in his reelection bid, again with less than 50 percent of the popular vote. Despite his victory based upon a policy of neutrality, Wilson would find true neutrality a difficult challenge. Several different factors pushed Wilson, however reluctantly, toward the inevitability of American involvement.
A key factor driving U.S. engagement was economics. Great Britain was the country’s most important trading partner, and the Allies as a whole relied heavily on American imports from the earliest days of the war forward. Specifically, the value of all exports to the Allies quadrupled from $750 million to $3 billion in the first two years of the war. At the same time, the British naval blockade meant that exports to Germany all but ended, dropping from $350 million to $30 million. Likewise, numerous private banks in the United States made extensive loans—in excess of $500 million—to England. J. P. Morgan’s banking interests were among the largest lenders, due to his family’s connection to the country.
Another key factor complicating the decision to go to war was the deep ethnic divisions between native-born Americans and more recent immigrants. For those of Anglo-Saxon descent, the nation’s historic and ongoing relationship with Great Britain was paramount, but many Irish-Americans resented British rule over their place of birth and opposed support for the world’s most expansive empire. Millions of Jewish immigrants had fled anti-Semitic pogroms in Tsarist Russia and would have supported any nation fighting that authoritarian state. German Americans saw their nation of origin as a victim of British and Russian aggression and a French desire to settle old scores, whereas emigrants from Austria-Hungary and the Ottoman Empire were mixed in their sympathies for the old monarchies or ethnic communities that these empires suppressed. For interventionists, this lack of support for Great Britain and its allies among recent immigrants only strengthened their conviction.
Germany’s use of submarine warfare also played a role in challenging U.S. neutrality. After the sinking of the Lusitania, and the subsequent August 30 sinking of another British liner, the Arabic, Germany had promised to restrict their use of submarine warfare. Specifically, they promised to surface and visually identify any ship before they fired, as well as permit civilians to evacuate targeted ships. Instead, in February 1917, Germany intensified their use of submarines in an effort to end the war quickly before Great Britain’s naval blockade starved them out of food and supplies.
The German high command wanted to continue unrestricted warfare on all Atlantic traffic, including unarmed American freighters, in order to devastate the British economy and secure a quick and decisive victory. Their goal: to bring an end to the war before the United States could intervene and tip the balance in this grueling war of attrition. In February 1917, a German U-boat sank the American merchant ship, the Laconia, killing two passengers, and, in late March, quickly sunk four more American ships. These attacks increased pressure on Wilson from all sides, as government officials, the general public, and both Democrats and Republicans urged him to declare war.
The final element that led to American involvement in World War I was the so-called Zimmermann telegram. British intelligence intercepted and decoded a top-secret telegram from German foreign minister Arthur Zimmermann to the German ambassador to Mexico, instructing the latter to invite Mexico to join the war effort on the German side, should the United States declare war on Germany. It further went on to encourage Mexico to invade the United States if such a declaration came to pass, as Mexico’s invasion would create a diversion and permit Germany a clear path to victory. In exchange, Zimmermann offered to return to Mexico land that was previously lost to the United States in the Mexican-American War, including Arizona, New Mexico, and Texas ().
The likelihood that Mexico, weakened and torn by its own revolution and civil war, could wage war against the United States and recover territory lost in the Mexican-American war with Germany’s help was remote at best. But combined with Germany’s unrestricted use of submarine warfare and the sinking of American ships, the Zimmermann telegram made a powerful argument for a declaration of war. The outbreak of the Russian Revolution in February and abdication of Tsar Nicholas II in March raised the prospect of democracy in the Eurasian empire and removed an important moral objection to entering the war on the side of the Allies. On April 2, 1917, Wilson asked Congress to declare war on Germany. Congress debated for four days, and several senators and congressmen expressed their concerns that the war was being fought over U.S. economic interests more than strategic need or democratic ideals. When Congress voted on April 6, fifty-six voted against the resolution, including the first woman ever elected to Congress, Representative Jeannette Rankin. This was the largest “no” vote against a war resolution in American history.
### Section Summary
President Wilson had no desire to embroil the United States in the bloody and lengthy war that was devastating Europe. His foreign policy, through his first term and his campaign for reelection, focused on keeping the United States out of the war and involving the country in international affairs only when there was a moral imperative to do so. After his 1916 reelection, however, the free trade associated with neutrality proved impossible to secure against the total war strategies of the belligerents, particularly Germany’s submarine warfare. Ethnic ties to Europe meant that much of the general public was more than happy to remain neutral. Wilson’s reluctance to go to war was mirrored in Congress, where fifty-six voted against the war resolution. The measure still passed, however, and the United States went to war against the wishes of many of its citizens.
### Review Questions
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# Americans and the Great War, 1914-1919
## The United States Prepares for War
Wilson knew that the key to America’s success in war lay largely in its preparation. With both the Allied and enemy forces entrenched in battles of attrition, and supplies running low on both sides, the United States needed, first and foremost, to secure enough men, money, food, and supplies to be successful. The country needed to first supply the basic requirements to fight a war, and then work to ensure military leadership, public support, and strategic planning.
### THE INGREDIENTS OF WAR
The First World War was, in many ways, a war of attrition, and the United States needed a large army to help the Allies. In 1917, when the United States declared war on Germany, the U.S. Army ranked seventh in the world in terms of size, with an estimated 200,000 enlisted men. In contrast, at the outset of the war in 1914, the German force included 4.5 million men, and the country ultimately mobilized over eleven million soldiers over the course of the entire war.
To compose a fighting force, Congress passed the Selective Service Act in 1917, which initially required all men aged twenty-one through thirty to register for the draft (). In 1918, the act was expanded to include all men between eighteen and forty-five. Through a campaign of patriotic appeals, as well as an administrative system that allowed men to register at their local draft boards rather than directly with the federal government, over ten million men registered for the draft on the very first day. By the war’s end, twenty-two million men had registered for the U.S. Army draft. Five million of these men were actually drafted, another 1.5 million volunteered, and over 500,000 additional men signed up for the navy or marines. In all, two million men participated in combat operations overseas. Among the volunteers were also twenty thousand women, a quarter of whom went to France to serve as nurses or in clerical positions.
But the draft also provoked opposition, and almost 350,000 eligible Americans refused to register for military service. About 65,000 of these defied the conscription law as conscientious objectors, mostly on the grounds of their deeply held religious beliefs. Such opposition was not without risks, and whereas most objectors were never prosecuted, those who were found guilty at military hearings received stiff punishments: Courts handed down over two hundred prison sentences of twenty years or more, and seventeen death sentences.
With the size of the army growing, the U.S. government next needed to ensure that there were adequate supplies—in particular food and fuel—for both the soldiers and the home front. Concerns over shortages led to the passage of the Lever Food and Fuel Control Act, which empowered the president to control the production, distribution, and price of all food products during the war effort. Using this law, Wilson created both a Fuel Administration and a Food Administration. The Fuel Administration, run by Harry Garfield, created the concept of “fuel holidays,” encouraging civilian Americans to do their part for the war effort by rationing fuel on certain days. Garfield also implemented “daylight saving time” for the first time in American history, shifting the clocks to allow more productive daylight hours. Herbert Hoover coordinated the Food Administration, and he too encouraged volunteer rationing by invoking patriotism. With the slogan “food will win the war,” Hoover encouraged “Meatless Mondays,” “Wheatless Wednesdays,” and other similar reductions, with the hope of rationing food for military use ().
Wilson also created the War Industries Board, run by Bernard Baruch, to ensure adequate military supplies. The War Industries Board had the power to direct shipments of raw materials, as well as to control government contracts with private producers. Baruch used lucrative contracts with guaranteed profits to encourage several private firms to shift their production over to wartime materials. For those firms that refused to cooperate, Baruch’s government control over raw materials provided him with the necessary leverage to convince them to join the war effort, willingly or not.
As a way to move all the personnel and supplies around the country efficiently, Congress created the U.S. Railroad Administration. Logistical problems had led trains bound for the East Coast to get stranded as far away as Chicago. To prevent these problems, Wilson appointed William McAdoo, the Secretary of the Treasury, to lead this agency, which had extraordinary war powers to control the entire railroad industry, including traffic, terminals, rates, and wages.
Almost all the practical steps were in place for the United States to fight a successful war. The only step remaining was to figure out how to pay for it. The war effort was costly—with an eventual price tag in excess of $32 billion by 1920—and the government needed to finance it. The Liberty Loan Act allowed the federal government to sell liberty bonds to the American public, extolling citizens to “do their part” to help the war effort and bring the troops home. The government ultimately raised $23 billion through liberty bonds. Additional monies came from the government’s use of federal income tax revenue, which was made possible by the passage of the Sixteenth Amendment to the U.S. Constitution in 1913. With the financing, transportation, equipment, food, and men in place, the United States was ready to enter the war. The next piece the country needed was public support.
### CONTROLLING DISSENT
Although all the physical pieces required to fight a war fell quickly into place, the question of national unity was another concern. The American public was strongly divided on the subject of entering the war. While many felt it was the only choice, others protested strongly, feeling it was not America’s war to fight. Wilson needed to ensure that a nation of diverse immigrants, with ties to both sides of the conflict, thought of themselves as American first, and their home country’s nationality second. To do this, he initiated a propaganda campaign, pushing the “America First” message, which sought to convince Americans that they should do everything in their power to ensure an American victory, even if that meant silencing their own criticisms.
The Wilson administration created the Committee of Public Information under director George Creel, a former journalist, just days after the United States declared war on Germany. Creel employed artists, speakers, writers, and filmmakers to develop a propaganda machine. The goal was to encourage all Americans to make sacrifices during the war and, equally importantly, to hate all things German (). Through efforts such as the establishment of “loyalty leagues” in ethnic immigrant communities, Creel largely succeeded in molding an anti-German sentiment around the country. The result? Some schools banned the teaching of the German language and some restaurants refused to serve frankfurters, sauerkraut, or hamburgers, instead serving “liberty dogs with liberty cabbage” and “liberty sandwiches.” Symphonies refused to perform music written by German composers. The hatred of Germans grew so widespread that, at one point, at a circus, audience members cheered when, in an act gone horribly wrong, a Russian bear mauled a German animal trainer (whose ethnicity was more a part of the act than reality).
In addition to its propaganda campaign, the U.S. government also tried to secure broad support for the war effort with repressive legislation. The Trading with the Enemy Act of 1917 prohibited individual trade with an enemy nation and banned the use of the postal service for disseminating any literature deemed treasonous by the postmaster general. That same year, the Espionage Act prohibited giving aid to the enemy by spying, or espionage, as well as any public comments that opposed the American war effort. Under this act, the government could impose fines and imprisonment of up to twenty years. The Sedition Act, passed in 1918, prohibited any criticism or disloyal language against the federal government and its policies, the U.S. Constitution, the military uniform, or the American flag. More than two thousand persons were charged with violating these laws, and many received prison sentences of up to twenty years. Immigrants faced deportation as punishment for their dissent. Not since the Alien and Sedition Acts of 1798 had the federal government so infringed on the freedom of speech of loyal American citizens.
In the months and years after these laws came into being, over one thousand people were convicted for their violation, primarily under the Espionage and Sedition Acts. More importantly, many more war critics were frightened into silence. One notable prosecution was that of Socialist Party leader Eugene Debs, who received a ten-year prison sentence for encouraging draft resistance, which, under the Espionage Act, was considered “giving aid to the enemy.” Prominent Socialist Victor Berger was also prosecuted under the Espionage Act and subsequently twice denied his seat in Congress, to which he had been properly elected by the citizens of Milwaukee, Wisconsin. One of the more outrageous prosecutions was that of a film producer who released a film about the American Revolution: Prosecutors found the film seditious, and a court convicted the producer to ten years in prison for portraying the British, who were now American allies, as the obedient soldiers of a monarchical empire.
State and local officials, as well as private citizens, aided the government’s efforts to investigate, identify, and crush subversion. Over 180,000 communities created local “councils of defense,” which encouraged members to report any antiwar comments to local authorities. This mandate encouraged spying on neighbors, teachers, local newspapers, and other individuals. In addition, a larger national organization—the American Protective League—received support from the Department of Justice to spy on prominent dissenters, as well as open their mail and physically assault draft evaders.
Understandably, opposition to such repression began mounting. In 1917, Roger Baldwin formed the National Civil Liberties Bureau—a forerunner to the American Civil Liberties Union, which was founded in 1920—to challenge the government’s policies against wartime dissent and conscientious objection. In 1919, the case of Schenck v. United States went to the U.S. Supreme Court to challenge the constitutionality of the Espionage and Sedition Acts. The case concerned Charles Schenck, a leader in the Socialist Party of Philadelphia, who had distributed fifteen thousand leaflets, encouraging young men to avoid conscription. The court ruled that during a time of war, the federal government was justified in passing such laws to quiet dissenters. The decision was unanimous, and in the court’s opinion, Justice Oliver Wendell Holmes wrote that such dissent presented a “clear and present danger” to the safety of the United States and the military, and was therefore justified. He further explained how the First Amendment right of free speech did not protect such dissent, in the same manner that a citizen could not be freely permitted to yell “fire!” in a crowded theater, due to the danger it presented. Congress ultimately repealed most of the Espionage and Sedition Acts in 1921, and several who were imprisoned for violation of those acts were then quickly released. But the Supreme Court’s deference to the federal government’s restrictions on civil liberties remained a volatile topic in future wars.
### Section Summary
Wilson might have entered the war unwillingly, but once it became inevitable, he quickly moved to use federal legislation and government oversight to put into place the conditions for the nation’s success. First, he sought to ensure that all logistical needs—from fighting men to raw materials for wartime production—were in place and within government reach. From legislating rail service to encouraging Americans to buy liberty loans and “bring the boys home sooner,” the government worked to make sure that the conditions for success were in place. Then came the more nuanced challenge of ensuring that a country of immigrants from both sides of the conflict fell in line as Americans, first and foremost. Aggressive propaganda campaigns, combined with a series of restrictive laws to silence dissenters, ensured that Americans would either support the war or at least stay silent. While some conscientious objectors and others spoke out, the government efforts were largely successful in silencing those who had favored neutrality.
### Review Questions
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# Americans and the Great War, 1914-1919
## A New Home Front
The lives of all Americans, whether they went abroad to fight or stayed on the home front, changed dramatically during the war. Restrictive laws censored dissent at home, and the armed forces demanded unconditional loyalty from millions of volunteers and conscripted soldiers. For organized labor, women, and African Americans in particular, the war brought changes to the prewar status quo. Some White women worked outside of the home for the first time, whereas others, like African American men, found that they were eligible for jobs that had previously been reserved for White men. African American women, too, were able to seek employment beyond the domestic servant jobs that had been their primary opportunity. These new options and freedoms were not easily erased after the war ended.
### NEW OPPORTUNITIES BORN FROM WAR
After decades of limited involvement in the challenges between management and organized labor, the need for peaceful and productive industrial relations prompted the federal government during wartime to invite organized labor to the negotiating table. Samuel Gompers, head of the American Federation of Labor (AFL), sought to capitalize on these circumstances to better organize workers and secure for them better wages and working conditions. His efforts also solidified his own base of power. The increase in production that the war required exposed severe labor shortages in many states, a condition that was further exacerbated by the draft, which pulled millions of young men from the active labor force.
Wilson only briefly investigated the longstanding animosity between labor and management before ordering the creation of the National Labor War Board in April 1918. Quick negotiations with Gompers and the AFL resulted in a promise: Organized labor would make a “no-strike pledge” for the duration of the war, in exchange for the U.S. government’s protection of workers’ rights to organize and bargain collectively. The federal government kept its promise and promoted the adoption of an eight-hour workday (which had first been adopted by government employees in 1868), a living wage for all workers, and union membership. As a result, union membership skyrocketed during the war, from 2.6 million members in 1916 to 4.1 million in 1919. In short, American workers received better working conditions and wages, as a result of the country’s participation in the war. However, their economic gains were limited. While prosperity overall went up during the war, it was enjoyed more by business owners and corporations than by the workers themselves. Even though wages increased, inflation offset most of the gains. Prices in the United States increased an average of 15–20 percent annually between 1917 and 1920. Individual purchasing power actually declined during the war due to the substantially higher cost of living. Business profits, in contrast, increased by nearly a third during the war.
### Women in Wartime
For women, the economic situation was complicated by the war, with the departure of wage-earning men and the higher cost of living pushing many toward less comfortable lives. At the same time, however, wartime presented new opportunities for women in the workplace. More than one million women entered the workforce for the first time as a result of the war, while more than eight million working women found higher paying jobs, often in industry. Many women also found employment in what were typically considered male occupations, such as on the railroads (), where the number of women tripled, and on assembly lines. After the war ended and men returned home and searched for work, women were fired from their jobs, and expected to return home and care for their families. Furthermore, even when they were doing men’s jobs, women were typically paid lower wages than male workers, and unions were ambivalent at best—and hostile at worst—to women workers. Even under these circumstances, wartime employment familiarized women with an alternative to a life in domesticity and dependency, making a life of employment, even a career, plausible for women. When, a generation later, World War II arrived, this trend would increase dramatically.
One notable group of women who exploited these new opportunities was the Women’s Land Army of America. First during World War I, then again in World War II, these women stepped up to run farms and other agricultural enterprises, as men left for the armed forces (). Known as Farmerettes, some twenty thousand women—mostly college educated and from larger urban areas—served in this capacity. Their reasons for joining were manifold. For some, it was a way to serve their country during a time of war. Others hoped to capitalize on the efforts to further the fight for women’s suffrage.
Also of special note were the approximately thirty thousand American women who served in the military, as well as a variety of humanitarian organizations, such as the Red Cross and YMCA, during the war. In addition to serving as military nurses (without rank), American women also served as telephone operators in France. Of this latter group, 230 of them, known as “Hello Girls,” were bilingual and stationed in combat areas. Over eighteen thousand American women served as Red Cross nurses, providing much of the medical support available to American troops in France. Close to three hundred nurses died during service. Many of those who returned home continued to work in hospitals and home healthcare, helping wounded veterans heal both emotionally and physically from the scars of war.
### African Americans in the Crusade for Democracy
African Americans also found that the war brought upheaval and opportunity. Black people composed 13 percent of the enlisted military, with 350,000 men serving. Colonel Charles Young of the Tenth Cavalry division served as the highest-ranking African American officer. Black people served in segregated units and suffered from widespread racism in the military hierarchy, often serving in menial or support roles. Some troops saw combat, however, and were commended for serving with valor. The 369th Infantry, for example, known as the Harlem Hellfighters, served on the frontline of France for six months, longer than any other American unit. One hundred seventy-one men from that regiment received the Legion of Merit for meritorious service in combat. The regiment marched in a homecoming parade in New York City, was remembered in paintings (), and was celebrated for bravery and leadership. The accolades given to them, however, in no way extended to the bulk of African Americans fighting in the war.
On the home front, African Americans, like American women, saw economic opportunities increase during the war. During the so-called Great Migration (discussed in a previous chapter), nearly 350,000 African Americans had fled the post-Civil War South for opportunities in northern urban areas. From 1910–1920, they moved north and found work in the steel, mining, shipbuilding, and automotive industries, among others. African American women also sought better employment opportunities beyond their traditional roles as domestic servants. By 1920, over 100,000 women had found work in diverse manufacturing industries, up from 70,000 in 1910.
Despite these opportunities, racism continued to be a major force in both the North and South. Worried that Black veterans would feel empowered to change the status quo of White supremacy, many White people took political, economic, and violent action against them. In a speech on the Senate floor in 1917, Mississippi Senator James K. Vardaman said, “Impress the negro with the fact that he is defending the flag, inflate his untutored soul with military airs, teach him that it is his duty to keep the emblem of the Nation flying triumphantly in the air—it is but a short step to the conclusion that his political rights must be respected.” Several municipalities passed residential codes designed to prohibit African Americans from settling in certain neighborhoods. Race riots also increased in frequency: In 1917 alone, there were race riots in twenty-five cities, including East Saint Louis, where thirty-nine Black people were killed. In the South, White business and plantation owners feared that their cheap workforce was fleeing the region, and used violence to intimidate Black people into staying. According to NAACP statistics, recorded incidences of lynching increased from thirty-eight in 1917 to eighty-three in 1919. Dozens of Black veterans were among the victims. The frequency of these killings did not start to decrease until 1923, when the number of annual lynchings dropped below thirty-five for the first time since the Civil War.
### THE LAST VESTIGES OF PROGRESSIVISM
Across the United States, the war intersected with the last lingering efforts of the Progressives who sought to use the war as motivation for their final push for change. It was in large part due to the war’s influence that Progressives were able to lobby for the passage of the Eighteenth and Nineteenth Amendments to the U.S. Constitution. The Eighteenth Amendment, prohibiting alcohol, and the Nineteenth Amendment, giving women the right to vote, received their final impetus due to the war effort.
Prohibition, as the anti-alcohol movement became known, had been a goal of many Progressives for decades. Organizations such as the Women’s Christian Temperance Union and the Anti-Saloon League linked alcohol consumption with any number of societal problems, and they had worked tirelessly with municipalities and counties to limit or prohibit alcohol on a local scale. But with the war, prohibitionists saw an opportunity for federal action. One factor that helped their cause was the strong anti-German sentiment that gripped the country, which turned sympathy away from the largely German-descended immigrants who ran the breweries. Furthermore, the public cry to ration food and grain—the latter being a key ingredient in both beer and hard alcohol—made prohibition even more patriotic. Congress ratified the Eighteenth Amendment in January 1919, with provisions to take effect one year later. Specifically, the amendment prohibited the manufacture, sale, and transportation of intoxicating liquors. It did not prohibit the drinking of alcohol, as there was a widespread feeling that such language would be viewed as too intrusive on personal rights. However, by eliminating the manufacture, sale, and transport of such beverages, drinking was effectively outlawed. Shortly thereafter, Congress passed the Volstead Act, translating the Eighteenth Amendment into an enforceable ban on the consumption of alcoholic beverages, and regulating the scientific and industrial uses of alcohol. The act also specifically excluded from prohibition the use of alcohol for religious rituals ().
Unfortunately for proponents of the amendment, the ban on alcohol did not take effect until one full year following the end of the war. Almost immediately following the war, the general public began to oppose—and clearly violate—the law, making it very difficult to enforce. Doctors and druggists, who could prescribe whisky for medicinal purposes, found themselves inundated with requests. In the 1920s, organized crime and gangsters like Al Capone would capitalize on the persistent demand for liquor, making fortunes in the illegal trade. A lack of enforcement, compounded by an overwhelming desire by the public to obtain alcohol at all costs, eventually resulted in the repeal of the law in 1933.
The First World War also provided the impetus for another longstanding goal of some reformers: universal suffrage. Supporters of equal rights for women pointed to Wilson’s rallying cry of a war “to make the world safe for democracy,” as hypocritical, saying he was sending American boys to die for such principles while simultaneously denying American women their democratic right to vote (). Carrie Chapman Catt, president of the National American Women Suffrage Movement, capitalized on the growing patriotic fervor to point out that every woman who gained the vote could exercise that right in a show of loyalty to the nation, thus offsetting the dangers of draft-dodgers or naturalized Germans who already had the right to vote.
Alice Paul, of the National Women’s Party, organized more radical tactics, bringing national attention to the issue of women’s suffrage by organizing protests outside the White House and, later, hunger strikes among arrested protesters.
African American suffragists, who had been active in the movement for decades, faced discrimination from their White counterparts. Some White leaders justified this treatment based on the concern that promoting Black women would erode public support. For example, leaders of the NAWSA convention 1911 disallowed an amendment adding race as an element of the organization's platform based on the idea that White men would oppose the entire movement. But overt racism played a significant role, as well. In response, Black suffragists had formed what would become the National Association of Colored Women Clubs. Its most prominent leaders, Josephine St. Pierre Ruffin and Mary Church Terrell, led the organization in its efforts for women's rights, ending lynchings, and raising money for social services such as orphanages and homes for the elderly. The NACWC did not always align with the NAWSA even though they were moving toward the same general goals. At some points, the organizations came into direct confrontation. During the suffrage parade in 1913, Black members were told to march at the rear of the line. Ida B. Wells-Barnett, a prominent voice for equality, first asked her local delegation to oppose this segregation; they refused. Not to be dismissed, Wells-Barnett waited in the crowd until the Illinois delegation passed by, then stepped onto the parade route and took her place among them. By the end of the war, the abusive treatment of suffragist hunger-strikers in prison, women’s important contribution to the war effort, and the arguments of his suffragist daughter Jessie Woodrow Wilson Sayre moved President Wilson to understand women’s right to vote as an ethical mandate for a true democracy. He began urging congressmen and senators to adopt the legislation. The amendment finally passed in June 1919, and the states ratified it by August 1920. Specifically, the Nineteenth Amendment prohibited all efforts to deny the right to vote on the basis of sex. It took effect in time for American women to vote in the presidential election of 1920.
### Section Summary
The First World War remade the world for all Americans, whether they served abroad or stayed at home. For some groups, such as women and Black people, the war provided opportunities for advancement. As soldiers went to war, women and African Americans took on jobs that had previously been reserved for White men. In return for a no-strike pledge, workers gained the right to organize. Many of these shifts were temporary, however, and the end of the war came with a cultural expectation that the old social order would be reinstated.
Some reform efforts also proved short-lived. President Wilson’s wartime agencies managed the wartime economy effectively but closed immediately with the end of the war (although they reappeared a short while later with the New Deal). While patriotic fervor allowed Progressives to pass prohibition, the strong demand for alcohol made the law unsustainable. Women’s suffrage, however, was a Progressive movement that came to fruition in part because of the circumstances of the war, and unlike prohibition, it remained.
### Review Questions
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# Americans and the Great War, 1914-1919
## From War to Peace
The American role in World War I was brief but decisive. While millions of soldiers went overseas, and many thousands paid with their lives, the country’s involvement was limited to the very end of the war. In fact, the peace process, with the international conference and subsequent ratification process, took longer than the time U.S. soldiers were “in country” in France. For the Allies, American reinforcements came at a decisive moment in their defense of the western front, where a final offensive had exhausted German forces. For the United States, and for Wilson’s vision of a peaceful future, the fighting was faster and more successful than what was to follow.
### WINNING THE WAR
When the United States declared war on Germany in April 1917, the Allied forces were close to exhaustion. Great Britain and France had already indebted themselves heavily in the procurement of vital American military supplies. Now, facing a possible defeat, a British delegation to Washington, DC, requested immediate troop reinforcements to boost Allied spirits and help crush German fighting morale, which was already weakened by short supplies on the frontlines and hunger on the home front. Wilson agreed and immediately sent 200,000 American troops in June 1917. These soldiers were placed in “quiet zones” while they trained and prepared for combat.
By March 1918, the Germans had won the war on the eastern front. The Russian Revolution of the previous year had not only toppled the hated regime of Tsar Nicholas II but also ushered in a civil war from which the Bolshevik faction of Communist revolutionaries under the leadership of Vladimir Lenin emerged victorious. Weakened by war and internal strife, and eager to build a new Soviet Union, Russian delegates agreed to a generous peace treaty with Germany. Thus emboldened, Germany quickly moved upon the Allied lines, causing both the French and British to ask Wilson to forestall extensive training to U.S. troops and instead commit them to the front immediately. Although wary of the move, Wilson complied, ordering the commander of the American Expeditionary Force, General John “Blackjack” Pershing, to offer U.S. troops as replacements for the Allied units in need of relief. By May 1918, Americans were fully engaged in the war ().
In a series of battles along the front that took place from May 28 through August 6, 1918, including the battles of Cantigny, Chateau Thierry, Belleau Wood, and the Second Battle of the Marne, American forces alongside the British and French armies succeeded in repelling the German offensive. The Battle of Cantigny, on May 28, was the first American offensive in the war: In less than two hours that morning, American troops overran the German headquarters in the village, thus convincing the French commanders of their ability to fight against the German line advancing towards Paris. The subsequent battles of Chateau Thierry and Belleau Wood proved to be the bloodiest of the war for American troops. At the latter, faced with a German onslaught of mustard gas, artillery fire, and mortar fire, U.S. Marines attacked German units in the woods on six occasions—at times meeting them in hand-to-hand and bayonet combat—before finally repelling the advance. The U.S. forces suffered 10,000 casualties in the three-week battle, with almost 2,000 killed in total and 1,087 on a single day. Brutal as they were, they amounted to small losses compared to the casualties suffered by France and Great Britain. Still, these summer battles turned the tide of the war, with the Germans in full retreat by the end of July 1918 ().
By the end of September 1918, over one million U.S. soldiers staged a full offensive into the Argonne Forest. By November—after nearly forty days of intense fighting—the German lines were broken, and their military command reported to German Emperor Kaiser Wilhelm II of the desperate need to end the war and enter into peace negotiations. Facing civil unrest from the German people in Berlin, as well as the loss of support from his military high command, Kaiser Wilhelm abdicated his throne on November 9, 1918, and immediately fled by train to the Netherlands. Two days later, on November 11, 1918, Germany and the Allies declared an immediate armistice, thus bring the fighting to a stop and signaling the beginning of the peace process.
When the armistice was declared, a total of 117,000 American soldiers had been killed and 206,000 wounded. The Allies as a whole suffered over 5.7 million military deaths, primarily Russian, British, and French men. The Central powers suffered four million military deaths, with half of them German soldiers. The total cost of the war to the United States alone was in excess of $32 billion, with interest expenses and veterans’ benefits eventually bringing the cost to well over $100 billion. Economically, emotionally, and geopolitically, the war had taken an enormous toll.
### THE BATTLE FOR PEACE
While Wilson had been loath to involve the United States in the war, he saw the country’s eventual participation as justification for America’s involvement in developing a moral foreign policy for the entire world. The “new world order” he wished to create from the outset of his presidency was now within his grasp. The United States emerged from the war as the predominant world power. Wilson sought to capitalize on that influence and impose his moral foreign policy on all the nations of the world.
### The Paris Peace Conference
As early as January 1918—a full five months before U.S. military forces fired their first shot in the war, and eleven months before the actual armistice—Wilson announced his postwar peace plan before a joint session of Congress. Referring to what became known as the Fourteen Points, Wilson called for openness in all matters of diplomacy and trade, specifically, free trade, freedom of the seas, an end to secret treaties and negotiations, promotion of self-determination of all nations, and more. In addition, he called for the creation of a League of Nations to promote the new world order and preserve territorial integrity through open discussions in place of intimidation and war.
As the war concluded, Wilson announced, to the surprise of many, that he would attend the Paris Peace Conference himself, rather than ceding to the tradition of sending professional diplomats to represent the country (). His decision influenced other nations to follow suit, and the Paris conference became the largest meeting of world leaders to date in history. For six months, beginning in December 1918, Wilson remained in Paris to personally conduct peace negotiations. Although the French public greeted Wilson with overwhelming enthusiasm, other delegates at the conference had deep misgivings about the American president’s plans for a “peace without victory.” Specifically, Great Britain, France, and Italy sought to obtain some measure of revenge against Germany for drawing them into the war, to secure themselves against possible future aggressions from that nation, and also to maintain or even strengthen their own colonial possessions. Great Britain and France in particular sought substantial monetary reparations, as well as territorial gains, at Germany’s expense. Japan also desired concessions in Asia, whereas Italy sought new territory in Europe. Finally, the threat posed by a Bolshevik Russia under Vladimir Lenin, and more importantly, the danger of revolutions elsewhere, further spurred on these allies to use the treaty negotiations to expand their territories and secure their strategic interests, rather than strive towards world peace.
In the end, the Treaty of Versailles that officially concluded World War I resembled little of Wilson’s original Fourteen Points. The Japanese, French, and British succeeded in carving up many of Germany’s colonial holdings in Africa and Asia. The dissolution of the Ottoman Empire created new nations under the quasi-colonial rule of France and Great Britain, such as Iraq and Palestine. France gained much of the disputed territory along their border with Germany, as well as passage of a “war guilt clause” that demanded Germany take public responsibility for starting and prosecuting the war that led to so much death and destruction. Great Britain led the charge that resulted in Germany agreeing to pay reparations in excess of $33 billion to the Allies. As for Bolshevik Russia, Wilson had agreed to send American troops to their northern region to protect Allied supplies and holdings there, while also participating in an economic blockade designed to undermine Lenin’s power. This move would ultimately have the opposite effect of galvanizing popular support for the Bolsheviks.
The sole piece of the original Fourteen Points that Wilson successfully fought to keep intact was the creation of a League of Nations. At a covenant agreed to at the conference, all member nations in the League would agree to defend all other member nations against military threats. Known as Article X, this agreement would basically render each nation equal in terms of power, as no member nation would be able to use its military might against a weaker member nation. Ironically, this article would prove to be the undoing of Wilson’s dream of a new world order.
### Ratification of the Treaty of Versailles
Although the other nations agreed to the final terms of the Treaty of Versailles, Wilson’s greatest battle lay in the ratification debate that awaited him upon his return. As with all treaties, this one would require two-thirds approval by the U.S. Senate for final ratification, something Wilson knew would be difficult to achieve. Even before Wilson’s return to Washington, Senator Henry Cabot Lodge, chairman of the Senate Foreign Relations Committee that oversaw ratification proceedings, issued a list of fourteen reservations he had regarding the treaty, most of which centered on the creation of a League of Nations. An isolationist in foreign policy issues, Lodge feared that Article X would require extensive American intervention, as more countries would seek her protection in all controversial affairs. But on the other side of the political spectrum, interventionists argued that Article X would impede the United States from using her rightfully attained military power to secure and protect America’s international interests.
Wilson’s greatest fight was with the Senate, where most Republicans opposed the treaty due to the clauses surrounding the creation of the League of Nations. Some Republicans, known as Irreconcilables, opposed the treaty on all grounds, whereas others, called Reservationists, would support the treaty if sufficient amendments were introduced that could eliminate Article X. In an effort to turn public support into a weapon against those in opposition, Wilson embarked on a cross-country railway speaking tour. He began travelling in September 1919, and the grueling pace, after the stress of the six months in Paris, proved too much. Wilson fainted following a public event on September 25, 1919, and immediately returned to Washington. There he suffered a debilitating stroke, leaving his second wife Edith Wilson in charge as de facto president for a period of about six months.
Frustrated that his dream of a new world order was slipping away—a frustration that was compounded by the fact that, now an invalid, he was unable to speak his own thoughts coherently—Wilson urged Democrats in the Senate to reject any effort to compromise on the treaty. As a result, Congress voted on, and defeated, the originally worded treaty in November. When the treaty was introduced with “reservations,” or amendments, in March 1920, it again fell short of the necessary margin for ratification. As a result, the United States never became an official signatory of the Treaty of Versailles. Nor did the country join the League of Nations, which shattered the international authority and significance of the organization. Although Wilson received the Nobel Peace Prize in October 1919 for his efforts to create a model of world peace, he remained personally embarrassed and angry at his country’s refusal to be a part of that model. As a result of its rejection of the treaty, the United States technically remained at war with Germany until July 21, 1921, when it formally came to a close with Congress’s quiet passage of the Knox-Porter Resolution.
### Section Summary
American involvement in World War I came late. Compared to the incredible carnage endured by Europe, the United States’ battles were brief and successful, although the appalling fighting conditions and significant casualties made it feel otherwise to Americans, both at war and at home. For Wilson, victory in the fields of France was not followed by triumphs in Versailles or Washington, DC, where his vision of a new world order was summarily rejected by his allied counterparts and then by the U.S. Congress. Wilson had hoped that America’s political influence could steer the world to a place of more open and tempered international negotiations. His influence did lead to the creation of the League of Nations, but concerns at home impeded the process so completely that the United States never signed the treaty that Wilson worked so hard to create.
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# Americans and the Great War, 1914-1919
## Demobilization and Its Difficult Aftermath
As world leaders debated the terms of the peace, the American public faced its own challenges at the conclusion of the First World War. Several unrelated factors intersected to create a chaotic and difficult time, just as massive numbers of troops rapidly demobilized and came home. Racial tensions, a terrifying flu epidemic, anticommunist hysteria, and economic uncertainty all combined to leave many Americans wondering what, exactly, they had won in the war. Adding to these problems was the absence of President Wilson, who remained in Paris for six months, leaving the country leaderless. The result of these factors was that, rather than a celebratory transition from wartime to peace and prosperity, and ultimately the Jazz Age of the 1920s, 1919 was a tumultuous year that threatened to tear the country apart.
### DISORDER AND FEAR IN AMERICA
After the war ended, U.S. troops were demobilized and rapidly sent home. One unanticipated and unwanted effect of their return was the emergence of a new strain of influenza that medical professionals had never before encountered. Within months of the war’s end, over twenty million Americans fell ill from the flu (). Eventually, 675,000 Americans died before the disease mysteriously ran its course in the spring of 1919. Worldwide, recent estimates suggest that 500 million people suffered from this flu strain, with as many as fifty million people dying. Throughout the United States, from the fall of 1918 to the spring of 1919, fear of the flu gripped the country. Americans avoided public gatherings, children wore surgical masks to school, and undertakers ran out of coffins and burial plots in cemeteries. Hysteria grew as well, and instead of welcoming soldiers home with a postwar celebration, people hunkered down and hoped to avoid contagion.
Another element that greatly influenced the challenges of immediate postwar life was economic upheaval. As discussed above, wartime production had led to steady inflation; the rising cost of living meant that few Americans could comfortably afford to live off their wages. When the government’s wartime control over the economy ended, businesses slowly recalibrated from the wartime production of guns and ships to the peacetime production of toasters and cars. Public demand quickly outpaced the slow production, leading to notable shortages of domestic goods. As a result, inflation skyrocketed in 1919. By the end of the year, the cost of living in the United States was nearly double what it had been in 1916. Workers, facing a shortage in wages to buy more expensive goods, and no longer bound by the no-strike pledge they made for the National War Labor Board, initiated a series of strikes for better hours and wages. In 1919 alone, more than four million workers participated in a total of nearly three thousand strikes: both records within all of American history.
In addition to labor clashes, race riots shattered the peace at the home front. The race riots that had begun during the Great Migration only grew in postwar America. White soldiers returned home to find Black workers in their former jobs and neighborhoods, and were committed to restoring their position of White supremacy. Black soldiers returned home with a renewed sense of justice and strength, and were determined to assert their rights as men and as citizens. Meanwhile, southern lynchings continued to escalate, with White mobs burning African Americans at the stake. The mobs often used false accusations of indecency and assault on White women to justify the murders. During the “Red Summer” of 1919, northern cities recorded twenty-five bloody race riots that killed over 250 people. Among these was the Chicago Race Riot of 1919, where a White mob stoned a young Black boy to death because he swam too close to the “White beach” on Lake Michigan. Police at the scene did not arrest the perpetrator who threw the rock. This crime prompted a week-long riot that left twenty-three Black people and fifteen White people dead, as well as millions of dollars’ worth of damage to the city ().
A massacre in Tulsa, Oklahoma, in 1921, turned out even more deadly, with estimates of Black fatalities ranging from fifty to three hundred. Again, the violence arose based on a dubious allegation of assault on a White girl by a Black teenager. After an incendiary newspaper article, a conflict at the courthouse led to ten White and two Black peoples' deaths. A riot ensued, with White groups pursuing Black people as they retreated to the Greenwood section of the city. Both sides were armed, and gunfire and arson continued throughout the night. The next morning, the White groups began an assault on the Black neighborhoods, killing many Black residents and destroying homes and businesses. The Tulsa Massacre (also called the Tulsa Riot, Greenwood Massacre, or Black Wall Street Massacre) was widely reported at the time, but was omitted from many historical recollections, textbooks, and media for decades.
While illness, economic hardship, and racial tensions all came from within, another destabilizing factor arrived from overseas. As revolutionary rhetoric emanating from Bolshevik Russia intensified in 1918 and 1919, a Red Scare erupted in the United States over fear that Communist infiltrators sought to overthrow the American government as part of an international revolution (). When investigators uncovered a collection of thirty-six letter bombs at a New York City post office, with recipients that included several federal, state, and local public officials, as well as industrial leaders such as John D. Rockefeller, fears grew significantly. And when eight additional bombs actually exploded simultaneously on June 2, 1919, including one that destroyed the entrance to U.S. attorney general A. Mitchell Palmer’s house in Washington, the country was convinced that all radicals, no matter what ilk, were to blame. Socialists, Communists, members of the Industrial Workers of the World (Wobblies), and anarchists: They were all threats to be taken down.
Private citizens who considered themselves upstanding and loyal Americans, joined by discharged soldiers and sailors, raided radical meeting houses in many major cities, attacking any alleged radicals they found inside. By November 1919, Palmer’s new assistant in charge of the Bureau of Investigation, J. Edgar Hoover, organized nationwide raids on radical headquarters in twelve cities around the country. Subsequent “Palmer raids” resulted in the arrests of four thousand alleged American radicals who were detained for weeks in overcrowded cells. Almost 250 of those arrested were subsequently deported on board a ship dubbed “the Soviet Ark” ().
### A RETURN TO NORMALCY
By 1920, Americans had failed their great expectations to make the world safer and more democratic. The flu epidemic had demonstrated the limits of science and technology in making Americans less vulnerable. The Red Scare signified Americans’ fear of revolutionary politics and the persistence of violent capital-labor conflicts. And race riots made it clear that the nation was no closer to peaceful race relations either. After a long era of Progressive initiatives and new government agencies, followed by a costly war that did not end in a better world, most of the public sought to focus on economic progress and success in their private lives instead. As the presidential election of 1920 unfolded, the extent of just how tired Americans were of an interventionist government—whether in terms of Progressive reform or international involvement—became exceedingly clear. Republicans, anxious to return to the White House after eight years of Wilson idealism, capitalized on this growing American sentiment to find the candidate who would promise a return to normalcy.
The Republicans found their man in Senator Warren G. Harding from Ohio. Although not the most energetic candidate for the White House, Harding offered what party handlers desired—a candidate around whom they could mold their policies of low taxes, immigration restriction, and noninterference in world affairs. He also provided Americans with what they desired: a candidate who could look and act presidential, and yet leave them alone to live their lives as they wished.
Democratic leaders realized they had little chance at victory. Wilson remained adamant that the election be a referendum over his League of Nations, yet after his stroke, he was in no physical condition to run for a third term. Political in-fighting among his cabinet, most notably between A. Mitchell Palmer and William McAdoo, threatened to split the party convention until a compromise candidate could be found in Ohio governor James Cox. Cox chose, for his vice presidential running mate, the young Assistant Secretary of the Navy, Franklin Delano Roosevelt.
At a time when Americans wanted prosperity and normalcy, rather than continued interference in their lives, Harding won in an overwhelming landslide, with 404 votes to 127 in the Electoral College, and 60 percent of the popular vote. With the war, the flu epidemic, the Red Scare, and other issues behind them, American looked forward to Harding’s inauguration in 1921, and to an era of personal freedoms and hedonism that would come to be known as the Jazz Age.
### Section Summary
The end of a successful war did not bring the kind of celebration the country craved or anticipated. The flu pandemic, economic troubles, and racial and ideological tensions combined to make the immediate postwar experience in the United States one of anxiety and discontent. As the 1920 presidential election neared, Americans made it clear that they were seeking a break from the harsh realities that the country had been forced to face through the previous years of Progressive mandates and war. By voting in President Warren G. Harding in a landslide election, Americans indicated their desire for a government that would leave them alone, keep taxes low, and limit social Progressivism and international intervention.
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# The Jazz Age: Redefining the Nation, 1919-1929
## Introduction
Following the hardships of the immediate postwar era, the United States embarked upon one of the most prosperous decades in history. Mass production, especially of the automobile, increased mobility and fostered new industries. Unemployment plummeted as businesses grew to meet this increased demand. Cities continued to grow and, according to the 1920 census, a majority of the population lived in urban areas of twenty-five hundred or more residents.
Jazz music, movies, speakeasies, and new dances dominated the urban evening scene. Recent immigrants from southern and eastern Europe, many of them Catholic, now participated in the political system. This challenged rural Protestant fundamentalism, even as quota laws sought to limit new immigration patterns. The Ku Klux Klan rose to greater power, as they protested not only the changing role of African Americans but also the growing population of immigrant, Catholic, and Jewish Americans.
This mixture of social, political, economic, and cultural change and conflict gave the decade the nickname the “Roaring Twenties” or the “Jazz Age.” The above illustration (), which graced the cover of F. Scott Fitzgerald’s Tales of the Jazz Age, embodies the popular view of the 1920s as a nonstop party, replete with dancing, music, flappers, and illegal drinking. |
# The Jazz Age: Redefining the Nation, 1919-1929
## Prosperity and the Production of Popular Entertainment
In the 1920s, prosperity manifested itself in many forms, most notably in advancements in entertainment and technology that led to new patterns of leisure and consumption. Movies and sports became increasingly popular and buying on credit or “carrying” the debt allowed for the sale of more consumer goods and put automobiles within reach of average Americans. Advertising became a central institution in this new consumer economy, and commercial radio and magazines turned athletes and actors into national icons.
### MOVIES
The increased prosperity of the 1920s gave many Americans more disposable income to spend on entertainment. As the popularity of “moving pictures” grew in the early part of the decade, “movie palaces,” capable of seating thousands, sprang up in major cities. A ticket for a double feature and a live show cost twenty-five cents; for a quarter, Americans could escape from their problems and lose themselves in another era or world. People of all ages attended the movies with far more regularity than today, often going more than once per week. By the end of the decade, weekly movie attendance swelled to ninety million people.
The silent movies of the early 1920s gave rise to the first generation of movie stars. Rudolph Valentino, the lothario with the bedroom eyes, and Clara Bow, the “It Girl” with sex appeal, filled the imagination of millions of American moviegoers. However, no star captured the attention of the American viewing public more than Charlie Chaplin. This sad-eyed tramp with a moustache, baggy pants, and a cane was the top box office attraction of his time ().
In 1927, the world of the silent movie began to wane with the New York release of the first “talkie”: The Jazz Singer. The plot of this film, which starred Al Jolson, told a distinctively American story of the 1920s. It follows the life of a Jewish man from his boyhood days of being groomed to be the cantor at the local synagogue to his life as a famous and “Americanized” jazz singer. Both the story and the new sound technology used to present it were popular with audiences around the country. It quickly became a huge hit for Warner Brothers, one of the “big five” motion picture studios in Hollywood along with Twentieth Century Fox, RKO Pictures, Paramount Pictures, and Metro-Goldwyn-Mayer.
Southern California in the 1920s, however, had only recently become the center of the American film industry. Film production was originally based in and around New York, where Thomas Edison first debuted the kinetoscope in 1893. But in the 1910s, as major filmmakers like D. W. Griffith looked to escape the cost of Edison’s patents on camera equipment, this began to change. When Griffith filmed In Old California (1910), the first movie ever shot in Hollywood, California, the small town north of Los Angeles was little more than a village. As moviemakers flocked to southern California, not least because of its favorable climate and predictable sunshine, Hollywood swelled with moviemaking activity. By the 1920s, the once-sleepy village was home to a majorly profitable innovative industry in the United States.
### AUTOMOBILES AND AIRPLANES: AMERICANS ON THE MOVE
Cinema was not the only major industry to make great technological strides in this decade. The 1920s opened up new possibilities of mobility for a large percentage of the U.S. population, as automobile manufacturers began to mass produce what had once been a luxury item, and daring aviators both demonstrated and drove advancements in aircraft technology. The most significant innovation of this era was Henry Ford’s Model T Ford, which made car ownership available to the average American.
Ford did not invent the automobile—the Duryea brothers in Massachusetts as well as Gottlieb W. Daimler and Karl Friedrich Benz in Germany were early pioneers. By the early twentieth century, hundreds of car manufacturers existed. However, they all made products that were too expensive for most Americans. Ford’s innovation lay in his focus on using mass production to manufacture automobiles; he revolutionized industrial work by perfecting the assembly line, which enabled him to lower the Model T’s price from $850 in 1908 to $300 in 1924, making car ownership a real possibility for a large share of the population (). As prices dropped, more and more people could afford to own a car. Soon, people could buy used Model Ts for as little as five dollars, allowing students and others with low incomes to enjoy the freedom and mobility of car ownership. By 1929, there were over twenty-three million automobiles on American roads.
The assembly line helped Ford reduce labor costs within the production process by moving the product from one team of workers to the next, each of them completing a step so simple they had to be, in Ford’s words, “no smarter than an ox” (). Ford’s reliance on the moving assembly line, scientific management, and time-motion studies added to his emphasis on efficiency over craftsmanship.
Ford’s emphasis on cheap mass production brought both benefits and disadvantages to its workers. Ford would not allow his workers to unionize, and the boring, repetitive nature of the assembly line work generated a high turnover rate. However, to reduce the turnover rate, he doubled workers’ pay to five dollars a day and standardized the workday to eight hours (a reduction from the norm). Ford’s assembly line also offered greater equality than most opportunities of the time, as he paid White and Black workers equally. Seeking these wages, many African Americans from the South moved to Detroit and other large northern cities to work in factories.
The automobile changed the face of America, both economically and socially. Industries like glass, steel, and rubber processing expanded to keep up with auto production. The oil industry in California, Oklahoma, and Texas expanded, as Americans’ reliance on oil increased and the nation transitioned from a coal-based economy to one driven by petroleum. The need for public roadways required local and state governments to fund a dramatic expansion of infrastructure, which permitted motels and restaurants to spring up and offer new services to millions of newly mobile Americans with cash to spend. With this new infrastructure, new shopping and living patterns emerged, and streetcar suburbs gave way to automobile suburbs as private automobile traffic on public roads began to replace mass transit on trains and trolleys.
The 1920s not only witnessed a transformation in ground transportation but also major changes in air travel. By the mid-1920s, men—as well as some pioneering women like the African American stunt pilot Bessie Coleman ()—had been flying for two decades. But there remained doubts about the suitability of airplanes for long-distance travel. Orville Wright, one of the pioneers of airplane technology in the United States, once famously declared, “No flying machine will ever fly from New York to Paris [because] no known motor can run at the requisite speed for four days without stopping.” However, in 1927, this skepticism was finally put to rest when Charles Lindbergh became the first person to fly solo across the Atlantic Ocean, flying from New York to Paris in thirty-three hours ().
Lindbergh’s flight made him an international hero: the best-known American in the world. On his return, Americans greeted him with a ticker-tape parade—a celebration in which shredded paper thrown from surrounding buildings creates a festive, flurry effect. His flight, which he completed in the monoplane Spirit of St. Louis, seemed like a triumph of individualism in modern mass society and exemplified Americans’ ability to conquer the air with new technology. Following his success, the small airline industry began to blossom, fully coming into its own in the 1930s, as companies like Boeing and Ford developed airplanes designed specifically for passenger air transport. As technologies in engine and passenger compartment design improved, air travel became more popular. In 1934, the number of U.S. domestic air passengers was just over 450,000 annually. By the end of the decade, that number had increased to nearly two million.
Technological innovation influenced more than just transportation. As access to electricity became more common and the electric motor was made more efficient, inventors began to churn out new and more complex household appliances. Newly developed innovations like radios, phonographs, vacuum cleaners, washing machines, and refrigerators emerged on the market during this period. While expensive, new consumer-purchasing innovations like store credit and installment plans made them available to a larger segment of the population. Many of these devices promised to give women—who continued to have primary responsibility for housework—more opportunities to step out of the home and expand their horizons. Ironically, however, these labor-saving devices tended to increase the workload for women by raising the standards of domestic work. With the aid of these tools, women ended up cleaning more frequently, washing more often, and cooking more elaborate meals rather than gaining spare time.
Despite the fact that the promise of more leisure time went largely unfulfilled, the lure of technology as the gateway to a more relaxed lifestyle endured. This enduring dream was a testament to the influence of another growing industry: advertising. The mass consumption of cars, household appliances, ready-to-wear clothing, and processed foods depended heavily on the work of advertisers. Magazines like Ladies’ Home Journal and The Saturday Evening Post became vehicles to connect advertisers with middle-class consumers. Colorful and occasionally provocative print advertisements decorated the pages of these publications and became a staple in American popular culture ().
The form of the advertisements, however, was not new. These colorful print ads were merely the modern incarnations of an advertising strategy that went back to the nineteenth century. The new medium for advertisers in the 1920s, the one that would reach out to consumers in radically new and innovative ways, was radio.
### THE POWER OF RADIO AND THE WORLD OF SPORTS
After being introduced during World War I, radios became a common feature in American homes of the 1920s. Hundreds of radio stations popped up over the decade. These stations developed and broadcasted news, serial stories, and political speeches. Much like print media, advertising space was interspersed with entertainment. Yet, unlike magazines and newspapers, advertisers did not have to depend on the active participation of consumers: Advertisers could reach out to anyone within listening distance of the radio. On the other hand, their broader audience meant that they had to be more conservative and careful not to offend anyone.
The power of radio further sped up the processes of nationalization and homogenization that were previously begun with the wide distribution of newspapers made possible by railroads and telegraphs. Far more effectively than these print media, however, radio created and pumped out American culture onto the airwaves and into the homes of families around the country. Syndicated radio programs like Amos ‘n’ Andy, which began in the late 1920s, entertained listeners around the country—in the case of the popular Amos ‘n’ Andy, it did so with racial stereotypes about African Americans familiar from minstrel shows of the previous century. No longer were small corners of the country separated by their access to information. With the radio, Americans from coast to coast could listen to exactly the same programming. This had the effect of smoothing out regional differences in dialect, language, music, and even consumer taste.
Radio also transformed how Americans enjoyed sports. The introduction of play-by-play descriptions of sporting events broadcast over the radio brought sports entertainment right into the homes of millions. Radio also helped to popularize sports figures and their accomplishments. Jim Thorpe, who grew up in the Sac and Fox Nation in Oklahoma, was known as one of the best athletes in the world: He medaled in the 1912 Olympic Games, played Major League Baseball, and was one of the founding members of the National Football League. Other sports superstars were soon household names. In 1926, Gertrude Ederle became the first woman to swim the English Channel. Helen Wills dominated women’s tennis, winning Wimbledon eight times in the late 1920s (), whereas “Big Bill” Tilden won the national singles title every year from 1920 to 1925. In football, Harold “Red” Grange played for the University of Illinois, averaging over ten yards per carry during his college career. The biggest star of all was the “Sultan of Swat,” Babe Ruth, who became America’s first baseball hero (). He changed the game of baseball from a low-scoring one dominated by pitchers to one where his hitting became famous. By 1923, pitchers frequently chose to intentionally walk him. In 1927, he hit sixty home runs.
### Section Summary
For many middle-class Americans, the 1920s was a decade of unprecedented prosperity. Rising earnings generated more disposable income for the consumption of entertainment, leisure, and consumer goods. This new wealth coincided with and fueled technological innovations, resulting in the booming popularity of entertainments like movies, sports, and radio programs. Henry Ford’s advances in assembly-line efficiency created a truly affordable automobile, making car ownership a possibility for many Americans. Advertising became as big an industry as the manufactured goods that advertisers represented, and many families relied on new forms of credit to increase their consumption levels and strive for a new American standard of living.
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# The Jazz Age: Redefining the Nation, 1919-1929
## Transformation and Backlash
While prosperous, middle-class Americans found much to celebrate about the new era of leisure and consumption, many Americans—often those in rural areas—disagreed on the meaning of a “good life” and how to achieve it. They reacted to the rapid social changes of modern urban society with a vigorous defense of religious values and a fearful rejection of cultural diversity and equality.
### NATIVISM
Beginning at the end of the nineteenth century, immigration into the United States rocketed to never-before-seen heights. Many of these new immigrants were coming from eastern and southern Europe and, for many English-speaking, native-born Americans of northern European descent, the growing diversity of new languages, customs, and religions triggered anxiety and racial animosity. In reaction, some embraced nativism, prizing White Americans with older family trees over more recent immigrants, and rejecting outside influences in favor of their own local customs. Nativists also stoked a sense of fear over the perceived foreign threat, pointing to the anarchist assassinations of the Spanish prime minister in 1897, the Italian king in 1900, and even President William McKinley in 1901 as proof. Following the Bolshevik Revolution in Russia in November 1917, the sense of an inevitable foreign or communist threat only grew among those already predisposed to distrust immigrants.
The sense of fear and anxiety over the rising tide of immigration came to a head with the trial of Nicola Sacco and Bartolomeo Vanzetti (). Sacco and Vanzetti were Italian immigrants who were accused of being part of a robbery and murder in Braintree, Massachusetts, in 1920. There was no direct evidence linking them to the crime, but (in addition to being immigrants) both men were anarchists who favored the destruction of the American market-based, capitalistic society through violence. At their trial, the district attorney emphasized Sacco and Vanzetti’s radical views, and the jury found them guilty on July 14, 1921. Despite subsequent motions and appeals based on ballistics testing, recanted testimony, and an ex-convict’s confession, both men were executed on August 23, 1927.
Opinions on the trial and judgment tended to divide along nativist-immigrant lines, with immigrants supporting the innocence of the condemned pair. The verdict sparked protests from Italian and other immigrant groups, as well as from noted intellectuals such as writer John Dos Passos, satirist Dorothy Parker, and famed physicist Albert Einstein. Muckraker Upton Sinclair based his indictment of the American justice system, the “documentary novel” Boston, on Sacco and Vanzetti’s trial, which he considered a gross miscarriage of justice. As the execution neared, the radical labor union Industrial Workers of the World called for a three-day nationwide walkout, leading to the Great Colorado Coal Strike of 1927. Protests occurred worldwide from Tokyo to Buenos Aires to London ().
One of the most articulate critics of the trial was then-Harvard Law School professor Felix Frankfurter, who would go on to be appointed to the U.S. Supreme Court by Franklin D. Roosevelt in 1939. In 1927, six years after the trial, he wrote in The Atlantic, “By systematic exploitation of the defendants’ alien blood, their imperfect knowledge of English, their unpopular social views, and their opposition to the war, the District Attorney invoked against them a riot of political passion and patriotic sentiment; and the trial judge connived at—one had almost written, cooperated in—the process.”
To “preserve the ideal of American homogeneity,” the Emergency Immigration Act of 1921 introduced numerical limits on European immigration for the first time in U.S. history. These limits were based on a quota system that restricted annual immigration from any given country to 3 percent of the residents from that same country as counted in the 1910 census. The National Origins Act of 1924 went even further, lowering the level to 2 percent of the 1890 census, significantly reducing the share of eligible southern and eastern Europeans, since they had only begun to arrive in the United States in large numbers in the 1890s. Although New York congressmen Fiorello LaGuardia and Emanuel Celler spoke out against the act, there was minimal opposition in Congress, and both labor unions and the Ku Klux Klan supported the bill. When President Coolidge signed it into law, he declared, “America must be kept American.”
### THE KU KLUX KLAN
The concern that a White, Protestant, Anglo-Saxon United States was under siege by throngs of undesirables was not exclusively directed at foreigners. The sense that the country was also facing a threat from within its borders and its own citizenry was also prevalent. This sense was clearly reflected in the popularity of the 1915 motion picture, D. W. Griffith’s The Birth of a Nation (). Based on The Clansman, a 1915 novel by Thomas Dixon, the film offers a racist, White-centric view of the Reconstruction Era. The film depicts noble White southerners made helpless by northern carpetbaggers who empower freed Black people to abuse White men and violate women. The heroes of the film were the Ku Klux Klan, who saved the White people, the South, and the nation. While the film was reviled by many African Americans and the NAACP for its historical inaccuracies and its maligning of freed people, it was celebrated by many White people who accepted the historical revisionism as an accurate portrayal of Reconstruction Era oppression. After viewing the film, President Wilson reportedly remarked, “It is like writing history with lightning, and my only regret is that it is all so terribly true.”
The Ku Klux Klan, which had been dormant since the end of Reconstruction in 1877, experienced a resurgence of attention following the popularity of the film. Just months after the film’s release, a second incarnation of the Klan was established at Stone Mountain, Georgia, under the leadership of William Simmons. This new Klan now publicly eschewed violence and received mainstream support. Its embrace of Protestantism, anti-Catholicism, and anti-Semitism, and its appeals for stricter immigration policies, gained the group a level of acceptance by nativists with similar prejudices. The group was not merely a male organization: The ranks of the Klan also included many women, with chapters of its women’s auxiliary in locations across the country. These women’s groups were active in a number of reform-minded activities, such as advocating for prohibition and the distribution of Bibles at public schools. But they also participated in more expressly Klan activities like burning crosses and the public denunciation of Catholics and Jews (). By 1924, this Second Ku Klux Klan had six million members in the South, West, and, particularly, the Midwest—more Americans than there were in the nation’s labor unions at the time. While the organization publicly abstained from violence, its member continued to employ intimidation, violence, and terrorism against its victims, particularly in the South.
The Klan’s newfound popularity proved to be fairly short-lived. Several states effectively combatted the power and influence of the Klan through anti-masking legislation, that is, laws that barred the wearing of masks publicly. As the organization faced a series of public scandals, such as when the Grand Dragon of Indiana was convicted of murdering a White schoolteacher, prominent citizens became less likely to openly express their support for the group without a shield of anonymity. More importantly, influential people and citizen groups explicitly condemned the Klan. Reinhold Niebuhr, a popular Protestant minister and conservative intellectual in Detroit, admonished the group for its ostensibly Protestant zealotry and anti-Catholicism. Jewish organizations, especially the Anti-Defamation League, which had been founded just a couple of years before the reemergence of the Klan, amplified Jewish discontent at being the focus of Klan attention. And the NAACP, which had actively sought to ban the film The Birth of a Nation, worked to lobby congress and educate the public on lynchings. Ultimately, however, it was the Great Depression that put an end to the Klan. As dues-paying members dwindled, the Klan lost its organizational power and sunk into irrelevance until the 1950s.
### FAITH, FUNDAMENTALISM, AND SCIENCE
The sense of degeneration that the Klan and anxiety over mass immigration prompted in the minds of many Americans was in part a response to the process of postwar urbanization. Cities were swiftly becoming centers of opportunity, but the growth of cities, especially the growth of immigrant populations in those cities, sharpened rural discontent over the perception of rapid cultural change. As more of the population flocked to cities for jobs and quality of life, many left behind in rural areas felt that their way of life was being threatened. To rural Americans, the ways of the city seemed sinful and profligate. Urbanites, for their part, viewed rural Americans as hayseeds who were hopelessly behind the times.
In this urban/rural conflict, Tennessee lawmakers drew a battle line over the issue of evolution and its contradiction of the accepted, biblical explanation of history. Charles Darwin had first published his theory of natural selection in 1859, and by the 1920s, many standard textbooks contained information about Darwin’s theory of evolution. Fundamentalist Protestants targeted evolution as representative of all that was wrong with urban society. Tennessee’s Butler Act made it illegal “to teach any theory that denies the story of the Divine Creation of man as taught in the Bible, and to teach instead that man has descended from a lower order of animals.”
The American Civil Liberties Union (ACLU) hoped to challenge the Butler Act as an infringement of the freedom of speech. As a defendant, the ACLU enlisted teacher and coach John Scopes, who suggested that he may have taught evolution while substituting for an ill biology teacher. Town leaders in Dayton, Tennessee, for their part, sensed an opportunity to promote their town, which had lost more than one-third of its population, and welcomed the ACLU to stage a test case against the Butler Act. The ACLU and the town got their wish as the Scopes Monkey Trial, as the newspapers publicized it, quickly turned into a carnival that captured the attention of the country and epitomized the nation’s urban/rural divide ().
Fundamentalist champion William Jennings Bryan argued the case for the prosecution. Bryan was a three-time presidential candidate and Woodrow Wilson’s Secretary of State until 1915, at which point he began preaching across the country about the spread of secularism and the declining role of religion in education. He was known for offering $100 to anyone who would admit to being descended from an ape. Clarence Darrow, a prominent lawyer and outspoken agnostic, led the defense team. His statement that, “Scopes isn’t on trial, civilization is on trial. No man’s belief will be safe if they win,” struck a chord in society.
The outcome of the trial, in which Scopes was found guilty and fined $100, was never really in question, as Scopes himself had confessed to violating the law. Nevertheless, the trial itself proved to be high drama. The drama only escalated when Darrow made the unusual choice of calling Bryan as an expert witness on the Bible. Knowing of Bryan’s convictions of a literal interpretation of the Bible, Darrow peppered him with a series of questions designed to ridicule such a belief. The result was that those who approved of the teaching of evolution saw Bryan as foolish, whereas many rural Americans considered the cross-examination an attack on the Bible and their faith.
Indicative of the revival of Protestant fundamentalism and the rejection of evolution among rural and White Americans was the rise of Billy Sunday. As a young man, Sunday had gained fame as a baseball player with exceptional skill and speed. Later, he found even more celebrity as the nation’s most revered evangelist, drawing huge crowds at camp meetings around the country. He was one of the most influential evangelists of the time and had access to some of the wealthiest and most powerful families in the country (). Sunday rallied many Americans around “old-time” fundamentalist religion and garnered support for prohibition. Recognizing Sunday’s popular appeal, Bryan attempted to bring him to Dayton for the Scopes trial, although Sunday politely refused.
Even more spectacular than the rise of Billy Sunday was the popularity of Aimee Semple McPherson, a Canadian Pentecostal preacher whose Foursquare Church in Los Angeles catered to the large community of midwestern transplants and newcomers to California (). Although her message promoted the fundamental truths of the Bible, her style was anything but old fashioned. Dressed in tight-fitting clothes and wearing makeup, she held radio-broadcast services in large venues that resembled concert halls and staged spectacular faith-healing performances. Blending Hollywood style and modern technology with a message of fundamentalist Christianity, McPherson exemplified the contradictions of the decade well before public revelations about her scandalous love affair cost her much of her status and following.
### Section Summary
The old and the new came into sharp conflict in the 1920s. In many cases, this divide was geographic as well as philosophical; city dwellers tended to embrace the cultural changes of the era, whereas those who lived in rural towns clung to traditional norms. The Sacco and Vanzetti trial in Massachusetts, as well as the Scopes trial in Tennessee, revealed many Americans’ fears and suspicions about immigrants, radical politics, and the ways in which new scientific theories might challenge traditional Christian beliefs. Some reacted more zealously than others, leading to the inception of nativist and fundamentalist philosophies, and the rise of terror groups such as the Second Ku Klux Klan.
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# The Jazz Age: Redefining the Nation, 1919-1929
## A New Generation
The 1920s was a time of dramatic change in the United States. Many young people, especially those living in big cities, embraced a new morality that was much more permissive than that of previous generations. They listened to jazz music, especially in the nightclubs of Harlem. Although prohibition outlawed alcohol, criminal bootlegging and importing businesses thrived. The decade was not a pleasure cruise for everyone, however; in the wake of the Great War, many were left awaiting the promise of a new generation.
### A NEW MORALITY
Many Americans were disillusioned in the post-World War I era, and their reactions took many forms. Rebellious American youth, in particular, adjusted to the changes by embracing a new morality that was far more permissive than the social mores of their parents. Many young women of the era shed their mother’s morality and adopted the dress and mannerisms of a flapper, the Jazz Age female stereotype, seeking the endless party. Flappers wore shorter skirts, shorter hair, and more makeup, and they drank and smoked with the boys (). Flappers’ dresses emphasized straight lines from the shoulders to the knees, minimizing breasts and curves while highlighting legs and ankles. The male equivalent of a flapper was a “sheik,” although that term has not remained as strong in the American vernacular. At the time, however, many of these fads became a type of conformity, especially among college-aged youths, with the signature bob haircut of the flapper becoming almost universal—in both the United States and overseas.
As men and women pushed social and cultural boundaries in the Jazz Age, sexual mores changed and social customs grew more permissive. “Petting parties” or “necking parties” became the rage on college campuses. Psychologist Sigmund Freud and British “sexologist” Havelock Ellis emphasized that sex was a natural and pleasurable part of the human experience. Margaret Sanger, the founder of Planned Parenthood, launched an information campaign on birth control to give women a choice in the realm in which suffrage had changed little—the family. The popularization of contraception and the private space that the automobile offered to teenagers and unwed couples also contributed to changes in sexual behavior.
Flappers and sheiks also took their cues from the high-flying romances they saw on movie screens and confessions in movie magazines of immorality on movie sets. Movie posters promised: “Brilliant men, beautiful jazz babies, champagne baths, midnight revels, petting parties in the purple dawn, all ending in one terrific smashing climax that makes you gasp.” And “neckers, petters, white kisses, red kisses, pleasure-mad daughters, sensation-craving mothers . . . the truth: bold, naked, sensational.”
New dances and new music—especially jazz—also characterized the Jazz Age. Born out of the African American community, jazz was a uniquely American music. The innovative sound emerged from a number of different communities and from a number of different musical traditions such as blues and ragtime. By the 1920s, jazz had spread from African American clubs in New Orleans and Chicago to reach greater popularity in New York and abroad. One New York jazz establishment, the Cotton Club, became particularly famous and attracted large audiences of hip, young, and White flappers and sheiks to see Black entertainers play jazz ().
### THE “NEW WOMAN”
The Jazz Age and the proliferation of the flapper lifestyle of the 1920s should not be seen merely as the product of postwar disillusionment and newfound prosperity. Rather, the search for new styles of dress and new forms of entertainment like jazz was part of a larger women’s rights movement. The early 1920s, especially with the ratification of the Nineteenth Amendment guaranteeing full voting rights to women, was a period that witnessed the expansion of women’s political power. The public flaunting of social and sexual norms by flappers represented an attempt to match gains in political equality with gains in the social sphere. Women were increasingly leaving the Victorian era norms of the previous generation behind, as they broadened the concept of women’s liberation to include new forms of social expression such as dance, fashion, women’s clubs, and forays into college and the professions.
Nor did the struggle for women’s rights through the promotion and passage of legislation cease in the 1920s. In 1921, Congress passed the Promotion of the Welfare and Hygiene of Maternity and Infancy Act, also known as the Sheppard-Towner Act, which earmarked $1.25 million for well-baby clinics and educational programs, as well as nursing. This funding dramatically reduced the rate of infant mortality. Two years later, in 1923, Alice Paul drafted and promoted an Equal Rights Amendment (ERA) that promised to end all sex discrimination by guaranteeing that “Men and women shall have equal rights throughout the United States and every place subject to its jurisdiction.”
Yet, ironically, at precisely the time when the Progressive movement was achieving its long-sought-after goals, the movement itself was losing steam and the Progressive Era was coming to a close. As the heat of Progressive politics grew less intense, voter participation from both sexes declined over the course of the 1920s. After the passage of the Nineteenth Amendment, many women believed that they had accomplished their goals and dropped out of the movement. As a result, the proposed ERA stalled (the ERA eventually passed Congress almost fifty years later in 1972, but then failed to win ratification by a sufficient number of states), and, by the end of the 1920s, Congress even allowed funding for the Sheppard-Towner Act to lapse.
The growing lethargy toward women’s rights was happening at a time when an increasing number of women were working for wages in the U.S. economy—not only in domestic service, but in retail, healthcare and education, offices, and manufacturing. Beginning in the 1920s, women’s participation in the labor force increased steadily. However, most were paid less than men for the same type of work based on the rationale that they did not have to support a family. While the employment of single and unmarried women had largely won social acceptance, married women often suffered the stigma that they were working for pin money—frivolous additional discretionary income.
### THE HARLEM RENAISSANCE AND THE NEW NEGRO
It wasn’t only women who found new forms of expression in the 1920s. African Americans were also expanding their horizons and embracing the concept of the “new Negro.” The decade witnessed the continued Great Migration of African Americans to the North, with over half a million fleeing the strict Jim Crow laws of the South. Life in the northern states, as many African Americans discovered, was hardly free of discrimination and segregation. Even without Jim Crow, businesses, property owners, employers, and private citizens typically practiced de facto segregation, which could be quite stifling and oppressive. Nonetheless, many southern Black people continued to move north into segregated neighborhoods that were already bursting at the seams, because the North, at the very least, offered two tickets toward Black progress: schools and the vote. The Black population of New York City doubled during the decade. As a result, Harlem, a neighborhood at the northern end of Manhattan, became a center for Afro-centric art, music, poetry, and politics. Political expression in the Harlem of the 1920s ran the gamut, as some leaders advocated a return to Africa, while others fought for inclusion and integration.
Revived by the wartime migration and fired up by the violence of the postwar riots, urban Black people developed a strong cultural expression in the 1920s that came to be known as the Harlem Renaissance. In this rediscovery of Black culture, African American artists and writers formulated an independent Black culture and encouraged racial pride, rejecting any emulation of American culture. Claude McKay’s poem “If We Must Die” called on African Americans to start fighting back in the wake of the Red Summer riots of 1919 (discussed in a previous chapter, ). Langston Hughes, often nicknamed the “poet laureate” of the movement, invoked sacrifice and the just cause of civil rights in “The Colored Soldier,” while another author of the movement, Zora Neale Hurston, celebrated the life and dialect of rural Black people in a fictional, all-Black town in Florida. Hurston’s Their Eyes Were Watching God was published in 1937.
The new Negro found political expression in a political ideology that celebrated African Americans distinct national identity. This Negro nationalism, as some referred to it, proposed that African Americans had a distinct and separate national heritage that should inspire pride and a sense of community. An early proponent of such nationalism was W. E. B. Du Bois. One of the founders of the NAACP, a brilliant writer and scholar, and the first African American to earn a Ph.D. from Harvard, Du Bois openly rejected assumptions of White supremacy. His conception of Negro nationalism encouraged Africans to work together in support of their own interests, promoted the elevation of Black literature and cultural expression, and, most famously, embraced the African continent as the true homeland of all ethnic Africans—a concept known as Pan-Africanism.
Taking Negro nationalism to a new level was Marcus Garvey. Like many Black Americans, the Jamaican immigrant had become utterly disillusioned with the prospect of overcoming racism in the United States in the wake of the postwar riots and promoted a “Back to Africa” movement. To return African Americans to a presumably more welcoming home in Africa, Garvey founded the Black Star Steamship Line. He also started the United Negro Improvement Association (UNIA), which attracted thousands of primarily lower-income working people. UNIA members wore colorful uniforms and promoted the doctrine of a “negritude” that reversed the color hierarchy of White supremacy, prizing Blackness and identifying light skin as a mark of inferiority. Intellectual leaders like Du Bois, whose lighter skin put him low on Garvey’s social order, considered the UNIA leader a charlatan. Garvey was eventually imprisoned for mail fraud and then deported, but his legacy set the stage for Malcolm X and the Black Power movement of the 1960s.
### PROHIBITION
At precisely the same time that African Americans and women were experimenting with new forms of social expression, the country as a whole was undergoing a process of austere and dramatic social reform in the form of alcohol prohibition. After decades of organizing to reduce or end the consumption of alcohol in the United States, temperance groups and the Anti-Saloon League finally succeeded in pushing through the Eighteenth Amendment in 1919, which banned the manufacture, sale, and transportation of intoxicating liquors (). The law proved difficult to enforce, as illegal alcohol soon poured in from Canada and the Caribbean, and rural Americans resorted to home-brewed “moonshine.” The result was an eroding of respect for law and order, as many people continued to drink illegal liquor. Rather than bringing about an age of sobriety, as Progressive reformers had hoped, it gave rise to a new subculture that included illegal importers, interstate smuggling (or bootlegging), clandestine saloons referred to as “speakeasies,” hipflasks, cocktail parties, and the organized crime of trafficking liquor.
Prohibition also revealed deep political divisions in the nation. The Democratic Party found itself deeply divided between urban, northern “wets” who hated the idea of abstinence, and rural, southern “dries” who favored the amendment. This divided the party and opened the door for the Republican Party to gain ascendancy in the 1920s. All politicians, including Woodrow Wilson, Herbert Hoover, Robert La Follette, and Franklin D. Roosevelt, equivocated in their support for the law. Publicly, they catered to the Anti-Saloon League; however, they failed to provide funding for enforcement.
Prohibition sparked a rise in organized crime. “Scarface” Al Capone () ran an extensive bootlegging and criminal operation known as the Chicago Outfit or Chicago mafia. By 1927, Capone’s organization included a number of illegal activities including bootlegging, prostitution, gambling, loan sharking, and even murder. His operation was earning him more than $100 million annually, and many local police were on his payroll. Although he did not have a monopoly on crime, his organizational structure was better than many other criminals of his era. His liquor trafficking business and his Chicago soup kitchens during the Great Depression led some Americans to liken Capone to a modern-day Robin Hood. Still, Capone was eventually imprisoned for eleven years for tax evasion, including a stint in California’s notorious Alcatraz prison.
### THE LOST GENERATION
As the country struggled with the effects and side-effects of prohibition, many young intellectuals endeavored to come to grips with a lingering sense of disillusionment. World War I, fundamentalism, and the Red Scare—a pervasive American fear of Communist infiltrators prompted by the success of the Bolshevik Revolution—all left their mark on these intellectuals. Known as the Lost Generation, writers like F. Scott Fitzgerald, Ernest Hemingway, Sinclair Lewis, Edith Wharton, and John Dos Passos expressed their hopelessness and despair by skewering the middle class in their work. They felt alienated from society, so they tried to escape (some literally) to criticize it. Many lived an expatriate life in Paris for the decade, although others went to Rome or Berlin.
The Lost Generation writer that best exemplifies the mood of the 1920s was F. Scott Fitzgerald, now considered one of the most influential writers of the twentieth century. His debut novel, This Side of Paradise, describes a generation of youth “grown up to find all gods dead, all wars fought, all faith in man shaken.” The Great Gatsby, published in 1925, exposed the doom that always follows the fun, fast-lived life. Fitzgerald depicted the modern millionaire Jay Gatsby living a profligate life: unscrupulous, coarse, and in love with another man’s wife. Both Fitzgerald and his wife Zelda lived this life as well, squandering the money he made from his writing.
Equally idiosyncratic and disillusioned was writer Ernest Hemingway (). He lived a peripatetic and adventurous lifestyle in Europe, Cuba, and Africa, working as an ambulance driver in Italy during World War I and traveling to Spain in the 1930s to cover the civil war there. His experiences of war and tragedy stuck with him, emerging in colorful scenes in his novels The Sun Also Rises (1926), A Farewell to Arms (1929), and For Whom the Bell Tolls (1940). In 1952, his novella, The Old Man and the Sea, won the Pulitzer Prize. Two years later, he won the Nobel Prize in Literature for this book and his overall influence on contemporary style.
Not all Lost Generation writers were like Fitzgerald or Hemingway. The writing of Sinclair Lewis, rather than expressing a defined disillusionment, was more influenced by the Progressivism of the previous generation. In Babbitt (1922), he examined the “sheep following the herd” mentality that conformity promoted. He satirized American middle-class life as pleasure seeking and mindless. Similarly, writer Edith Wharton celebrated life in old New York, a vanished society, in The Age of Innocence, in 1920. Wharton came from a very wealthy, socialite family in New York, where she was educated by tutors and never attended college. She lived for many years in Europe; during the Great War, she worked in Paris helping women establish businesses.
### Section Summary
Different groups reacted to the upheavals of the 1920s in different ways. Some people, especially young urbanites, embraced the new amusements and social venues of the decade. Women found new opportunities for professional and political advancement, as well as new models of sexual liberation; however, the women’s rights movement began to wane with the passage of the Nineteenth Amendment. For Black artists of the Harlem Renaissance, the decade was marked less by leisure and consumption than by creativity and purpose. African American leaders like Marcus Garvey and W. E. B. Du Bois responded to the retrenched racism of the time with different campaigns for civil rights and Black empowerment. Others, like the writers of the Lost Generation, reveled in exposing the hypocrisies and shallowness of mainstream middle-class culture. Meanwhile, the passage of prohibition served to increase the illegal production of alcohol and led to a rise in organized crime.
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# The Jazz Age: Redefining the Nation, 1919-1929
## Republican Ascendancy: Politics in the 1920s
The election of 1920 saw the weakening of the Democratic Party. The death of Theodore Roosevelt and Woodrow Wilson’s ill health meant the passing of a generation of Progressive leaders. The waning of the Red Scare took with it the last vestiges of Progressive zeal, and Wilson’s support of the League of Nations turned Irish and German immigrants against the Democrats. Americans were tired of reform, tired of witch hunts, and were more than ready for a return to “normalcy.”
Above all, the 1920s signaled a return to a pro-business government—almost a return to the laissez-faire politics of the Gilded Age of the late nineteenth century. Calvin Coolidge’s statement that “the chief business of the American people is business,” often rendered as “the business of America is business” became the dominant attitude.
### WARREN HARDING AND THE RETURN TO NORMALCY
In the election of 1920, professional Republicans were eager to nominate a man whom they could manage and control. Warren G. Harding, a senator from Ohio, represented just such a man (). Before his nomination, Harding stated, “America’s present need is not heroics but healing; not nostrums but normalcy; not revolution but restoration.” Harding was genial and affable, but not everyone appreciated his speeches; Democratic presidential-hopeful William Gibbs McAdoo described Harding’s speeches as “an army of pompous phrases moving across the landscape in search of an idea.” H. L. Mencken, the great social critic of the 1920s, wrote of Harding’s speaking, “It drags itself out of the dark abysm of pish, and crawls insanely up to the top-most pinnacle of posh. It is rumble and bumble. It is flap and doodle. It is balder and dash.”
Harding was known for enjoying golf, alcohol, and poker (not necessarily in that order). Although his critics depicted him as weak, lazy, or incompetent, he was actually quite shrewd and politically astute. Together with his running mate, Calvin Coolidge, the governor of Massachusetts, they attracted the votes of many Americans who sought Harding’s promised return to normalcy. In the election, Harding defeated Governor James Cox of Ohio by the greatest majority in the history of two-party politics: 61 percent of the popular vote.
Harding’s cabinet reflected his pro-business agenda. Herbert Hoover, a millionaire mechanical engineer and miner, became his Secretary of Commerce. Hoover had served as head of the relief effort for Belgium during World War I and helped to feed those in Russia and Germany after the war ended. He was a very effective administrator, seeking to limit inefficiency in the government and promoting partnerships between government and businesses. Harding’s Secretary of the Treasury, Andrew Mellon, was also a pro-business multimillionaire with a fortune built in banking and aluminum. Even more so than Hoover, Mellon entered public service with a strong sense that government should run as efficiently as any business, famously writing that “the Government is just a business, and can and should be run on business principles.”
Consistent with his principles of running government with business-like efficiency, Harding proposed and signed into law tax rate cuts as well as the country’s first formal budgeting process, which created a presidential budget director and required that the president submit an annual budget to Congress. These policies helped to reduce the debt that the United States had incurred during World War I. However, as Europe began to recover, U.S. exports to the continent dwindled. In an effort to protect U.S. agriculture and other businesses threatened by lower-priced imports, Harding pushed through the Emergency Tariff of 1921. This defensive tariff had the effect of increasing American purchasing power, although it also inflated the prices of many goods.
In the area of foreign policy, Harding worked to preserve the peace through international cooperation and the reduction of armaments around the world. Despite the refusal of the U.S. Senate to ratify the Treaty of Versailles, Harding was able to work with Germany and Austria to secure a formal peace. He convened a conference in Washington that brought world leaders together to agree on reducing the threat of future wars by reducing armaments. Out of these negotiations came a number of treaties designed to foster cooperation in the Far East, reduce the size of navies around the world, and establish guidelines for submarine usage. These agreements ultimately fell apart in the 1930s, as the world descended into war again. But, at the time, they were seen as a promising path to maintaining the peace.
Despite these developments, the Harding administration has gone down in history as one that was especially ridden with scandal. While Harding was personally honest, he surrounded himself with politicians who weren’t. Harding made the mistake of often turning to unscrupulous advisors or even his “Ohio Gang” of drinking and poker buddies for advice and guidance. And, as he himself recognized, this group tended to cause him grief. “I have no trouble with my enemies,” he once commented. “I can take care of my enemies in a fight. But my friends, my goddamned friends, they’re the ones who keep me walking the floor at nights!”
The scandals mounted quickly. From 1920 to 1923, Secretary of the Interior Albert B. Fall was involved in a scam that became known as the Teapot Dome scandal. Fall had leased navy reserves in Teapot Dome, Wyoming, and two other sites in California to private oil companies without opening the bidding to other companies. In exchange, the companies gave him $300,000 in cash and bonds, as well as a herd of cattle for his ranch. Fall was convicted of accepting bribes from the oil companies; he was fined $100,000 and sentenced to a year in prison. It was the first time that a cabinet official had received such a sentence.
In 1923, Harding also learned that the head of the Veterans’ Bureau, Colonel Charles Forbes, had absconded with most of the $250 million set aside for extravagant bureau functions. Harding allowed Forbes to resign and leave the country; however, after the president died, Forbes returned and was tried, convicted, and sentenced to two years in Leavenworth prison.
Although the Harding presidency had a number of large successes and variety of dark scandals, it ended before the first term was up. In July 1923, while traveling in Seattle, the president suffered a heart attack. On August 2, in his weakened condition, he suffered a stroke and died in San Francisco, leaving the presidency to his vice president, Calvin Coolidge. As for Harding, few presidents were so deeply mourned by the populace. His kindly nature and ability to poke fun at himself endeared him to the public.
### A MAN OF FEW WORDS
Coolidge ended the scandals, but did little beyond that. Walter Lippman wrote in 1926 that “Mr. Coolidge’s genius for inactivity is developed to a very high point. It is a grim, determined, alert inactivity, which keeps Mr. Coolidge occupied constantly.”
Coolidge had a strong belief in the Puritan work ethic: Work hard, save your money, keep your mouth shut and listen, and good things will happen to you. Known as “Silent Cal,” his clean image seemed capable of cleaning up scandals left by Harding. Republicans—and the nation—now had a president who combined a preference for normalcy with the respectability and honesty that was absent from the Harding administration.
Coolidge’s first term was devoted to eliminating the taint of scandal that Harding had brought to the White House. Domestically, Coolidge adhered to the creed: “The business of America is business.” He stood in awe of Andrew Mellon and followed his fiscal policies, which made him the only president to turn a legitimate profit in the White House. Coolidge believed the rich were worthy of their property and that poverty was the wage of sin. Most importantly, Coolidge believed that since only the rich best understood their own interests, the government should let businessmen handle their own affairs with as little federal intervention as possible. Coolidge was quoted as saying, “The man who builds a factory builds a temple. The man who works there worships there.”
Thus, silence and inactivity became the dominant characteristics of the Coolidge presidency. Coolidge’s legendary reserve was famous in Washington society. Contemporaries told a possibly apocryphal story of how, at a dinner party at the White House, a woman bet her friends that she could get Coolidge to say more than three words. He looked at her and said, “you lose.”
The 1924 election saw Coolidge win easily over the divided Democrats, who fought over their nomination. Southerners wanted to nominate pro-prohibition, pro-Klan, anti-immigrant candidate William G. McAdoo. The eastern establishment wanted Alfred E. Smith, a Catholic, urban, and anti-prohibition candidate. After many battles, they compromised on corporation lawyer John W. Davis. Midwesterner Robert M. La Follette, promoted by farmers, socialists, and labor unions, attempted to resurrect the Progressive Party. Coolidge easily beat both candidates.
### THE ELECTION OF 1928
This cultural battle between the forces of reaction and rebellion appeared to culminate with the election of 1928, the height of Republican ascendancy. On August 2, 1927, Coolidge announced that he would not be participating in the 1928 election; “I choose not to run,” was his comment (). Republicans promoted the heir apparent, Secretary of Commerce Herbert Hoover. The Democrats nominated Governor Alfred E. Smith of New York. Smith represented everything that small-town, rural America hated: He was Irish, Catholic, anti-prohibition, and a big-city politician. He was very flamboyant and outspoken, which also did not go over well with many Americans.
Republican prosperity carried the day once again, and Hoover won easily with twenty-one million votes over Al Smith’s fifteen million. The stock market continued to rise, and prosperity was the watchword of the day. Many Americans who had not done so before invested in the market, believing that the prosperous times would continue.
As Hoover came into office, Americans had every reason to believe that prosperity would continue forever. In less than a year, however, the bubble would burst, and a harsh reality would take its place.
### Section Summary
After World War I, Americans were ready for “a return to normalcy,” and Republican Warren Harding offered them just that. Under the guidance of his big-business backers, Harding’s policies supported businesses at home and isolation from foreign affairs. His administration was wracked by scandals, and after he died in 1923, Calvin Coolidge continued his policy legacy in much the same vein. Herbert Hoover, elected as Coolidge’s heir apparent, planned for more of the same until the stock market crash ended a decade of Republican ascendancy.
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### Critical Thinking Questions
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# Brother, Can You Spare a Dime? The Great Depression, 1929-1932
## Introduction
On March 4, 1929, at his presidential inauguration, Herbert Hoover stated, “I have no fears for the future of our country. It is bright with hope.” Most Americans shared his optimism. They believed that the prosperity of the 1920s would continue, and that the country was moving closer to a land of abundance for all. Little could Hoover imagine that barely a year into his presidency, shantytowns known as “Hoovervilles” would emerge on the fringes of most major cities (), newspapers covering the homeless would be called “Hoover blankets,” and pants pockets, turned inside-out to show their emptiness, would become “Hoover flags.”
The stock market crash of October 1929 set the Great Depression into motion, but other factors were at the root of the problem, propelled onward by a series of both human-made and natural catastrophes. Anticipating a short downturn and living under an ethos of free enterprise and individualism, Americans suffered mightily in the first years of the Depression. As conditions worsened and the government failed to act, they grew increasingly desperate for change. While Hoover could not be blamed for the Great Depression, his failure to address the nation’s hardships would remain his legacy. |
# Brother, Can You Spare a Dime? The Great Depression, 1929-1932
## The Stock Market Crash of 1929
Herbert Hoover became president at a time of ongoing prosperity in the country. Americans hoped he would continue to lead the country through still more economic growth, and neither he nor the country was ready for the unraveling that followed. But Hoover’s moderate policies, based upon a strongly held belief in the spirit of American individualism, were not enough to stem the ever-growing problems, and the economy slipped further and further into the Great Depression.
While it is misleading to view the stock market crash of 1929 as the sole cause of the Great Depression, the dramatic events of that October did play a role in the downward spiral of the American economy. The crash, which took place less than a year after Hoover was inaugurated, was the most extreme sign of the economy’s weakness. Multiple factors contributed to the crash, which in turn caused a consumer panic that drove the economy even further downhill, in ways that neither Hoover nor the financial industry was able to restrain. Hoover, like many others at the time, thought and hoped that the country would right itself with limited government intervention. This was not the case, however, and millions of Americans sank into grinding poverty.
### THE EARLY DAYS OF HOOVER’S PRESIDENCY
Upon his inauguration, President Hoover set forth an agenda that he hoped would continue the “Coolidge prosperity” of the previous administration. While accepting the Republican Party’s presidential nomination in 1928, Hoover commented, “Given the chance to go forward with the policies of the last eight years, we shall soon with the help of God be in sight of the day when poverty will be banished from this nation forever.” In the spirit of normalcy that defined the Republican ascendancy of the 1920s, Hoover planned to immediately overhaul federal regulations with the intention of allowing the nation’s economy to grow unfettered by any controls. The role of the government, he contended, should be to create a partnership with the American people, in which the latter would rise (or fall) on their own merits and abilities. He felt the less government intervention in their lives, the better.
Yet, to listen to Hoover’s later reflections on Franklin Roosevelt’s first term in office, one could easily mistake his vision for America for the one held by his successor. Speaking in 1936 before an audience in Denver, Colorado, he acknowledged that it was always his intent as president to ensure “a nation built of home owners and farm owners. We want to see more and more of them insured against death and accident, unemployment and old age,” he declared. “We want them all secure.” Herbert Hoover, address delivered in Denver, Colorado, 30 October 1936, compiled in Hoover, Such humanitarianism was not uncommon to Hoover. Throughout his early career in public service, he was committed to relief for people around the world. In 1900, he coordinated relief efforts for foreign nationals trapped in China during the Boxer Rebellion. At the outset of World War I, he led the food relief effort in Europe, specifically helping millions of Belgians who faced German forces. President Woodrow Wilson subsequently appointed him head of the U.S. Food Administration to coordinate rationing efforts in America as well as to secure essential food items for the Allied forces and citizens in Europe.
Hoover’s first months in office hinted at the reformist, humanitarian spirit that he had displayed throughout his career. He continued the civil service reform of the early twentieth century by expanding opportunities for employment throughout the federal government. In response to the Teapot Dome Affair, which had occurred during the Harding administration, he invalidated several private oil leases on public lands. He directed the Department of Justice, through its Bureau of Investigation, to crack down on organized crime, resulting in the arrest and imprisonment of Al Capone. By the summer of 1929, he had signed into law the creation of a Federal Farm Board to help farmers with government price supports, expanded tax cuts across all income classes, and set aside federal funds to clean up slums in major American cities. To directly assist several overlooked populations, he created the Veterans Administration and expanded veterans’ hospitals, established the Federal Bureau of Prisons to oversee incarceration conditions nationwide, and reorganized the Bureau of Indian Affairs to further protect Native Americans. Just prior to the stock market crash, he even proposed the creation of an old-age pension program, promising fifty dollars monthly to all Americans over the age of sixty-five—a proposal remarkably similar to the social security benefit that would become a hallmark of Roosevelt’s subsequent New Deal programs. As the summer of 1929 came to a close, Hoover remained a popular successor to Calvin “Silent Cal” Coolidge, and all signs pointed to a highly successful administration.
### THE GREAT CRASH
The promise of the Hoover administration was cut short when the stock market lost almost one-half its value in the fall of 1929, plunging many Americans into financial ruin. However, as a singular event, the stock market crash itself did not cause the Great Depression that followed. In fact, only approximately 10 percent of American households held stock investments and speculated in the market; yet nearly a third would lose their lifelong savings and jobs in the ensuing depression. The connection between the crash and the subsequent decade of hardship was complex, involving underlying weaknesses in the economy that many policymakers had long ignored.
### What Was the Crash?
To understand the crash, it is useful to address the decade that preceded it. The prosperous 1920s ushered in a feeling of euphoria among middle-class and wealthy Americans, and people began to speculate on wilder investments. The government was a willing partner in this endeavor: The Federal Reserve followed a brief postwar recession in 1920–1921 with a policy of setting interest rates artificially low, as well as easing the reserve requirements on the nation’s largest banks. As a result, the money supply in the U.S. increased by nearly 60 percent, which convinced even more Americans of the safety of investing in questionable schemes. They felt that prosperity was boundless and that extreme risks were likely tickets to wealth. Named for Charles Ponzi, the original “Ponzi schemes” emerged early in the 1920s to encourage novice investors to divert funds to unfounded ventures, which in reality simply used new investors’ funds to pay off older investors as the schemes grew in size. Speculation, where investors purchased into high-risk schemes that they hoped would pay off quickly, became the norm. Several banks, including deposit institutions that originally avoided investment loans, began to offer easy credit, allowing people to invest, even when they lacked the money to do so. An example of this mindset was the Florida land boom of the 1920s: Real estate developers touted Florida as a tropical paradise and investors went all in, buying land they had never seen with money they didn’t have and selling it for even higher prices.
The Florida land boom went bust in 1925–1926. A combination of negative press about the speculative nature of the boom, IRS investigations into the questionable financial practices of several land brokers, and a railroad embargo that limited the delivery of construction supplies into the region significantly hampered investor interest. The subsequent Great Miami Hurricane of 1926 drove most land developers into outright bankruptcy. However, speculation continued throughout the decade, this time in the stock market. Buyers purchased stock “on margin”—buying for a small down payment with borrowed money, with the intention of quickly selling at a much higher price before the remaining payment came due—which worked well as long as prices continued to rise. Speculators were aided by retail stock brokerage firms, which catered to average investors anxious to play the market but lacking direct ties to investment banking houses or larger brokerage firms. When prices began to fluctuate in the summer of 1929, investors sought excuses to continue their speculation. When fluctuations turned to outright and steady losses, everyone started to sell. As September began to unfold, the Dow Jones Industrial Average peaked at a value of 381 points, or roughly ten times the stock market’s value, at the start of the 1920s.
Several warning signs portended the impending crash but went unheeded by Americans still giddy over the potential fortunes that speculation might promise. A brief downturn in the market on September 18, 1929, raised questions among more-seasoned investment bankers, leading some to predict an end to high stock values, but did little to stem the tide of investment. Even the collapse of the London Stock Exchange on September 20 failed to fully curtail the optimism of American investors. However, when the New York Stock Exchange lost 11 percent of its value on October 24—often referred to as “Black Thursday”—key American investors sat up and took notice. In an effort to forestall a much-feared panic, leading banks, including Chase National, National City, J.P. Morgan, and others, conspired to purchase large amounts of blue chip stocks (including U.S. Steel) in order to keep the prices artificially high. Even that effort failed in the growing wave of stock sales. Nevertheless, Hoover delivered a radio address on Friday in which he assured the American people, “The fundamental business of the country . . . is on a sound and prosperous basis.”
As newspapers across the country began to cover the story in earnest, investors anxiously awaited the start of the following week. When the Dow Jones Industrial Average lost another 13 percent of its value on Monday morning, many knew the end of stock market speculation was near. The evening before the infamous crash was ominous. Jonathan Leonard, a newspaper reporter who regularly covered the stock market beat, wrote of how Wall Street “lit up like a Christmas tree.” Brokers and businessmen who feared the worst the next day crowded into restaurants and speakeasies (a place where alcoholic beverages were illegally sold). After a night of heavy drinking, they retreated to nearby hotels or flop-houses (cheap boarding houses), all of which were overbooked, and awaited sunrise. Children from nearby slums and tenement districts played stickball in the streets of the financial district, using wads of ticker tape for balls. Although they all awoke to newspapers filled with predictions of a financial turnaround, as well as technical reasons why the decline might be short-lived, the crash on Tuesday morning, October 29, caught few by surprise.
No one even heard the opening bell on Wall Street that day, as shouts of “Sell! Sell!” drowned it out. In the first three minutes alone, nearly three million shares of stock, accounting for $2 million of wealth, changed hands. The volume of Western Union telegrams tripled, and telephone lines could not meet the demand, as investors sought any means available to dump their stock immediately. Rumors spread of investors jumping from their office windows. Fistfights broke out on the trading floor, where one broker fainted from physical exhaustion. Stock trades happened at such a furious pace that runners had nowhere to store the trade slips, and so they resorted to stuffing them into trash cans. Although the stock exchange’s board of governors briefly considered closing the exchange early, they subsequently chose to let the market run its course, lest the American public panic even further at the thought of closure. When the final bell rang, errand boys spent hours sweeping up tons of paper, tickertape, and sales slips. Among the more curious finds in the rubbish were torn suit coats, crumpled eyeglasses, and one broker’s artificial leg. Outside a nearby brokerage house, a policeman allegedly found a discarded birdcage with a live parrot squawking, “More margin! More margin!”
On Black Tuesday, October 29, stock holders traded over sixteen million shares and lost over $14 billion in wealth in a single day. To put this in context, a trading day of three million shares was considered a busy day on the stock market. People unloaded their stock as quickly as they could, never minding the loss. Banks, facing debt and seeking to protect their own assets, demanded payment for the loans they had provided to individual investors. Those individuals who could not afford to pay found their stocks sold immediately and their life savings wiped out in minutes, yet their debt to the bank still remained ().
The financial outcome of the crash was devastating. Between September 1 and November 30, 1929, the stock market lost over one-half its value, dropping from $64 billion to approximately $30 billion. Any effort to stem the tide was, as one historian noted, tantamount to bailing Niagara Falls with a bucket. The crash affected many more than the relatively few Americans who invested in the stock market. While only 10 percent of households had investments, over 90 percent of all banks had invested in the stock market. Many banks failed due to their dwindling cash reserves. This was in part due to the Federal Reserve lowering the limits of cash reserves that banks were traditionally required to hold in their vaults, as well as the fact that many banks invested in the stock market themselves. Eventually, thousands of banks closed their doors after losing all of their assets, leaving their customers penniless. While a few savvy investors got out at the right time and eventually made fortunes buying up discarded stock, those success stories were rare. Housewives who speculated with grocery money, bookkeepers who embezzled company funds hoping to strike it rich and pay the funds back before getting caught, and bankers who used customer deposits to follow speculative trends all lost. While the stock market crash was the trigger, the lack of appropriate economic and banking safeguards, along with a public psyche that pursued wealth and prosperity at all costs, allowed this event to spiral downward into a depression.
### Causes of the Crash
The crash of 1929 did not occur in a vacuum, nor did it cause the Great Depression. Rather, it was a tipping point where the underlying weaknesses in the economy, specifically in the nation’s banking system, came to the fore. It also represented both the end of an era characterized by blind faith in American exceptionalism and the beginning of one in which citizens began increasingly to question some long-held American values. A number of factors played a role in bringing the stock market to this point and contributed to the downward trend in the market, which continued well into the 1930s. In addition to the Federal Reserve’s questionable policies and misguided banking practices, three primary reasons for the collapse of the stock market were international economic woes, poor income distribution, and the psychology of public confidence.
After World War I, both America’s allies and the defeated nations of Germany and Austria contended with disastrous economies. The Allies owed large amounts of money to U.S. banks, which had advanced them money during the war effort. Unable to repay these debts, the Allies looked to reparations from Germany and Austria to help. The economies of those countries, however, were struggling badly, and they could not pay their reparations, despite the loans that the U.S. provided to assist with their payments. The U.S. government refused to forgive these loans, and American banks were in the position of extending additional private loans to foreign governments, who used them to repay their debts to the U.S. government, essentially shifting their obligations to private banks. When other countries began to default on this second wave of private bank loans, still more strain was placed on U.S. banks, which soon sought to liquidate these loans at the first sign of a stock market crisis.
Poor income distribution among Americans compounded the problem. A strong stock market relies on today’s buyers becoming tomorrow’s sellers, and therefore it must always have an influx of new buyers. In the 1920s, this was not the case. Eighty percent of American families had virtually no savings, and only one-half to 1 percent of Americans controlled over a third of the wealth. This scenario meant that there were no new buyers coming into the marketplace, and nowhere for sellers to unload their stock as the speculation came to a close. In addition, the vast majority of Americans with limited savings lost their accounts as local banks closed, and likewise lost their jobs as investment in business and industry came to a screeching halt.
Finally, one of the most important factors in the crash was the contagion effect of panic. For much of the 1920s, the public felt confident that prosperity would continue forever, and therefore, in a self-fulfilling cycle, the market continued to grow. But once the panic began, it spread quickly and with the same cyclical results; people were worried that the market was going down, they sold their stock, and the market continued to drop. This was partly due to Americans’ inability to weather market volatility, given the limited cash surpluses they had on hand, as well as their psychological concern that economic recovery might never happen.
### IN THE AFTERMATH OF THE CRASH
After the crash, Hoover announced that the economy was “fundamentally sound.” On the last day of trading in 1929, the New York Stock Exchange held its annual wild and lavish party, complete with confetti, musicians, and illegal alcohol. The U.S. Department of Labor predicted that 1930 would be “a splendid employment year.” These sentiments were not as baseless as it may seem in hindsight. Historically, markets cycled up and down, and periods of growth were often followed by downturns that corrected themselves. But this time, there was no market correction; rather, the abrupt shock of the crash was followed by an even more devastating depression. Investors, along with the general public, withdrew their money from banks by the thousands, fearing the banks would go under. The more people pulled out their money in bank runs, the closer the banks came to insolvency ().
The contagion effect of the crash grew quickly. With investors losing billions of dollars, they invested very little in new or expanded businesses. At this time, two industries had the greatest impact on the country’s economic future in terms of investment, potential growth, and employment: automotive and construction. After the crash, both were hit hard. In November 1929, fewer cars were built than in any other month since November 1919. Even before the crash, widespread saturation of the market meant that few Americans bought them, leading to a slowdown. Afterward, very few could afford luxury cars, like Stutz, Deusenberg, and Pierce-Arrow, so these car companies gradually went out of business in the 1930s. In construction, the drop-off was even more dramatic. It would be another thirty years before a new hotel or theater was built in New York City. The Empire State Building itself stood half empty for years after being completed in 1931.
The damage to major industries led to, and reflected, limited purchasing by both consumers and businesses. Even those Americans who continued to make a modest income during the Great Depression lost the drive for conspicuous consumption that they exhibited in the 1920s. People with less money to buy goods could not help businesses grow; in turn, businesses with no market for their products could not hire workers or purchase raw materials. Employers began to lay off workers. The country’s gross national product declined by over 25 percent within a year, and wages and salaries declined by $4 billion. Unemployment tripled, from 1.5 million at the end of 1929 to 4.5 million by the end of 1930. By mid-1930, the slide into economic chaos had begun but was nowhere near complete.
### THE NEW REALITY FOR AMERICANS
For most Americans, the crash affected daily life in myriad ways. In the immediate aftermath, there was a run on the banks, where citizens took their money out, if they could get it, and hid their savings under mattresses, in bookshelves, or anywhere else they felt was safe. Some went so far as to exchange their dollars for gold and ship it out of the country. A number of banks failed outright, and others, in their attempts to stay solvent, called in loans that people could not afford to repay. Working-class Americans saw their wages drop: Even Henry Ford, the champion of a high minimum wage, began lowering wages by as much as a dollar a day. Southern cotton planters paid workers only twenty cents for every one hundred pounds of cotton picked, meaning that the strongest picker might earn sixty cents for a fourteen-hour day of work. Cities struggled to collect property taxes and subsequently laid off teachers and police.
The new hardships that people faced were not always immediately apparent; many communities felt the changes but could not necessarily look out their windows and see anything different. Men who lost their jobs didn’t stand on street corners begging; they disappeared. They might be found keeping warm by a trashcan bonfire or picking through garbage at dawn, but mostly, they stayed out of public view. As the effects of the crash continued, however, the results became more evident. Those living in cities grew accustomed to seeing long breadlines of unemployed men waiting for a meal (). Companies fired workers and tore down employee housing to avoid paying property taxes. The landscape of the country had changed.
The hardships of the Great Depression threw family life into disarray. Both marriage and birth rates declined in the decade after the crash. The most vulnerable members of society—children, women, minorities, and the working class—struggled the most. Parents often sent children out to beg for food at restaurants and stores to save themselves from the disgrace of begging. Many children dropped out of school, and even fewer went to college. Childhood, as it had existed in the prosperous twenties, was over. And yet, for many children living in rural areas where the affluence of the previous decade was not fully developed, the Depression was not viewed as a great challenge. School continued. Play was simple and enjoyed. Families adapted by growing more in gardens, canning, and preserving, wasting little food if any. Home-sewn clothing became the norm as the decade progressed, as did creative methods of shoe repair with cardboard soles. Yet, one always knew of stories of the “other” families who suffered more, including those living in cardboard boxes or caves. By one estimate, as many as 200,000 children moved about the country as vagrants due to familial disintegration.
Women’s lives, too, were profoundly affected. Some wives and mothers sought employment to make ends meet, an undertaking that was often met with strong resistance from husbands and potential employers. Many men derided and criticized women who worked, feeling that jobs should go to unemployed men. Some campaigned to keep companies from hiring married women, and an increasing number of school districts expanded the long-held practice of banning the hiring of married female teachers. Despite the pushback, women entered the workforce in increasing numbers, from ten million at the start of the Depression to nearly thirteen million by the end of the 1930s. This increase took place in spite of the twenty-six states that passed a variety of laws to prohibit the employment of married women. Several women found employment in the emerging pink collar occupations, viewed as traditional women’s work, including jobs as telephone operators, social workers, and secretaries. Others took jobs as maids and housecleaners, working for those fortunate few who had maintained their wealth.
White women’s forays into domestic service came at the expense of minority women, who had even fewer employment options. Unsurprisingly, African American men and women experienced unemployment, and the grinding poverty that followed, at double and triple the rates of their White counterparts. By 1932, unemployment among African Americans reached near 50 percent. In rural areas, where large numbers of African Americans continued to live despite the Great Migration of 1910–1930, depression-era life represented an intensified version of the poverty that they traditionally experienced. Subsistence farming allowed many African Americans who lost either their land or jobs working for White landholders to survive, but their hardships increased. Life for African Americans in urban settings was equally trying, with Black people and working-class White people living in close proximity and competing for scarce jobs and resources.
Life for all rural Americans was difficult. Farmers largely did not experience the widespread prosperity of the 1920s. Although continued advancements in farming techniques and agricultural machinery led to increased agricultural production, decreasing demand (particularly in the previous markets created by World War I) steadily drove down commodity prices. As a result, farmers could barely pay the debt they owed on machinery and land mortgages, and even then could do so only as a result of generous lines of credit from banks. While factory workers may have lost their jobs and savings in the crash, many farmers also lost their homes, due to the thousands of farm foreclosures sought by desperate bankers. Between 1930 and 1935, nearly 750,000 family farms disappeared through foreclosure or bankruptcy. Even for those who managed to keep their farms, there was little market for their crops. Unemployed workers had less money to spend on food, and when they did purchase goods, the market excess had driven prices so low that farmers could barely piece together a living. A now-famous example of the farmer’s plight is that, when the price of coal began to exceed that of corn, farmers would simply burn corn to stay warm in the winter.
As the effects of the Great Depression worsened, wealthier Americans had particular concern for “the deserving poor”—those who had lost all of their money due to no fault of their own. This concept gained greater attention beginning in the Progressive Era of the late nineteenth and early twentieth centuries, when early social reformers sought to improve the quality of life for all Americans by addressing the poverty that was becoming more prevalent, particularly in emerging urban areas. By the time of the Great Depression, social reformers and humanitarian agencies had determined that the “deserving poor” belonged to a different category from those who had speculated and lost. However, the sheer volume of Americans who fell into this group meant that charitable assistance could not begin to reach them all. Some fifteen million “deserving poor,” or a full one-third of the labor force, were struggling by 1932. The country had no mechanism or system in place to help so many; however, Hoover remained adamant that such relief should rest in the hands of private agencies, not with the federal government ().
Unable to receive aid from the government, Americans thus turned to private charities; churches, synagogues, and other religious organizations; and state aid. But these organizations were not prepared to deal with the scope of the problem. Private aid organizations showed declining assets as well during the Depression, with fewer Americans possessing the ability to donate to such charities. Likewise, state governments were particularly ill-equipped. Governor Franklin D. Roosevelt was the first to institute a Department of Welfare in New York in 1929. City governments had equally little to offer. In New York City in 1932, family allowances were $2.39 per week, and only one-half of the families who qualified actually received them. In Detroit, allowances fell to fifteen cents a day per person, and eventually ran out completely. In most cases, relief was only in the form of food and fuel; organizations provided nothing in the way of rent, shelter, medical care, clothing, or other necessities. There was no infrastructure to support the elderly, who were the most vulnerable, and this population largely depended on their adult children to support them, adding to families’ burdens ().
During this time, local community groups, such as police and teachers, worked to help the neediest. New York City police, for example, began contributing 1 percent of their salaries to start a food fund that was geared to help those found starving on the streets. In 1932, New York City schoolteachers also joined forces to try to help; they contributed as much as $250,000 per month from their own salaries to help needy children. Chicago teachers did the same, feeding some eleven thousand students out of their own pockets in 1931, despite the fact that many of them had not been paid a salary in months. These noble efforts, however, failed to fully address the level of desperation that the American public was facing.
### Section Summary
The prosperous decade leading up to the stock market crash of 1929, with easy access to credit and a culture that encouraged speculation and risk-taking, put into place the conditions for the country’s fall. The stock market, which had been growing for years, began to decline in the summer and early fall of 1929, precipitating a panic that led to a massive stock sell-off in late October. In one month, the market lost close to 40 percent of its value. Although only a small percentage of Americans had invested in the stock market, the crash affected everyone. Banks lost millions and, in response, foreclosed on business and personal loans, which in turn pressured customers to pay back their loans, whether or not they had the cash. As the pressure mounted on individuals, the effects of the crash continued to spread. The state of the international economy, the inequitable income distribution in the United States, and, perhaps most importantly, the contagion effect of panic all played roles in the continued downward spiral of the economy.
In the immediate aftermath of the crash, the government was confident that the economy would rebound. But several factors led it to worsen instead. One significant issue was the integral role of automobiles and construction in American industry. With the crash, there was no money for either auto purchases or major construction projects; these industries therefore suffered, laying off workers, cutting wages, and reducing benefits. Affluent Americans considered the deserving poor—those who lost their money due to no fault of their own—to be especially in need of help. But at the outset of the Great Depression, there were few social safety nets in place to provide them with the necessary relief. While some families retained their wealth and middle-class lifestyle, many more were plunged quite suddenly into poverty and often homelessness. Children dropped out of school, mothers and wives went into domestic service, and the fabric of American society changed inexorably.
### Review Questions
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# Brother, Can You Spare a Dime? The Great Depression, 1929-1932
## President Hoover’s Response
President Hoover was unprepared for the scope of the depression crisis, and his limited response did not begin to help the millions of Americans in need. The steps he took were very much in keeping with his philosophy of limited government, a philosophy that many had shared with him until the upheavals of the Great Depression made it clear that a more direct government response was required. But Hoover was stubborn in his refusal to give “handouts,” as he saw direct government aid. He called for a spirit of volunteerism among America’s businesses, asking them to keep workers employed, and he exhorted the American people to tighten their belts and make do in the spirit of “rugged individualism.” While Hoover’s philosophy and his appeal to the country were very much in keeping with his character, it was not enough to keep the economy from plummeting further into economic chaos.
The steps Hoover did ultimately take were too little, too late. He created programs for putting people back to work and helping beleaguered local and state charities with aid. But the programs were small in scale and highly specific as to who could benefit, and they only touched a small percentage of those in need. As the situation worsened, the public grew increasingly unhappy with Hoover. He left office with one of the lowest approval ratings of any president in history.
### THE INITIAL REACTION
In the immediate aftermath of Black Tuesday, Hoover sought to reassure Americans that all was well. Reading his words after the fact, it is easy to find fault. In 1929 he said, “Any lack of confidence in the economic future or the strength of business in the United States is foolish.” In 1930, he stated, “The worst is behind us.” In 1931, he pledged federal aid should he ever witness starvation in the country; but as of that date, he had yet to see such need in America, despite the very real evidence that children and the elderly were starving to death. Yet Hoover was neither intentionally blind nor unsympathetic. He simply held fast to a belief system that did not change as the realities of the Great Depression set in.
Hoover believed strongly in the ethos of American individualism: that hard work brought its own rewards. His life story testified to that belief. Hoover was born into poverty, made his way through college at Stanford University, and eventually made his fortune as an engineer. This experience, as well as his extensive travels in China and throughout Europe, shaped his fundamental conviction that the very existence of American civilization depended upon the moral fiber of its citizens, as evidenced by their ability to overcome all hardships through individual effort and resolve. The idea of government handouts to Americans was repellant to him. Whereas Europeans might need assistance, such as his hunger relief work in Belgium during and after World War I, he believed the American character to be different. In a 1931 radio address, he said, “The spread of government destroys initiative and thus destroys character.”
Likewise, Hoover was not completely unaware of the potential harm that wild stock speculation might create if left unchecked. As secretary of commerce, Hoover often warned President Coolidge of the dangers that such speculation engendered. In the weeks before his inauguration, he offered many interviews to newspapers and magazines, urging Americans to curtail their rampant stock investments, and even encouraged the Federal Reserve to raise the discount rate to make it more costly for local banks to lend money to potential speculators. However, fearful of creating a panic, Hoover never issued a stern warning to discourage Americans from such investments. Neither Hoover, nor any other politician of that day, ever gave serious thought to outright government regulation of the stock market. This was even true in his personal choices, as Hoover often lamented poor stock advice he had once offered to a friend. When the stock nose-dived, Hoover bought the shares from his friend to assuage his guilt, vowing never again to advise anyone on matters of investment.
In keeping with these principles, Hoover’s response to the crash focused on two very common American traditions: He asked individuals to tighten their belts and work harder, and he asked the business community to voluntarily help sustain the economy by retaining workers and continuing production. He immediately summoned a conference of leading industrialists to meet in Washington, DC, urging them to maintain their current wages while America rode out this brief economic panic. The crash, he assured business leaders, was not part of a greater downturn; they had nothing to worry about. Similar meetings with utility companies and railroad executives elicited promises for billions of dollars in new construction projects, while labor leaders agreed to withhold demands for wage increases and workers continued to labor. Hoover also persuaded Congress to pass a $160 million tax cut to bolster American incomes, leading many to conclude that the president was doing all he could to stem the tide of the panic. In April 1930, the New York Times editorial board concluded that “No one in his place could have done more.”
However, these modest steps were not enough. By late 1931, when it became clear that the economy would not improve on its own, Hoover recognized the need for some government intervention. He created the President’s Emergency Committee for Employment (PECE), later renamed the President’s Organization of Unemployment Relief (POUR). In keeping with Hoover’s distaste of what he viewed as handouts, this organization did not provide direct federal relief to people in need. Instead, it assisted state and private relief agencies, such as the Red Cross, Salvation Army, YMCA, and Community Chest. Hoover also strongly urged people of means to donate funds to help the poor, and he himself gave significant private donations to worthy causes. But these private efforts could not alleviate the widespread effects of poverty.
Congress pushed for a more direct government response to the hardship. In 1930–1931, it attempted to pass a $60 million bill to provide relief to drought victims by allowing them access to food, fertilizer, and animal feed. Hoover stood fast in his refusal to provide food, resisting any element of direct relief. The final bill of $47 million provided for everything except food but did not come close to adequately addressing the crisis. Again in 1931, Congress proposed the Federal Emergency Relief Bill, which would have provided $375 million to states to help provide food, clothing, and shelter to the homeless. But Hoover opposed the bill, stating that it ruined the balance of power between states and the federal government, and in February 1932, it was defeated by fourteen votes.
However, the president’s adamant opposition to direct-relief federal government programs should not be viewed as one of indifference or uncaring toward the suffering American people. His personal sympathy for those in need was boundless. Hoover was one of only two presidents to reject his salary for the office he held. Throughout the Great Depression, he donated an average of $25,000 annually to various relief organizations to assist in their efforts. Furthermore, he helped to raise $500,000 in private funds to support the White House Conference on Child Health and Welfare in 1930. Rather than indifference or heartlessness, Hoover’s steadfast adherence to a philosophy of individualism as the path toward long-term American recovery explained many of his policy decisions. “A voluntary deed,” he repeatedly commented, “is infinitely more precious to our national ideal and spirit than a thousand-fold poured from the Treasury.”
As conditions worsened, however, Hoover eventually relaxed his opposition to federal relief and formed the Reconstruction Finance Corporation (RFC) in 1932, in part because it was an election year and Hoover hoped to keep his office. Although not a form of direct relief to the American people in greatest need, the RFC was much larger in scope than any preceding effort, setting aside $2 billion in taxpayer money to rescue banks, credit unions, and insurance companies. The goal was to boost confidence in the nation’s financial institutions by ensuring that they were on solid footing. This model was flawed on a number of levels. First, the program only lent money to banks with sufficient collateral, which meant that most of the aid went to large banks. In fact, of the first $61 million loaned, $41 million went to just three banks. Small town and rural banks got almost nothing. Furthermore, at this time, confidence in financial institutions was not the primary concern of most Americans. They needed food and jobs. Many had no money to put into the banks, no matter how confident they were that the banks were safe.
Hoover’s other attempt at federal assistance also occurred in 1932, when he endorsed a bill by Senator Robert Wagner of New York. This was the Emergency Relief and Construction Act. This act authorized the RFC to expand beyond loans to financial institutions and allotted $1.5 billion to states to fund local public works projects. This program failed to deliver the kind of help needed, however, as Hoover severely limited the types of projects it could fund to those that were ultimately self-paying (such as toll bridges and public housing) and those that required skilled workers. While well intended, these programs maintained the status quo, and there was still no direct federal relief to the individuals who so desperately needed it.
### PUBLIC REACTION TO HOOVER
Hoover’s steadfast resistance to government aid cost him the reelection and has placed him squarely at the forefront of the most unpopular presidents, according to public opinion, in modern American history. His name became synonymous with the poverty of the era: “Hoovervilles” became the common name for homeless shantytowns () and “Hoover blankets” for the newspapers that the homeless used to keep warm. A “Hoover flag” was a pants pocket—empty of all money—turned inside out. By the 1932 election, hitchhikers held up signs reading: “If you don’t give me a ride, I’ll vote for Hoover.” Americans did not necessarily believe that Hoover caused the Great Depression. Their anger stemmed instead from what appeared to be a willful refusal to help regular citizens with direct aid that might allow them to recover from the crisis.
### FRUSTRATION AND PROTEST: A BAD SITUATION GROWS WORSE FOR HOOVER
Desperation and frustration often create emotional responses, and the Great Depression was no exception. Throughout 1931–1932, companies trying to stay afloat sharply cut worker wages, and, in response, workers protested in increasingly bitter strikes. As the Depression unfolded, over 80 percent of automotive workers lost their jobs. Even the typically prosperous Ford Motor Company laid off two-thirds of its workforce.
In 1932, a major strike at the Ford Motor Company factory near Detroit resulted in over sixty injuries and four deaths. Often referred to as the Ford Hunger March, the event unfolded as a planned demonstration among unemployed Ford workers who, to protest their desperate situation, marched nine miles from Detroit to the company’s River Rouge plant in Dearborn. At the Dearborn city limits, local police launched tear gas at the roughly three thousand protestors, who responded by throwing stones and clods of dirt. When they finally reached the gates of the plant, protestors faced more police and firemen, as well as private security guards. As the firemen turned hoses onto the protestors, the police and security guards opened fire. In addition to those killed and injured, police arrested fifty protestors. One week later, sixty thousand mourners attended the public funerals of the four victims of what many protesters labeled police brutality. The event set the tone for worsening labor relations in the U.S.
Farmers also organized and protested, often violently. The most notable example was the Farm Holiday Association. Led by Milo Reno, this organization held significant sway among farmers in Iowa, Nebraska, Wisconsin, Minnesota, and the Dakotas. Although they never comprised a majority of farmers in any of these states, their public actions drew press attention nationwide. Among their demands, the association sought a federal government plan to set agricultural prices artificially high enough to cover the farmers’ costs, as well as a government commitment to sell any farm surpluses on the world market. To achieve their goals, the group called for farm holidays, during which farmers would neither sell their produce nor purchase any other goods until the government met their demands. However, the greatest strength of the association came from the unexpected and seldom-planned actions of its members, which included barricading roads into markets, attacking nonmember farmers, and destroying their produce. Some members even raided small town stores, destroying produce on the shelves. Members also engaged in “penny auctions,” bidding pennies on foreclosed farm land and threatening any potential buyers with bodily harm if they competed in the sale. Once they won the auction, the association returned the land to the original owner. In Iowa, farmers threatened to hang a local judge if he signed any more farm foreclosures. At least one death occurred as a direct result of these protests before they waned following the election of Franklin Roosevelt.
One of the most notable protest movements occurred toward the end of Hoover’s presidency and centered on the Bonus Expeditionary Force, or Bonus Army, in the spring of 1932. In this protest, approximately fifteen thousand World War I veterans marched on Washington to demand early payment of their veteran bonuses, which were not due to be paid until 1945. The group camped out in vacant federal buildings and set up camps in Anacostia Flats near the Capitol building ().
Many veterans remained in the city in protest for nearly two months, although the U.S. Senate officially rejected their request in July. By the middle of that month, Hoover wanted them gone. He ordered the police to empty the buildings and clear out the camps, and in the exchange that followed, police fired into the crowd, killing two veterans. Fearing an armed uprising, Hoover then ordered General Douglas MacArthur, along with his aides, Dwight Eisenhower and George Patton, to forcibly remove the veterans from Anacostia Flats. The ensuing raid proved catastrophic, as the military burned down the shantytown and injured dozens of people, including a twelve-week-old infant who was killed when accidentally struck by a tear gas canister ().
As Americans bore witness to photographs and newsreels of the U.S. Army forcibly removing veterans, Hoover’s popularity plummeted even further. By the summer of 1932, he was largely a defeated man. His pessimism and failure mirrored that of the nation’s citizens. America was a country in desperate need: in need of a charismatic leader to restore public confidence as well as provide concrete solutions to pull the economy out of the Great Depression.
### Section Summary
President Hoover’s deeply held philosophy of American individualism, which he maintained despite extraordinary economic circumstances, made him particularly unsuited to deal with the crisis of the Great Depression. He greatly resisted government intervention, considering it a path to the downfall of American greatness. His initial response of asking Americans to find their own paths to recovery and seeking voluntary business measures to stimulate the economy could not stem the tide of the Depression. Ultimately, Hoover did create some federal relief programs, such as the Reconstruction Finance Corporation (RFC), which sought to boost public confidence in financial institutions by ensuring that they were on solid footing. When this measure did little to help impoverished individuals, he signed the Emergency Relief Act, which allowed the RFC to invest in local public works projects. But even this was too little, too late. The severe limits on the types of projects funded and type of workers used meant that most Americans saw no benefit.
The American public ultimately responded with anger and protest to Hoover’s apparent inability to create solutions. Protests ranged from factory strikes to farm riots, culminating in the notorious Bonus Army protest in the spring of 1932. Veterans from World War I lobbied to receive their bonuses immediately, rather than waiting until 1945. The government denied them, and in the ensuing chaos, Hoover called in the military to disrupt the protest. The violence of this act was the final blow for Hoover, whose popularity was already at an all-time low.
### Review Questions
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# Brother, Can You Spare a Dime? The Great Depression, 1929-1932
## The Depths of the Great Depression
From industrial strongholds to the rural Great Plains, from factory workers to farmers, the Great Depression affected millions. In cities, as industry slowed, then sometimes stopped altogether, workers lost jobs and joined breadlines, or sought out other charitable efforts. With limited government relief efforts, private charities tried to help, but they were unable to match the pace of demand. In rural areas, farmers suffered still more. In some parts of the country, prices for crops dropped so precipitously that farmers could not earn enough to pay their mortgages, losing their farms to foreclosure. In the Great Plains, one of the worst droughts in history left the land barren and unfit for growing even minimal food to live on.
The country’s most vulnerable populations, such as children, the elderly, and those subject to discrimination, like African Americans, were the hardest hit. Most White Americans felt entitled to what few jobs were available, leaving African Americans unable to find work, even in the jobs once considered their domain. In all, the economic misery was unprecedented in the country’s history.
### STARVING TO DEATH
By the end of 1932, the Great Depression had affected some sixty million people, most of whom wealthier Americans perceived as the “deserving poor.” Yet, at the time, federal efforts to help those in need were extremely limited, and national charities had neither the capacity nor the will to elicit the large-scale response required to address the problem. The American Red Cross did exist, but Chairman John Barton Payne contended that unemployment was not an “Act of God” but rather an “Act of Man,” and therefore refused to get involved in widespread direct relief efforts. Clubs like the Elks tried to provide food, as did small groups of individually organized college students. Religious organizations remained on the front lines, offering food and shelter. In larger cities, breadlines and soup lines became a common sight. At one count in 1932, there were as many as eighty-two breadlines in New York City.
Despite these efforts, however, people were destitute and ultimately starving. Families would first run through any savings, if they were lucky enough to have any. Then, the few who had insurance would cash out their policies. Cash surrender payments of individual insurance policies tripled in the first three years of the Great Depression, with insurance companies issuing total payments in excess of $1.2 billion in 1932 alone. When those funds were depleted, people would borrow from family and friends, and when they could get no more, they would simply stop paying rent or mortgage payments. When evicted, they would move in with relatives, whose own situation was likely only a step or two behind. The added burden of additional people would speed along that family’s demise, and the cycle would continue. This situation spiraled downward, and did so quickly. Even as late as 1939, over 60 percent of rural households, and 82 percent of farm families, were classified as “impoverished.” In larger urban areas, unemployment levels exceeded the national average, with over half a million unemployed workers in Chicago, and nearly a million in New York City. Breadlines and soup kitchens were packed, serving as many as eighty-five thousand meals daily in New York City alone. Over fifty thousand New York citizens were homeless by the end of 1932.
Children, in particular, felt the brunt of poverty. Many in coastal cities would roam the docks in search of spoiled vegetables to bring home. Elsewhere, children begged at the doors of more well-off neighbors, hoping for stale bread, table scraps, or raw potato peelings. Said one childhood survivor of the Great Depression, “You get used to hunger. After the first few days it doesn’t even hurt; you just get weak.” In 1931 alone, there were at least twenty documented cases of starvation; in 1934, that number grew to 110. In rural areas where such documentation was lacking, the number was likely far higher. And while the middle class did not suffer from starvation, they experienced hunger as well.
By the time Hoover left office in 1933, the poor survived not on relief efforts, but because they had learned to be poor. A family with little food would stay in bed to save fuel and avoid burning calories. People began eating parts of animals that had normally been considered waste. They scavenged for scrap wood to burn in the furnace, and when electricity was turned off, it was not uncommon to try and tap into a neighbor’s wire. Family members swapped clothes; sisters might take turns going to church in the one dress they owned. As one girl in a mountain town told her teacher, who had said to go home and get food, “I can’t. It’s my sister’s turn to eat.”
### BLACK AND POOR: AFRICAN AMERICANS AND THE GREAT DEPRESSION
Most African Americans did not participate in the land boom and stock market speculation that preceded the crash, but that did not stop the effects of the Great Depression from hitting them particularly hard. Subject to continuing racial discrimination, Black people nationwide fared even worse than their hard-hit White counterparts. As the prices for cotton and other agricultural products plummeted, farm owners paid workers less or simply laid them off. Landlords evicted sharecroppers, and even those who owned their land outright had to abandon it when there was no way to earn any income.
In cities, African Americans fared no better. Unemployment was rampant, and many White people felt that any available jobs should first go to them. In some Northern cities, White employees would conspire to have African American workers fired to allow White workers access to their jobs. Even jobs traditionally held by Black workers, such as household servants or janitors, were now going to White people. By 1932, approximately one-half of all Black Americans were unemployed. Racial violence also began to rise. In the South, lynching became more common again, with twenty-eight documented lynchings in 1933, compared to eight in 1932. Since communities were preoccupied with their own hardships, and organizing civil rights efforts was a long, difficult process, many resigned themselves to, or even ignored, this culture of racism and violence. Occasionally, however, an incident was notorious enough to gain national attention.
One such incident was the case of the Scottsboro Boys (). In 1931, nine Black boys, who had been riding the rails, were arrested for vagrancy and disorderly conduct after an altercation with some White travelers on the train. Two young White women, who had been dressed as boys and traveling with a group of White boys, came forward and said that the Black boys had raped them. The case, which was tried in Scottsboro, Alabama, illuminated decades of racial hatred and illustrated the injustice of the court system. Despite significant evidence that the women had not been raped at all, along with one of the women subsequently recanting her testimony, the all-White jury quickly convicted the boys and sentenced all but one of them to death. The verdict broke through the veil of indifference toward the plight of African Americans, and protests erupted among newspaper editors, academics, and social reformers in the North. The Communist Party of the United States offered to handle the case and sought retrial; the NAACP later joined in this effort. In all, the case was tried three separate times. The series of trials and retrials, appeals, and overturned convictions shone a spotlight on a system that provided poor legal counsel and relied on all-White juries. In October 1932, the U.S. Supreme Court agreed with the Communist Party’s defense attorneys that the defendants had been denied adequate legal representation at the original trial, and that due process as provided by the Fourteenth Amendment had been denied as a result of the exclusion of any potential Black jurors. Eventually, most of the accused received lengthy prison terms and subsequent parole, but avoided the death penalty. The Scottsboro case ultimately laid some of the early groundwork for the modern American civil rights movement. Alabama granted posthumous pardons to all defendants in 2013.
### ENVIRONMENTAL CATASTROPHE MEETS ECONOMIC HARDSHIP: THE DUST BOWL
Despite the widely held belief that rural Americans suffered less in the Great Depression due to their ability to at least grow their own food, this was not the case. Farmers, ranchers, and their families suffered more than any group other than African Americans during the Depression.
From the turn of the century through much of World War I, farmers in the Great Plains experienced prosperity due to unusually good growing conditions, high commodity prices, and generous government farming policies that led to a rush for land. As the federal government continued to purchase all excess produce for the war effort, farmers and ranchers fell into several bad practices, including mortgaging their farms and borrowing money against future production in order to expand. However, after the war, prosperity rapidly dwindled, particularly during the recession of 1921. Seeking to recoup their losses through economies of scale in which they would expand their production even further to take full advantage of their available land and machinery, farmers plowed under native grasses to plant acre after acre of wheat, with little regard for the long-term repercussions to the soil. Regardless of these misguided efforts, commodity prices continued to drop, finally plummeting in 1929, when the price of wheat dropped from two dollars to forty cents per bushel.
Exacerbating the problem was a massive drought that began in 1931 and lasted for eight terrible years. Dust storms roiled through the Great Plains, creating huge, choking clouds that piled up in doorways and filtered into homes through closed windows. Even more quickly than it had boomed, the land of agricultural opportunity went bust, due to widespread overproduction and overuse of the land, as well as to the harsh weather conditions that followed, resulting in the creation of the Dust Bowl ().
Livestock died, or had to be sold, as there was no money for feed. Crops intended to feed the family withered and died in the drought. Terrifying dust storms became more and more frequent, as “black blizzards” of dirt blew across the landscape and created a new illness known as “dust pneumonia.” In 1935 alone, over 850 million tons of topsoil blew away. To put this number in perspective, geologists estimate that it takes the earth five hundred years to naturally regenerate one inch of topsoil; yet, just one significant dust storm could destroy a similar amount. In their desperation to get more from the land, farmers had stripped it of the delicate balance that kept it healthy. Unaware of the consequences, they had moved away from such traditional practices as crop rotation and allowing land to regain its strength by permitting it to lie fallow between plantings, working the land to death.
For farmers, the results were catastrophic. Unlike most factory workers in the cities, in most cases, farmers lost their homes when they lost their livelihood. Most farms and ranches were originally mortgaged to small country banks that understood the dynamics of farming, but as these banks failed, they often sold rural mortgages to larger eastern banks that were less concerned with the specifics of farm life. With the effects of the drought and low commodity prices, farmers could not pay their local banks, which in turn lacked funds to pay the large urban banks. Ultimately, the large banks foreclosed on the farms, often swallowing up the small country banks in the process. It is worth noting that of the five thousand banks that closed between 1930 and 1932, over 75 percent were country banks in locations with populations under 2,500. Given this dynamic, it is easy to see why farmers in the Great Plains remained wary of big city bankers.
For farmers who survived the initial crash, the situation worsened, particularly in the Great Plains where years of overproduction and rapidly declining commodity prices took their toll. Prices continued to decline, and as farmers tried to stay afloat, they produced still more crops, which drove prices even lower. Farms failed at an astounding rate, and farmers sold out at rock-bottom prices. One farm in Shelby, Nebraska was mortgaged at $4,100 and sold for $49.50. One-fourth of the entire state of Mississippi was auctioned off in a single day at a foreclosure auction in April 1932.
Not all farmers tried to keep their land. Many, especially those who had arrived only recently, in an attempt to capitalize on the earlier prosperity, simply walked away (). In hard-hit Oklahoma, thousands of farmers packed up what they could and walked or drove away from the land they thought would be their future. They, along with other displaced farmers from throughout the Great Plains, became known as Okies. Okies were an emblem of the failure of the American breadbasket to deliver on its promise, and their story was made famous in John Steinbeck’s novel, The Grapes of Wrath.
### CHANGING VALUES, CHANGING CULTURE
In the decades before the Great Depression, and particularly in the 1920s, American culture largely reflected the values of individualism, self-reliance, and material success through competition. Novels like F. Scott Fitzgerald’s The Great Gatsby and Sinclair Lewis’s Babbit portrayed wealth and the self-made man in America, albeit in a critical fashion. In film, many silent movies, such as Charlie Chaplin’s The Gold Rush, depicted the rags-to-riches fable that Americans so loved. With the shift in U.S. fortunes, however, came a shift in values, and with it, a new cultural reflection. The arts revealed a new emphasis on the welfare of the whole and the importance of community in preserving family life. While box office sales briefly declined at the beginning of the Depression, they quickly rebounded. Movies offered a way for Americans to think of better times, and people were willing to pay twenty-five cents for a chance to escape, at least for a few hours.
Even more than escapism, other films at the close of the decade reflected on the sense of community and family values that Americans struggled to maintain throughout the entire Depression. John Ford’s screen version of Steinbeck’s The Grapes of Wrath came out in 1940, portraying the haunting story of the Joad family’s exodus from their Oklahoma farm to California in search of a better life. Their journey leads them to realize that they need to join a larger social movement—communism—dedicated to bettering the lives of all people. Tom Joad says, “Well, maybe it's like Casy says, a fella ain’t got a soul of his own, but on’y a piece of a soul—the one big soul that belongs to ever’body.” The greater lesson learned was one of the strength of community in the face of individual adversity.
Another trope was that of the hard-working everyman against greedy banks and corporations. This was perhaps best portrayed in the movies of Frank Capra, whose Mr. Smith Goes to Washington was emblematic of his work. In this 1939 film, Jimmy Stewart plays a legislator sent to Washington to finish out the term of a deceased senator. While there, he fights corruption to ensure the construction of a boy’s camp in his hometown rather than a dam project that would only serve to line the pockets of a few. He ultimately engages in a two-day filibuster, standing up to the power players to do what’s right. The Depression era was a favorite of Capra’s to depict in his films, including It’s a Wonderful Life, released in 1946. In this film, Jimmy Stewart runs a family-owned savings and loan, which at one point faces a bank run similar to those seen in 1929–1930. In the end, community support helps Stewart retain his business and home against the unscrupulous actions of a wealthy banker who sought to bring ruin to his family.
Finally, there was a great deal of pure escapism in the popular culture of the Depression. Even the songs found in films reminded many viewers of the bygone days of prosperity and happiness, from Al Dubin and Henry Warren’s hit “We’re in the Money” to the popular “Happy Days are Here Again.” The latter eventually became the theme song of Franklin Roosevelt’s 1932 presidential campaign. People wanted to forget their worries and enjoy the madcap antics of the Marx Brothers, the youthful charm of Shirley Temple, the dazzling dances of Fred Astaire and Ginger Rogers (), or the comforting morals of the Andy Hardy series. The Hardy series—nine films in all, produced by MGM from 1936 to 1940—starred Judy Garland and Mickey Rooney, and all followed the adventures of a small-town judge and his son. No matter what the challenge, it was never so big that it could not be solved with a musical production put on by the neighborhood kids, bringing together friends and family members in a warm display of community values.
All of these movies reinforced traditional American values, which suffered during these hard times, in part due to declining marriage and birth rates, and increased domestic violence. At the same time, however, they reflected an increased interest in sex and sexuality. While the birth rate was dropping, surveys in Fortune magazine in 1936–1937 found that two-thirds of college students favored birth control, and that 50 percent of men and 25 percent of women admitted to premarital sex, continuing a trend among younger Americans that had begun to emerge in the 1920s. Contraceptive sales soared during the decade, and again, culture reflected this shift. Blonde bombshell Mae West was famous for her sexual innuendoes, and her flirtatious persona was hugely popular, although it got her banned on radio broadcasts throughout the Midwest. Whether West or Garland, Chaplin or Stewart, American film continued to be a barometer of American values, and their challenges, through the decade.
### Section Summary
The Great Depression affected huge segments of the American population—sixty million people by one estimate. But certain groups were hit harder than the rest. African Americans faced discrimination in finding employment, as White workers sought even low-wage jobs like housecleaning. Southern Black people moved away from their farms as crop prices failed, migrating en masse to Northern cities, which had little to offer them. Rural Americans were also badly hit. The eight-year drought that began shortly after the stock market crash exacerbated farmers’ and ranchers’ problems. The cultivation of greater amounts of acreage in the preceding decades meant that land was badly overworked, and the drought led to massive and terrible dust storms, creating the region’s nickname, the Dust Bowl. Some farmers tried to remain and buy up more land as neighbors went broke; others simply fled their failed farms and moved away, often to the large-scale migrant farms found in California, to search for a better life that few ever found. Maltreated by Californians who wished to avoid the unwanted competition for jobs that these “Okies” represented, many of the Dust Bowl farmers were left wandering as a result.
There was very little in the way of public assistance to help the poor. While private charities did what they could, the scale of the problem was too large for them to have any lasting effects. People learned to survive as best they could by sending their children out to beg, sharing clothing, and scrounging wood to feed the furnace. Those who could afford it turned to motion pictures for escape. Movies and books during the Great Depression reflected the shift in American cultural norms, away from rugged individualism toward a more community-based lifestyle.
### Review Questions
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# Brother, Can You Spare a Dime? The Great Depression, 1929-1932
## Assessing the Hoover Years on the Eve of the New Deal
As so much of the Hoover presidency is circumscribed by the onset of the Great Depression, one must be careful in assessing his successes and failures, so as not to attribute all blame to Hoover. Given the suffering that many Americans endured between the fall of 1929 and Franklin Roosevelt’s inauguration in the spring of 1933, it is easy to lay much of the blame at Hoover’s doorstep (). However, the extent to which Hoover was constrained by the economic circumstances unfolding well before he assumed office offers a few mitigating factors. Put simply, Hoover did not cause the stock market crash. However, his stubborn adherence to a questionable belief in “American individualism,” despite mounting evidence that people were starving, requires that some blame be attributed to his policies (or lack thereof) for the depth and length of the Depression. Yet, Hoover’s presidency was much more than simply combating the Depression. To assess the extent of his inability to provide meaningful national leadership through the darkest months of the Depression, his other policies require consideration.
### HOOVER’S FOREIGN POLICY
Although it was a relatively quiet period for U.S. diplomacy, Hoover did help to usher in a period of positive relations, specifically with several Latin American neighbors. This would establish the basis for Franklin Roosevelt’s “Good Neighbor” policy. After a goodwill tour of Central American countries immediately following his election in 1928, Hoover shaped the subsequent Clark Memorandum—released in 1930—which largely repudiated the previous Roosevelt Corollary, establishing a basis for unlimited American military intervention throughout Latin America. To the contrary, through the memorandum, Hoover asserted that greater emphasis should be placed upon the older Monroe Doctrine, in which the U.S. pledged assistance to her Latin American neighbors should any European powers interfere in Western Hemisphere affairs. Hoover further strengthened relations to the south by withdrawing American troops from Haiti and Nicaragua. Additionally, he outlined with Secretary of State Henry Stimson the Hoover-Stimson Doctrine, which announced that the United States would never recognize claims to territories seized by force (a direct response to the recent Japanese invasion of Manchuria).
Other diplomatic overtures met with less success for Hoover. Most notably, in an effort to support the American economy during the early stages of the Depression, the president signed into law the Smoot-Hawley Tariff in 1930. The law, which raised tariffs on thousands of imports, was intended to increase sales of American-made goods, but predictably angered foreign trade partners who in turn raised their tariffs on American imports, thus shrinking international trade and closing additional markets to desperate American manufacturers. As a result, the global depression worsened further. A similar attempt to spur the world economy, known as the Hoover Moratorium, likewise met with great opposition and little economic benefit. Issued in 1931, the moratorium called for a halt to World War I reparations to be paid by Germany to France, as well as forgiveness of Allied war debts to the U.S.
### HOOVER AND CIVIL RIGHTS
Holding true to his belief in individualism, Hoover saw little need for significant civil rights legislation during his presidency, including any overtures from the NAACP to endorse federal anti-lynching legislation. He felt African Americans would benefit more from education and assimilation than from federal legislation or programs; yet he failed to recognize that, at this time in history, federal legislation and programs were required to ensure equal opportunities.
Hoover did give special attention to the improvement of Native American conditions, beginning with his selection of Charles Curtis as his vice-presidential running mate in the 1928 election. Curtis, of the Kaw Tribe, became the country’s first Native American to hold so high an elected office. Hoover subsequently appointed Charles Rhoads as the new commissioner of the Bureau of Indian Affairs and advocated, with Rhoads’ assistance, for Native American self-sufficiency and full assimilation as Americans under the Indian Citizenship Act of 1924. During Hoover’s presidency, federal expenditures for Native American schools and health care doubled.
### A FINAL ASSESSMENT
Herbert Hoover’s presidency, embarked upon with much promise following his election in November 1928, produced a legacy of mixed reactions. Some Americans blamed him for all of the economic and social woes from which they suffered for the next decade; all blamed him for simply not responding to their needs. As contemporary commentator and actor Will Rogers said at the time, “If an American was lucky enough to find an apple to eat in the Depression and bit into it only to find a worm, they would blame Hoover for the worm.” Likewise, subsequent public opinion polls of presidential popularity, as well as polls of professional historians, routinely rate Hoover in the bottom seven of all U.S. presidents in terms of overall success.
However, Hoover the president was a product of his time. Americans sought a president in 1928 who would continue the policies of normalcy with which many associated the prosperity they enjoyed. They wanted a president who would forego government interference and allow industrial capitalism to grow unfettered. Hoover, from his days as the secretary of commerce, was the ideal candidate. In fact, he was too ideal when the Great Depression actually hit. Holding steadfast to his philosophy of “American individualism,” Hoover proved largely incapable of shifting into economic crisis mode when Americans came to realize that prosperity could not last forever. Desperate to help, but unwilling to compromise on his philosophy, Hoover could not manage a comprehensive solution to the worldwide depression that few foresaw. Only when reelection was less than a year away did a reluctant Hoover initiate significant policies, but even then, they did not provide direct relief. By the start of 1932, unemployment hovered near 25 percent, and thousands of banks and factories were closing their doors. Combined with Hoover’s ill-timed response to the Bonus Army crisis, his political fate was sealed. Americans would look to the next president for a solution. “Democracy is a harsh employer,” Hoover concluded, as he awaited all but certain defeat in the November election of 1932 ().
### Section Summary
In Hoover, Americans got the president they had wanted, at least at first. He was third in a line of free-market Republican presidents, elected to continue the policies that had served the economy so well. But when the stock market crashed in 1929, and the underlying weaknesses in the economy came to the fore, Hoover did not act with clear intentionality and speed. His record as a president will likely always bear the taint of his unwillingness to push through substantial government aid, but, despite that failing, his record is not without minor accomplishments. Hoover’s international policies, particularly in regard to Latin America, served the country well. And while his attitude toward civil rights mirrored his conviction that government intervention was a negative force, he did play a key role changing living conditions for Native Americans. In all, it was his—and the country’s—bad luck that his presidency ultimately required a very different philosophy than the one that had gotten him elected.
### Review Questions
### Critical Thinking Questions
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# Franklin Roosevelt and the New Deal, 1932-1941
## Introduction
The election of President Franklin Delano Roosevelt signaled both immediate relief for the American public as well as a permanent shift in the role of the federal government in guiding the economy and providing direct assistance to the people, albeit through expensive programs that made extensive budget deficits commonplace. For many, the immediate relief was, at a minimum, psychological: Herbert Hoover was gone, and the situation could not grow worse under Roosevelt. But as his New Deal unfolded, Americans learned more about the fundamental changes their new president brought with him to the Oval Office. In the span of little more than one hundred days, the country witnessed a wave of legislation never seen before or since.
Roosevelt understood the need to “save the patient,” to borrow a medical phrase he often employed, as well as to “cure the ill.” This meant both creating jobs, through such programs as the Works Progress Administration, which provided employment to over eight million Americans (), as well as reconfiguring the structure of the American economy. In pursuit of these two goals, Americans re-elected Roosevelt for three additional terms in the White House and became full partners in the reshaping of their country. |
# Franklin Roosevelt and the New Deal, 1932-1941
## The Rise of Franklin Roosevelt
Franklin Roosevelt was part of the political establishment and the wealthy elite, but in the 1932 presidential campaign, he did not want to be perceived that way. Roosevelt felt that the country needed sweeping change, and he ran a campaign intended to convince the American people that he could deliver that change. It was not the specifics of his campaign promises that were different; in fact, he gave very few details and likely did not yet have a clear idea of how he would raise the country out of the Great Depression. But he campaigned tirelessly, talking to thousands of people, appearing at his party’s national convention, and striving to show the public that he was a different breed of politician. As Hoover grew more morose and physically unwell in the face of the campaign, Roosevelt thrived. He was elected in a landslide by a country ready for the change he had promised.
### THE ELECTION OF FRANKLIN ROOSEVELT
By the 1932 presidential election, Hoover’s popularity was at an all-time low. Despite his efforts to address the hardships that many Americans faced, his ineffectual response to the Great Depression left Americans angry and ready for change. Franklin Roosevelt, though born to wealth and educated at the best schools, offered the change people sought. His experience in politics had previously included a seat in the New York State legislature, a vice-presidential nomination, and a stint as governor of New York. During the latter, he introduced many state-level reforms that later formed the basis of his New Deal as well as worked with several advisors who later formed the Brains Trust that advised his federal agenda.
Roosevelt exuded confidence, which the American public desperately wished to see in their leader (). And, despite his affluence, Americans felt that he could relate to their suffering due to his own physical hardships; he had been struck with polio a decade earlier and was essentially paralyzed from the waist down for the remainder of his life. Roosevelt understood that the public sympathized with his ailment; he likewise developed a genuine empathy for public suffering as a result of his illness. However, he never wanted to be photographed in his wheelchair or appear infirm in any way, for fear that the public’s sympathy would transform into concern over his physical ability to discharge the duties of the Oval Office.
Roosevelt also recognized the need to convey to the voting public that he was not simply another member of the political aristocracy. At a time when the country not only faced its most severe economic challenges to date, but Americans began to question some of the fundamental principles of capitalism and democracy, Roosevelt sought to show that he was different—that he could defy expectations—and through his actions could find creative solutions to address the nation’s problems while restoring public confidence in fundamental American values. As a result, he not only was the first presidential candidate to appear in person at a national political convention to accept his party’s nomination but also flew there through terrible weather from New York to Chicago in order to do so—a risky venture in what was still the early stages of flight as public transportation. At the Democratic National Convention in 1932, he coined the famous phrase: “I pledge myself to a new deal for the American people.” The New Deal did not yet exist, but to the American people, any positive and optimistic response to the Great Depression was a welcome one.
Hoover assumed at first that Roosevelt would be easy to defeat, confident that he could never carry the eastern states and the business vote. He was sorely mistaken. Everywhere he went, Hoover was met with antagonism; anti-Hoover signs and protests were the norm. Hoover’s public persona declined rapidly. Many news accounts reported that he seemed physically unwell, with an ashen face and shaking hands. Often, he seemed as though he would faint, and an aide constantly remained nearby with a chair in case he fell. In contrast, Roosevelt thrived on the campaign. He commented, “I have looked into the faces of thousands of Americans, and they have the frightened look of lost children.”
The election results that November were never really in question: With three million more people voting than in 1928, Roosevelt won by a popular count of twenty-three million to fifteen million. He carried all but six states while winning over 57 percent of the popular vote. Whether they voted due to animosity towards Hoover for his relative inactivity, or out of hope for what Roosevelt would accomplish, the American public committed themselves to a new vision. Historians identify this election as the beginning of a new Democratic coalition, bringing together African Americans, other ethnic minorities, and organized labor as a voting bloc upon whom the party would rely for many of its electoral victories over the next fifty years. Unlike some European nations where similar challenges caused democratic constitutions to crumble and give way to radical ideologies and authoritarian governments, the Roosevelt administration changed the nation’s economic fortunes with reforms, preserved the constitution, and expanded rather than limited the reach of democratic principles into the market economy. As a result, radical alternatives, such as the Fascist movement or Communist Party, remained on the margins of the nation’s political culture.
### THE INTERREGNUM
After the landslide election, the country—and Hoover—had to endure the interregnum, the difficult four months between the election and President Roosevelt’s inauguration in March 1933. Congress did not pass a single significant piece of legislation during this period, although Hoover spent much of the time trying to get Roosevelt to commit publicly to a legislative agenda of Hoover’s choosing. Roosevelt remained gracious but refused to begin his administration as the incumbent’s advisor without any legal authority necessary to change policy. Unwilling to tie himself to Hoover’s legacy of failed policies, Roosevelt kept quiet when Hoover supported the passage of a national sales tax. Meanwhile, the country suffered from Hoover’s inability to further drive a legislative agenda through Congress. It was the worst winter since the beginning of the Great Depression, and the banking sector once again suffered another round of panics. While Roosevelt kept his distance from the final tremors of the Hoover administration, the country continued to suffer in wait. In part as a response to the challenges of this time, the U.S. Constitution was subsequently amended to reduce the period from election to inauguration to the now-commonplace two months.
Any ideas that Roosevelt held almost did not come to fruition, thanks to a would-be assassin’s bullet. On February 15, 1933, after delivering a speech from his open car in Miami’s Bayfront Park, local Italian bricklayer Giuseppe Zangara emerged from a crowd of well-wishers to fire six shots from his revolver. Although Roosevelt emerged from the assassination attempt unscathed, Zangara wounded five individuals that day, including Chicago Mayor Tony Cermak, who attended the speech in the hopes of resolving any long-standing differences with the president-elect. Roosevelt and his driver immediately rushed Cermak to the hospital where he died 19 days later. Roosevelt’s calm and collected response to the event reassured many Americans of his ability to lead the nation through the challenges they faced. All that awaited was Roosevelt’s inauguration before his ideas would unfold to the expectant public.
So what was Roosevelt’s plan? Before he took office, it seems likely that he was not entirely sure. Certain elements were known: He believed in positive government action to solve the Depression; he believed in federal relief, public works, social security, and unemployment insurance; he wanted to restore public confidence in banks; he wanted stronger government regulation of the economy; and he wanted to directly help farmers. But how to take action on these beliefs was more in question. A month before his inauguration, he said to his advisors, “Let’s concentrate upon one thing: Save the people and the nation, and if we have to change our minds twice every day to accomplish that end, we should do it.”
Unlike Hoover, who professed an ideology of “American individualism,” an adherence that rendered him largely incapable of widespread action, Roosevelt remained pragmatic and open-minded to possible solutions. To assist in formulating a variety of relief and recovery programs, Roosevelt turned to a group of men who had previously orchestrated his election campaign and victory. Collectively known as the “Brains Trust” (a phrase coined by a New York Times reporter to describe the multiple “brains” on Roosevelt’s advisory team), the group most notably included Rexford Tugwell, Raymond Moley, and Adolph Berle. Moley, credited with bringing the group into existence, was a government professor who advocated for a new national tax policy to help the nation recover from its economic woes. Tugwell, who eventually focused his energy on the country’s agricultural problems, saw an increased role for the federal government in setting wages and prices across the economy. Berle was a mediating influence, who often advised against a centrally controlled economy, but did see the role that the federal government could play in mediating the stark cycles of prosperity and depression that, if left unchecked, could result in the very situation in which the country presently found itself. Together, these men, along with others, advised Roosevelt through the earliest days of the New Deal and helped to craft significant legislative programs for congressional review and approval.
### INAUGURATION DAY: A NEW BEGINNING
March 4, 1933, dawned gray and rainy. Roosevelt rode in an open car along with outgoing president Hoover, facing the public, as he made his way to the U.S. Capitol. Hoover’s mood was somber, still personally angry over his defeat in the general election the previous November; he refused to crack a smile at all during the ride among the crowd, despite Roosevelt’s urging to the contrary. At the ceremony, Roosevelt rose with the aid of leg braces equipped under his specially tailored trousers and placed his hand on a Dutch family Bible as he took his solemn oath. At that very moment, the rain stopped and the sun began to shine directly on the platform, and those present would later claim that it was as though God himself was shining down on Roosevelt and the American people in that moment ().
Bathed in the sunlight, Roosevelt delivered one of the most famous and oft-quoted inaugural addresses in history. He encouraged Americans to work with him to find solutions to the nation’s problems and not to be paralyzed by fear into inaction. Borrowing a wartime analogy provided by Moley, who served as his speechwriter at the time, Roosevelt called upon all Americans to assemble and fight an essential battle against the forces of economic depression. He famously stated, “The only thing we have to fear is fear itself.” Upon hearing his inaugural address, one observer in the crowd later commented, “Any man who can talk like that in times like these is worth every ounce of support a true American has.” To borrow the popular song title of the day, “happy days were here again.” Foregoing the traditional inaugural parties, the new president immediately returned to the White House to begin his work to save the nation.
### Section Summary
Franklin Roosevelt was a wealthy, well-educated, and popular politician whose history of polio made him a more sympathetic figure to the public. He did not share any specifics of his plan to bring the country out of the Great Depression, but his attitude of optimism and possibility contrasted strongly with Hoover’s defeated misery. The 1932 election was never really in question, and Roosevelt won in a landslide. During the four-month interregnum, however, Americans continued to endure President Hoover’s failed policies, which led the winter of 1932–1933 to be the worst of the Depression, with unemployment rising to record levels.
When Roosevelt took office in March 1933, he infused the country with a sense of optimism. He still did not have a formal plan but rather invited the American people to join him in the spirit of experimentation. Roosevelt did bring certain beliefs to office: the belief in an active government that would take direct action on federal relief, public works, social services, and direct aid to farmers. But as much as his policies, Roosevelt’s own personality and engaging manner helped the country feel that they were going to get back on track.
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# Franklin Roosevelt and the New Deal, 1932-1941
## The First New Deal
Much like a surgeon assessing the condition of an emergency room patient, Roosevelt began his administration with a broad, if not specific, strategy in mind: a combination of relief and recovery programs designed to first save the patient (in this case, the American people), and then to find a long-term cure (reform through federal regulation of the economy). What later became known as the “First New Deal” ushered in a wave of legislative activity seldom before seen in the history of the country. By the close of 1933, in an effort to stem the crisis, Congress had passed over fifteen significant pieces of legislation—many of the circulated bills allegedly still wet with ink from the printing presses as members voted upon them. Most bills could be grouped around issues of relief, recovery, and reform. At the outset of the First New Deal, specific goals included 1) bank reform; 2) job creation; 3) economic regulation; and 4) regional planning.
### REFORM: THE BANKING CRISIS
When Roosevelt took office, he faced one of the worst moments in the country’s banking history. States were in disarray. New York and Illinois had ordered the closure of their banks in the hopes of avoiding further “bank runs,” which occurred when hundreds (if not thousands) of individuals ran to their banks to withdraw all of their savings. In all, over five thousand banks had been shuttered. Within forty-eight hours of his inauguration, Roosevelt proclaimed an official bank holiday and called Congress into a special session to address the crisis. The resulting Emergency Banking Act of 1933 was signed into law on March 9, 1933, a scant eight hours after Congress first saw it. The law officially took the country off the gold standard, a restrictive practice that, although conservative and traditionally viewed as safe, severely limited the circulation of paper money. Those who held gold were told to sell it to the U.S. Treasury for a discounted rate of a little over twenty dollars per ounce. Furthermore, dollar bills were no longer redeemable in gold. The law also gave the comptroller of currency the power to reorganize all national banks faced with insolvency, a level of federal oversight seldom seen prior to the Great Depression. Between March 11 and March 14, auditors from the Reconstruction Finance Corporation, the Treasury Department, and other federal agencies swept through the country, examining each bank. By March 15, 70 percent of the banks were declared solvent and allowed to reopen.
On March 12, the day before the banks were set to reopen, Roosevelt held his first “fireside chat” (). In this initial radio address to the American people, he explained what the bank examiners had been doing over the previous week. He assured people that any bank open the next day had the federal government’s stamp of approval. The combination of his reassuring manner and the promise that the government was addressing the problems worked wonders in changing the popular mindset. Just as the culture of panic had contributed to the country’s downward spiral after the crash, so did this confidence-inducing move help to build it back up. Consumer confidence returned, and within weeks, close to $1 billion in cash and gold had been brought out from under mattresses and hidden bookshelves, and re-deposited in the nation’s banks. The immediate crisis had been quelled, and the public was ready to believe in their new president.
In June 1933, Roosevelt replaced the Emergency Banking Act with the more permanent Glass-Steagall Banking Act. This law prohibited commercial banks from engaging in investment banking, therefore stopping the practice of banks speculating in the stock market with deposits. This law also created the Federal Deposit Insurance Corporation, or FDIC, which insured personal bank deposits up to $2,500. Other measures designed to boost confidence in the overall economy beyond the banking system included passage of the Economy Act, which fulfilled Roosevelt’s campaign pledge to reduce government spending by reducing salaries, including his own and those of the Congress. He also signed into law the Securities Act, which required full disclosure to the federal government from all corporations and investment banks that wanted to market stocks and bonds. Roosevelt also sought new revenue through the Beer Tax. As the Twenty-First Amendment, which would repeal the Eighteenth Amendment establishing Prohibition, moved towards ratification, this law authorized the manufacture of 3.2 percent beer and levied a tax on it.
### THE FIRST HUNDRED DAYS
In his first hundred days in office, the new president pushed forward an unprecedented number of new bills, all geared towards stabilizing the economy, providing relief to individuals, creating jobs, and helping businesses. A sympathetic Democrat-controlled Congress helped propel his agenda forward.
### Relief: Employment for the Masses
Even as he worked to rebuild the economy, Roosevelt recognized that the unemployed millions required jobs more quickly than the economy could provide. In a push to create new jobs, Roosevelt signed the Wagner-Peyser Act, creating the United States Employment Service, which promised states matching funds if they created local employment opportunities. He also authorized $500 million in direct grants through the Federal Emergency Relief Act (FERA). This money went directly to states to infuse relief agencies with the much-needed resources to help the nearly fifteen million unemployed. These two bills illustrate Roosevelt’s dual purposes of providing short-term emergency help and building employment opportunities that would strengthen the economy in the long term.
Roosevelt was aware of the need for immediate help, but he mostly wanted to create more jobs. FERA overseer Harry Hopkins, who later was in charge of the Civil Works Administration (CWA), shared this sentiment. With Hopkins at its helm, the CWA, founded in early 1933, went on to put millions of men and women to work. At its peak, there were some four million Americans repairing bridges, building roads and airports, and undertaking other public projects. Another work program was the Civilian Conservation Corps Relief Act (CCC). The CCC provided government jobs for young men aged fourteen to twenty-four who came from relief families. They would earn thirty dollars per month planting trees, fighting forest fires, and refurbishing historic sites and parks, building an infrastructure that families would continue to enjoy for generations to come. Within the first two months, the CCC employed its first 250,000 men and eventually established about twenty-five hundred camps ().
The various programs that made up the First New Deal are listed in the table below ().
The final element of Roosevelt’s efforts to provide relief to those in desperate straits was the Home Owners’ Refinancing Act. Created by the Home Owners’ Loan Corporation (HOLC), the program rescued homeowners from foreclosure by refinancing their mortgages. Not only did this save the homes of countless homeowners, but it also saved many of the small banks who owned the original mortgages by relieving them of the refinancing responsibility. Later New Deal legislation created the Federal Housing Authority, which eventually standardized the thirty-year mortgage and promoted the housing boom of the post-World War II era. A similar program, created through the Emergency Farm Mortgage Act and Farm Credit Act, provided the same service for farm mortgages.
### Rescuing Farms and Factories
While much of the legislation of the first hundred days focused on immediate relief and job creation through federal programs, Roosevelt was committed to addressing the underlying problems inherent in the American economy. In his efforts to do so, he created two of the most significant pieces of New Deal legislation: the Agricultural Adjustment Act (AAA) and the National Industry Recovery Act (NIRA).
Farms around the country were suffering, but from different causes. In the Great Plains, drought conditions meant that little was growing at all, while in the South, bumper crops and low prices meant that farmers could not sell their goods at prices that could sustain them. The AAA offered some direct relief: Farmers received $4.5 million through relief payments. But the larger part of the program paid southern farmers to reduce their production: Wheat, cotton, corn, hogs, tobacco, rice, and milk farmers were all eligible. Passed into law on May 12, 1933, it was designed to boost prices to a level that would alleviate rural poverty and restore profitability to American agriculture. These price increases would be achieved by encouraging farmers to limit production in order to increase demand while receiving cash payments in return. Corn producers would receive thirty cents per bushel for corn they did not grow. Hog farmers would get five dollars per head for hogs not raised. The program would be financed by a tax on processing plants, passed on to consumers in the form of higher prices.
This was a bold attempt to help farmers address the systemic problems of overproduction and lower commodity prices. Despite previous efforts to regulate farming through subsidies, never before had the federal government intervened on this scale; the notion of paying farmers not to produce crops was unheard of. One significant problem, however, was that, in some cases, there was already an excess of crops, in particular, cotton and hogs, which clogged the marketplace. A bumper crop in 1933, combined with the slow implementation of the AAA, led the government to order the plowing under of ten million acres of cotton, and the butchering of six million baby pigs and 200,000 sows. Although it worked to some degree—the price of cotton increased from six to twelve cents per pound—this move was deeply problematic. Critics saw it as the ultimate example of corrupt capitalism: a government destroying food, while its citizens were starving, in order to drive up prices.
Another problem plaguing this relief effort was the disparity between large commercial farms, which received the largest payments and set the quotas, and the small family farms that felt no relief. Large farms often cut production by laying off sharecroppers or evicting tenant farmers, making the program even worse for them than for small farm owners. Their frustration led to the creation of the Southern Tenant Farmers Union (STFU), an interracial organization that sought to gain government relief for these most disenfranchised of farmers. The STFU organized, protested, and won its members some wage increases through the mid-1930s, but the overall plight of these workers remained dismal. As a result, many of them followed the thousands of Dust Bowl refugees to California ().
The AAA did succeed on some fronts. By the spring of 1934, farmers had formed over four thousand local committees, with more than three million farmers agreeing to participate. They signed individual contracts agreeing to take land out of production in return for government payments, and checks began to arrive by the end of 1934. For some farmers, especially those with large farms, the program spelled relief.
While Roosevelt hoped the AAA would help farms and farmers, he also sought aid for the beleaguered manufacturing sector. The Emergency Railroad Transportation Act created a national railroad office to encourage cooperation among different railroad companies, hoping to shore up an industry essential to the stability of the manufacturing sector, but one that had been devastated by mismanagement. More importantly, the NIRA suspended antitrust laws and allowed businesses and industries to work together in order to establish codes of fair competition, including issues of price setting and minimum wages. New Deal officials believed that allowing these collaborations would help industries stabilize prices and production levels in the face of competitive overproduction and declining profits; however, at the same time, many felt it important to protect workers from potentially unfair agreements.
A new government agency, the National Recovery Administration (NRA), was central to this plan, and mandated that businesses accept a code that included minimum wages and maximum work hours. In order to protect workers from potentially unfair agreements among factory owners, every industry had its own “code of fair practice” that included workers’ rights to organize and use collective bargaining to ensure that wages rose with prices (). Headed by General Hugh S. Johnson, the NRA worked to create over five hundred different codes for different industries. The administration of such a complex plan naturally created its own problems. While codes for key industries such as automotive and steel made sense, Johnson pushed to create similar codes for dog food manufacturers, those who made shoulder pads for women’s clothing, and even burlesque shows (regulating the number of strippers in any one show).
The NIRA also created the Public Works Administration (PWA). The PWA set aside $3.3 billion to build public projects such as highways, federal buildings, and military bases. Although this program suffered from political squabbles over appropriations for projects in various congressional districts, as well as significant underfunding of public housing projects, it ultimately offered some of the most lasting benefits of the NIRA. Secretary of the Interior Harold Ickes ran the program, which completed over thirty-four thousand projects, including the Golden Gate Bridge in San Francisco and the Queens-Midtown Tunnel in New York. Between 1933 and 1939, the PWA accounted for the construction of over one-third of all new hospitals and 70 percent of all new public schools in the country.
Another challenge faced by the NRA was that the provision granting workers the right to organize appeared to others as a mandate to do so. In previously unorganized industries, such as oil and gas, rubber, and service occupations, workers now sought groups that would assist in their organization, bolstered by the encouragement they now felt from the government. The Communist Party took advantage of the opportunity to assist in the hope of creating widespread protests against the American industrial structure. The number of strikes nationwide doubled between 1932 and 1934, with over 1.5 million workers going on strike in 1934 alone, often in protests that culminated in bloodshed. A strike at the Auto-Lite plant in Toledo, Ohio, that summer resulted in ten thousand workers from other factories joining in sympathy with their fellow workers to attack potential strike-breakers with stones and bricks. Simultaneously in Minneapolis, a teamsters strike resulted in frequent, bloody confrontations between workers and police, leading the governor to contemplate declaring martial law before the companies agreed to negotiate better wages and conditions for the workers. Finally, a San Francisco strike among 14,000 longshoremen closed the city’s waterfront and eventually led to a city-wide general strike of over 130,000 workers, essentially paralyzing the city. Clashes between workers, and police and National Guardsmen left many strikers bloodied, and at least two dead.
Although Roosevelt’s relief efforts provided jobs to many and benefitted communities with the construction of several essential building projects, the violence that erupted amid clashes between organized labor and factories backed by police and the authorities exposed a fundamental flaw in the president’s approach. Immediate relief did not address long-existing, inherent class inequities that left workers exposed to poor working conditions, low wages, long hours, and little protection. For many workers, life on the job was not much better than life as an unemployed American. Employment programs may have put men back to work and provided much needed relief, but the fundamental flaws in the system required additional attention—attention that Roosevelt was unable to pay in the early days of the New Deal. Critics were plentiful, and the president would be forced to address them in the years ahead.
### Regional Planning
Regionally, Roosevelt’s work was most famously seen in the Tennessee Valley Authority (TVA) (), a federal agency tasked with the job of planning and developing the area through flood control, reforestation, and hydroelectric power. Employing several thousand Americans on a project that Roosevelt envisioned as a template for future regional redevelopment, the TVA revitalized a river valley that landowners had badly over-farmed, leaving behind eroded soil that lacked essential nutrients for future farming. Under the direction of David Lilienthal, beginning in 1933, the TVA workers erected a series of dams to harness the Tennessee River in the creation of much-needed hydroelectric power. The arrival of both electric lighting and machinery to the region eased the lives of the people who lived there, as well as encouraged industrial growth. The TVA also included an educational component, teaching farmers important lessons about crop rotation, soil replenishment, fertilizing, and reforestation.
The TVA was not without its critics, however, most notably among the fifteen thousand families who were displaced due to the massive construction projects. Although eventually the project benefited farmers with the introduction of new farming and fertilizing techniques, as well as the added benefit of electric power, many local citizens were initially mistrustful of the TVA and the federal government’s agenda. Likewise, as with several other New Deal programs, women did not directly benefit from these employment opportunities, as they were explicitly excluded for the benefit of men who most Americans still considered the family’s primary breadwinner. However, with the arrival of electricity came new industrial ventures, including several textile mills up and down the valley, several of which offered employment to women. Throughout his presidency, Roosevelt frequently pointed to the TVA as one of the glowing accomplishments of the New Deal and its ability to bring together the machinery of the federal government along with private interests to revitalize a regional economy. Just months before his death in 1945, he continued to speak of the possibility of creating other regional authorities throughout the country.
### ASSESSING THE FIRST NEW DEAL
While many were pleased with the president’s bold plans, there were numerous critics of the New Deal, discussed in the following section. The New Deal was far from perfect, but Roosevelt’s quickly implemented policies reversed the economy’s long slide. It put new capital into ailing banks. It rescued homeowners and farmers from foreclosure and helped people keep their homes. It offered some direct relief to the unemployed poor. It gave new incentives to farmers and industry alike, and put people back to work in an effort to both create jobs and boost consumer spending. The total number of working Americans rose from twenty-four to twenty-seven million between 1933 and 1935, in contrast to the seven-million-worker decline during the Hoover administration. Perhaps most importantly, the First New Deal changed the pervasive pessimism that had held the country in its grip since the end of 1929. For the first time in years, people had hope.
It was the hard work of Roosevelt’s advisors—the “Brains Trust” of scholars and thinkers from leading universities—as well as Congress and the American public who helped the New Deal succeed as well as it did. Ironically, it was the American people’s volunteer spirit, so extolled by Hoover, that Roosevelt was able to harness. The first hundred days of his administration was not a master plan that Roosevelt dreamed up and executed on his own. In fact, it was not a master plan at all, but rather a series of, at times, disjointed efforts made from different assumptions. But after taking office and analyzing the crisis, Roosevelt and his advisors did feel that they had a larger sense of what had caused the Great Depression and thus attempted a variety of solutions to fix it. They believed that it was caused by abuses on the part of a small group of bankers and businessmen, aided by Republican policies that built wealth for a few at the expense of many. The answer, they felt, was to root out these abuses through banking reform, as well as adjust production and consumption of both farm and industrial goods. This adjustment would come about by increasing the purchasing power of everyday people, as well as through regulatory policies like the NRA and AAA. While it may seem counterintuitive to raise crop prices and set prices on industrial goods, Roosevelt’s advisors sought to halt the deflationary spiral and economic uncertainty that had prevented businesses from committing to investments and consumers from parting with their money.
### Section Summary
After assuming the presidency, Roosevelt lost no time in taking bold steps to fight back against the poverty and unemployment plaguing the country. He immediately created a bank holiday and used the time to bring before Congress legislation known as the Emergency Banking Act, which allowed federal agencies to examine all banks before they reopened, thus restoring consumer confidence. He then went on, in his historic first hundred days, to sign numerous other significant pieces of legislation that were geared towards creating jobs, shoring up industry and agriculture, and providing relief to individuals through both refinancing options and direct handouts. Not all of his programs were effective, and many generated significant criticism. Overall, however, these programs helped to stabilize the economy, restore confidence, and change the pessimistic mindset that had overrun the country.
### Review Questions
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# Franklin Roosevelt and the New Deal, 1932-1941
## The Second New Deal
Roosevelt won his second term in a landslide, but that did not mean he was immune to criticism. His critics came from both the left and the right, with conservatives deeply concerned over his expansion of government spending and power, and liberals angered that he had not done more to help those still struggling. Adding to Roosevelt’s challenges, the Supreme Court struck down several key elements of the First New Deal, angering Roosevelt and spurring him to try and stack the courts in his second term. Still, he entered his new term with the unequivocal support of the voting public, and he wasted no time beginning the second phase of his economic plan. While the First New Deal focused largely on stemming the immediate suffering of the American people, the Second New Deal put in place legislation that changed America’s social safety net for good.
### CHALLENGES FROM CRITICS ON ALL SIDES
While many people supported Roosevelt, especially in the first few years of his presidency, the New Deal did receive significant criticism, both from conservatives who felt that it was a radical agenda to ruin the country’s model of free enterprise, and from liberals who felt that it did not provide enough help to those who needed it most ().
Industrialists and wealthy Americans led the conservative criticism against the president. Whether attacking his character or simply stating that he was moving away from American values toward fascism and socialism, they sought to undermine his power and popularity. Most notably, the American Liberty League—comprised largely of conservative Democrats who lamented the excesses of several of Roosevelt’s New Deal programs—labeled the AAA as fascist and proclaimed later New Deal programs to be key threats to the very nature of democracy. Additional criticism came from the National Association of Manufacturers, which urged businessmen to outright ignore portions of the NRA that promoted collective bargaining, as well as subsequent labor protection legislation. In 1935, the U.S. Supreme Court dealt the most crushing blow to Roosevelt’s vision, striking down several key pieces of the New Deal as unconstitutional. They found that both the AAA and the NIRA overreached federal authority. The negation of some of his most ambitious economic recovery efforts frustrated Roosevelt greatly, but he was powerless to stop it at this juncture.
Meanwhile, others felt that Roosevelt had not done enough. Dr. Francis E. Townsend of California was one who felt that Roosevelt had failed to adequately address the country’s tremendous problems. Townsend, who was a retired dentist, proposed an expansive pension plan for the elderly. The Townsend Plan, as it was known, gained a great deal of popularity: It recommended paying every citizen over sixty who retired from work the sum of $200 per month, provided they spend it in thirty days. Another figure who gained national attention was Father Charles Coughlin. He was a “radio priest” from Michigan who, although he initially supported the New Deal, subsequently argued that Roosevelt stopped far too short in his defense of labor, monetary reform, and the nationalization of key industries. The president’s plan, he proclaimed, was inadequate. He created the National Union for Social Justice and used his weekly radio show to gain followers.
A more direct political threat to Roosevelt came from muckraker Upton Sinclair, who pursued the California governorship in 1934 through a campaign based upon criticism of the New Deal’s shortcomings. In his “End Poverty in California” program, Sinclair called for a progressive income tax, a pension program for the elderly, and state seizure of factories and farms where property taxes remained unpaid. The state would then offer jobs to the unemployed to work those farms and factories in a cooperative mode. Although Sinclair lost the election to his Republican opponent, he did draw local and national attention to several of his ideas.
The biggest threat to the president, however, came from corrupt but beloved Louisiana senator Huey “Kingfish” Long (). His disapproval of Roosevelt came in part from his own ambitions for higher office; Long stated that the president was not doing enough to help people and proposed his own Share Our Wealth program. Under this plan, Long recommended the liquidation of all large personal fortunes in order to fund direct payments to less fortunate Americans. He foresaw giving $5,000 to every family, $2,500 to every worker, as well as a series of elderly pensions and education funds. Despite his questionable math, which numerous economists quickly pointed out rendered his program unworkable, by 1935, Long had a significant following of over four million people. If he had not been assassinated by the son-in-law of a local political rival, he may well have been a contender against Roosevelt for the 1936 presidential nomination.
### ANSWERING THE CHALLENGE
Roosevelt recognized that some of the criticisms of the New Deal were valid. Although he was still reeling from the Supreme Court’s invalidation of key statutes, he decided to face his re-election bid in 1936 by unveiling another wave of legislation that he dubbed the Second New Deal. In the first week of June 1935, Roosevelt called congressional leaders into the White House and gave them a list of “must-pass” legislation that he wanted before they adjourned for the summer. Whereas the policies of the first hundred days may have shored up public confidence and stopped the most drastic of the problems, the second hundred days changed the face of America for the next sixty years.
The Banking Act of 1935 was the most far-reaching revision of banking laws since the creation of the Federal Reserve System in 1914. Previously, regional reserve banks, particularly the New York Reserve Bank—controlled by the powerful Morgan and Rockefeller families—had dominated policy-making at the Federal Reserve. Under the new system, there would be a seven-member board of governors to oversee regional banks. They would have control over reserve requirements, discount rates, board member selection, and more. Not surprisingly, this new board kept initial interest rates quite low, allowing the federal government to borrow billions of dollars of additional cash to fund major relief and recovery programs.
In 1935, Congress also passed the Emergency Relief Appropriation Act, which authorized the single largest expenditure at that time in the country’s history: $4.8 billion. Almost one-third of those funds were invested in a new relief agency, the Works Progress Administration (WPA). Harry Hopkins, formerly head of the CWA, took on the WPA and ran it until 1943. In that time, the program provided employment relief to over eight million Americans, or approximately 20 percent of the country’s workforce. The WPA funded the construction of more than 2,500 hospitals, 5,900 schools, 570,000 miles of road, and more. The WPA also created Federal Project Number One, which employed approximately forty thousand artists in theater, art, music, and writing. They produced state murals, guidebooks, concerts, and drama performances all around the country (). Additionally, the project funded the collection of oral histories, including those of formerly enslaved people, which provided a valuable addition to the nation’s understanding of slave life. Finally, the WPA also included the National Youth Administration (NYA), which provided work-study jobs to over 500,000 college students and four million high school students.
With the implementation of the Second New Deal, Roosevelt also created the country’s present-day social safety net. The Social Security Act established programs intended to help the most vulnerable: the elderly, the unemployed, the disabled, and the young. It included a pension fund for all retired people—except domestic workers and farmers, which therefore left many women and African Americans beyond the scope of its benefits—over the age of sixty-five, to be paid through a payroll tax on both employee and employer. Related to this act, Congress also passed a law on unemployment insurance, to be funded by a tax on employers, and programs for unwed mothers, as well as for those who were blind, deaf, or disabled. It is worth noting that some elements of these reforms were pulled from Roosevelt detractors Coughlin and Townsend; the popularity of their movements gave the president more leverage to push forward this type of legislation.
To the benefit of industrial workers, Roosevelt signed into law the Wagner Act, also known as the National Labor Relations Act. The protections previously afforded to workers under the NIRA were inadvertently lost when the Supreme Court struck down the original law due to larger regulatory concerns, leaving workers vulnerable. Roosevelt sought to salvage this important piece of labor legislation, doing so with the Wagner Act. The act created the National Labor Relations Board (NLRB) to once again protect American workers’ right to unionize and bargain collectively, as well as to provide a federal vehicle for labor grievances to be heard. Although roundly criticized by the Republican Party and factory owners, the Wagner Act withstood several challenges and eventually received constitutional sanction by the U.S. Supreme Court in 1937. The law received the strong support of John L. Lewis and the Congress of Industrial Organizations who had long sought government protection of industrial unionism, from the time they split from the American Federation of Labor in 1935 over disputes on whether to organize workers along craft or industrial lines. Following passage of the law, Lewis began a widespread publicity campaign urging industrial workers to join “the president’s union.” The relationship was mutually beneficial to Roosevelt, who subsequently received the endorsement of Lewis’s United Mine Workers union in the 1936 presidential election, along with a sizeable $500,000 campaign contribution. The Wagner Act permanently established government-secured workers’ rights and protections from their employers, and it marked the beginning of labor’s political support for the Democratic Party.
The various programs that made up the Second New Deal are listed in the table below ().
### THE FINAL PIECES
Roosevelt entered the 1936 presidential election on a wave of popularity, and he beat Republican opponent Alf Landon by a nearly unanimous Electoral College vote of 523 to 8. Believing it to be his moment of strongest public support, Roosevelt chose to exact a measure of revenge against the U.S. Supreme Court for challenging his programs and to pressure them against challenging his more recent Second New Deal provisions. To this end, Roosevelt created the informally named “Supreme Court Packing Plan” and tried to pack the court in his favor by expanding the number of justices and adding new ones who supported his views. His plan was to add one justice for every current justice over the age of seventy who refused to step down. This would have allowed him to add six more justices, expanding the bench from nine to fifteen. Opposition was quick and thorough from both the Supreme Court and Congress, as well as from his own party. The subsequent retirement of Justice Van Devanter from the court, as well as the sudden death of Senator Joe T. Robinson, who championed Roosevelt’s plan before the Senate, all but signaled Roosevelt’s defeat. However, although he never received the support to make these changes, Roosevelt appeared to succeed in politically intimidating the current justices into supporting his newer programs, and they upheld both the Wagner Act and the Social Security Act. Never again during his presidency would the Supreme Court strike down any significant elements of his New Deal.
Roosevelt was not as successful in addressing the nation’s growing deficit. When he entered the presidency in 1933, Roosevelt did so with traditionally held fiscal beliefs, including the importance of a balanced budget in order to maintain public confidence in federal government operations. However, the severe economic conditions of the depression quickly convinced the president of the importance of government spending to create jobs and relief for the American people. As he commented to a crowd in Pittsburgh in 1936, “To balance our budget in 1933 or 1934 or 1935 would have been a crime against the American people. To do so . . . we should have had to set our face against human suffering with callous indifference. When Americans suffered, we refused to pass by on the other side. Humanity came first.” However, after his successful re-election, Roosevelt anticipated that the economy would recover enough by late 1936 that he could curtail spending by 1937. This reduction in spending, he hoped, would curb the deficit. As the early months of 1937 unfolded, Roosevelt’s hopes seemed supported by the most recent economic snapshot of the country. Production, wages, and profits had all returned to pre-1929 levels, while unemployment was at its lowest rate in the decade, down from 25 percent to 14 percent. But no sooner did Roosevelt cut spending when a recession hit. Two million Americans were newly out of work as unemployment quickly rose by 5 percent and industrial production declined by a third. Breadlines began to build again, while banks prepared to close.
Historians continue to debate the causes of this recession within a depression. Some believe the fear of increased taxes forced factory owners to curtail planned expansion; others blame the Federal Reserve for tightening the nation’s money supply. Roosevelt, however, blamed the downturn on his decision to significantly curtail federal government spending in job relief programs such as the WPA. Several of his closest advisors, including Harry Hopkins, Henry Wallace, and others, urged him to adopt the new economic theory espoused by British economic John Maynard Keynes, who argued that deficit spending was necessary in advanced capitalist economies in order to maintain employment and stimulate consumer spending. Convinced of the necessity of such an approach, Roosevelt asked Congress in the spring of 1938 for additional emergency relief spending. Congress immediately authorized $33 billion for PWA and WPA work projects. Although World War II would provide the final impetus for lasting economic recovery, Roosevelt’s willingness to adapt in 1938 avoided another disaster.
Roosevelt signed the last substantial piece of New Deal legislation in the summer of 1938. The Fair Labor Standards Act established a federal minimum wage—at the time, forty-five-cents per hour—a maximum workweek of forty hours (with an opportunity for four additional hours of work at overtime wages), and prohibited child labor for those under age sixteen. Roosevelt was unaware that the war would soon dominate his legacy, but this proved to be his last major piece of economic legislation in a presidency that changed the fabric of the country forever.
### IN THE FINAL ANALYSIS
The legacy of the New Deal is in part seen in the vast increase in national power: The federal government accepted responsibility for the nation’s economic stability and prosperity. In retrospect, the majority of historians and economists judge it to have been a tremendous success. The New Deal not only established minimum standards for wages, working conditions, and overall welfare, it also allowed millions of Americans to hold onto their homes, farms, and savings. It laid the groundwork for an agenda of expanded federal government influence over the economy that continued through President Harry Truman’s “Fair Deal” in the 1950s and President Lyndon Johnson’s call for a “Great Society” in the 1960s. The New Deal state that embraced its responsibility for the citizens’ welfare and proved willing to use its power and resources to spread the nation’s prosperity lasted well into the 1980s, and many of its tenets persist today. Many would also agree that the postwar economic stability of the 1950s found its roots in the stabilizing influences introduced by social security, the job stability that union contracts provided, and federal housing mortgage programs introduced in the New Deal. The environment of the American West in particular, benefited from New Deal projects such as the Soil Conservation program.
Still, Roosevelt’s programs also had their critics. Following the conservative rise initiated by presidential candidate Barry Goldwater in 1964, and most often associated with the Ronald Reagan era of the 1980s, critics of the welfare state pointed to Roosevelt’s presidency as the start of a slippery slope towards entitlement and the destruction of the individualist spirit upon which the United States had presumably developed in the nineteenth and early twentieth centuries. Although the growth of the GDP between 1934 and 1940 approached an average of 7.5 percent—higher than in any other peacetime period in U.S. history, critics of the New Deal point out that unemployment still hovered around 15 percent in 1940. While the New Deal resulted in some environmental improvements, it also inaugurated a number of massive infrastructural projects, such as the Grand Coulee Dam on the Columbia River, that came with grave environmental consequences. And other shortcomings of the New Deal were obvious and deliberate at the time.
### African Americans under the New Deal
Critics point out that not all Americans benefited from the New Deal. African Americans in particular were left out, with overt discrimination in hiring practices within the federal job programs, such as the CCC, CWA, and WPA. The NRA was oftentimes criticized as the “Negro Run Around” or “Negroes Ruined Again” program. As well, the AAA left tenant farmers and sharecroppers, many of whom were Black, with no support. Even Social Security originally excluded domestic workers, a primary source of employment for African American women. Facing such criticism early in his administration, Roosevelt undertook some efforts to ensure a measure of equality in hiring practices for the relief agencies, and opportunities began to present themselves by 1935. The WPA eventually employed 350,000 African Americans annually, accounting for nearly 15 percent of its workforce. By the close of the CCC in 1938, this program had employed over 300,000 African Americans, increasing the Black percentage of its workforce from 3 percent at the outset to nearly 11 percent at its close. Likewise, in 1934, the PWA began to require that all government projects under its purview hire African Americans using a quota that reflected their percentage of the local population being served. Additionally, among several important WPA projects, Federal Project Number One included a literacy program that eventually reached over one million African American children, helping them learn how to read and write.
On the issue of race relations themselves, Roosevelt has a mixed legacy. Within his White House, Roosevelt had a number of African American appointees, although most were in minor positions. Unofficially, Roosevelt relied upon advice from the Federal Council on Negro Affairs, also known as his “Black Cabinet.” This group included a young Harvard economist, Dr. Robert Weaver, who subsequently became the nation’s first Black cabinet secretary in 1966, as President Lyndon Johnson’s Secretary of Housing and Urban Development. Aubrey Williams, the director of the NYA, hired more Black administrators than any other federal agency, and appointed them to oversee projects throughout the country. One key figure in the NYA was Mary McLeod Bethune (), a prominent African American educator tapped by Roosevelt to act as the director of the NYA’s Division of Negro Affairs. Bethune had been a spokesperson and an educator for years; with this role, she became one of the president’s foremost African American advisors. During his presidency, Roosevelt became the first to appoint a Black federal judge, as well as the first commander-in-chief to promote an African American to brigadier general. Most notably, he became the first president to publicly speak against lynching as a “vile form of collective murder.”
However, despite these efforts, Roosevelt also understood the precariousness of his political position. In order to maintain a coalition of Democrats to support his larger relief and recovery efforts, Roosevelt could not afford to alienate Southern Democrats who might easily bolt should he openly advocate for civil rights. While he spoke about the importance of anti-lynching legislation, he never formally pushed Congress to propose such a law. He did publicly support the abolition of the poll tax, which Congress eventually accomplished in 1941. Likewise, although agency directors adopted changes to ensure job opportunities for African Americans at the federal level, at the local level, few advancements were made, and African Americans remained at the back of the employment lines. Despite such failures, however, Roosevelt deserves credit for acknowledging the importance of race relations and civil rights. At the federal level, more than any of his predecessors since the Civil War, Roosevelt remained aware of the role that the federal government can play in initiating important discussions about civil rights, as well as encouraging the development of a new cadre of civil rights leaders.
Although unable to bring about sweeping civil rights reforms for African Americans in the early stages of his administration, Roosevelt was able to work with Congress to significantly improve the lives of Native Americans. In 1934, he signed into law the Indian Reorganization Act (sometimes referred to as the “Indian New Deal”). This law formally abandoned the assimilationist policies set forth in the Dawes Severalty Act of 1887. Rather than forcing Native Americans to adapt to American culture, the new program encouraged them to develop forms of local self-government, as well as to preserve their artifacts and heritage. John Collier, the Commissioner on Indian Bureau Affairs from 1933 to 1945, championed this legislation and saw it as an opportunity to correct past injustices that land allotment and assimilation had wrought upon Native peoples. Although the re-establishment of communal tribal lands would prove to be difficult, Collier used this law to convince federal officials to return nearly two million acres of government-held land to various tribes in order to move the process along. Although subsequent legislation later circumscribed the degree to which tribes were allowed to self-govern on reservations, Collier’s work is still viewed as a significant step in improving race relations with Native Americans and preserving their heritage.
### Women and the New Deal
For women, Roosevelt’s policies and practices had a similarly mixed effect. Wage discrimination in federal jobs programs was rampant, and relief policies encouraged women to remain home and leave jobs open for men. This belief was well in line with the gender norms of the day. Several federal relief programs specifically forbade husbands and wives’ both drawing jobs or relief from the same agency. The WPA became the first specific New Deal agency to openly hire women—specifically widows, single women, and the wives of disabled husbands. While they did not take part in construction projects, these women did undertake sewing projects to provide blankets and clothing to hospitals and relief agencies. Likewise, several women took part in the various Federal One art projects. Despite the obvious gender limitations, many women strongly supported Roosevelt’s New Deal, as much for its direct relief handouts for women as for its employment opportunities for men. One such woman was Mary (Molly) Dewson. A longtime activist in the women’s suffrage movement, Dewson worked for women’s rights and ultimately rose to be the Director of the Women’s Division of the Democratic Party. Dewson and Mary McLeod Bethune, the national champion of African American education and literacy who rose to the level of Director of the Division of Negro Affairs for the NYA, understood the limitations of the New Deal, but also the opportunities for advancement it presented during very trying times. Rather than lamenting what Roosevelt could not or would not do, they felt, and perhaps rightly so, that Roosevelt would do more than most to help women and African Americans achieve a piece of the new America he was building.
Among the few, but notable, women who directly impacted Roosevelt’s policies was Frances Perkins, who as Secretary of Labor was the first female member of any presidential cabinet, and First Lady Eleanor Roosevelt, who was a strong and public advocate for social causes. Perkins, one of only two original Cabinet members to stay with Roosevelt for his entire presidency, was directly involved in the administration of the CCC, PWA, NRA, and the Social Security Act. Among several important measures, she took greatest pleasure in championing minimum wage statutes as well as the penultimate piece of New Deal legislation, the Fair Labor Standards Act. Roosevelt came to trust Perkins’ advice with few questions or concerns, and steadfastly supported her work through the end of his life (Figure 26_03_Perkins).
However, Eleanor Roosevelt, more so than any other individual, came to represent the strongest influence upon the president; and she used her unique position to champion several causes for women, African Americans, and the rural poor (). She married Franklin Roosevelt, who was her fifth cousin, in 1905 and subsequently had six children, one of whom died at only seven months old. A strong supporter of her husband’s political ambitions, Eleanor campaigned by his side through the failed vice-presidential bid in 1920 and on his behalf after he was diagnosed with polio in 1921. When she discovered letters of her husband’s affair with her social secretary, Lucy Mercer, the marriage became less one of romance and more one of a political partnership that would continue—strained at times—until the president’s death in 1945.
Historians agree that the first lady used her presence in the White House, in addition to the leverage of her failed marriage and knowledge of her husband’s infidelities, to her advantage. She promoted several causes that the president himself would have had difficulty championing at the time. From newspaper and magazine articles she authored, to a busy travel schedule that saw her regularly cross the country, the first lady sought to remind Americans that their plight was foremost on the minds of all working in the White House. Eleanor was so active in her public appearances that, by 1940, she began holding regular press conferences to answer reporters’ questions. Among her first substantial projects was the creation of Arthurdale—a resettlement community for displaced coal miners in West Virginia. Although the planned community became less of an administration priority as the years progressed (eventually folding in 1940), for seven years, Eleanor remained committed to its success as a model of assistance for the rural poor.
Exposed to issues of racial segregation in the Arthurdale experiment, Eleanor subsequently supported many civil rights causes through the remainder of the Roosevelt presidency. When it further became clear that racial discrimination was rampant in the administration of virtually all New Deal job programs—especially in the southern states—she continued to pressure her husband for remedies. In 1934, she openly lobbied for passage of the federal anti-lynching bill that the president privately supported but could not politically endorse. Despite the subsequent failure of the Senate to pass such legislation, Eleanor succeeded in arranging a meeting between her husband and then-NAACP president Walter White to discuss anti-lynching and other pertinent calls for civil rights legislation.
White was only one of Eleanor’s African American guests to the White House. Breaking with precedent, and much to the disdain of many White House officials, the first lady routinely invited prominent African Americans to dine with her and the president. Most notably, when the Daughters of the American Revolution (DAR) refused to permit internationally renowned Black opera contralto Marian Anderson to sing in Constitution Hall, Eleanor resigned her membership in the DAR and arranged for Anderson to sing at a public concert on the steps of the Lincoln Memorial, followed by her appearance at a state dinner at the White House in honor of the king and queen of England. With regard to race relations in particular, Eleanor Roosevelt was able to accomplish what her husband—for delicate political reasons—could not: become the administration’s face for civil rights.
### Section Summary
Despite his popularity, Roosevelt had significant critics at the end of the First New Deal. Some on the right felt that he had moved the country in a dangerous direction towards socialism and fascism, whereas others on the left felt that he had not gone far enough to help the still-struggling American people. Reeling after the Supreme Court struck down two key pieces of New Deal legislation, the AAA and NIRA, Roosevelt pushed Congress to pass a new wave of bills to provide jobs, banking reforms, and a social safety net. The laws that emerged—the Banking Act, the Emergency Relief Appropriation Act, and the Social Security Act—still define our country today.
Roosevelt won his second term in a landslide and continued to push for legislation that would help the economy. The jobs programs employed over eight million people and, while systematic discrimination hurt both women and African American workers, these programs were still successful in getting people back to work. The last major piece of New Deal legislation that Roosevelt passed was the Fair Labor Standards Act, which set a minimum wage, established a maximum-hour workweek, and forbade child labor. This law, as well as Social Security, still provides much of the social safety net in the United States today.
While critics and historians continue to debate whether the New Deal ushered in a permanent change to the political culture of the country, from one of individualism to the creation of a welfare state, none deny the fact that Roosevelt’s presidency expanded the role of the federal government in all people’s lives, generally for the better. Even if the most conservative of presidential successors would question this commitment, the notion of some level of government involvement in economic regulation and social welfare had largely been settled by 1941. Future debates would be about the extent and degree of that involvement.
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### Critical Thinking Questions
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# Fighting the Good Fight in World War II, 1941-1945
## Introduction
World War II awakened the sleeping giant of the United States from the lingering effects of the Great Depression. Although the country had not entirely disengaged itself from foreign affairs following World War I, it had remained largely divorced from events occurring in Europe until the late 1930s. World War II forced the United States to involve itself once again in European affairs. It also helped to relieve the unemployment of the 1930s and stir industrial growth. The propaganda poster above () was part of a concerted effort to get Americans to see themselves as citizens of a strong, unified country, dedicated to the protection of freedom and democracy. However, the war that unified many Americans also brought to the fore many of the nation’s racial and ethnic divisions, both on the frontlines—where military units, such as the one depicted in this poster, were segregated by race—and on the home front. Yet, the war also created new opportunities for ethnic minorities and women, which, in postwar America, would contribute to their demand for greater rights. |
# Fighting the Good Fight in World War II, 1941-1945
## The Origins of War: Europe, Asia, and the United States
The years between the First and Second World Wars were politically and economically tumultuous for the United States and especially for the world. The Russian Revolution of 1917, Germany’s defeat in World War I, and the subsequent Treaty of Versailles had broken up the Austro-Hungarian, German, and Russian empires and significantly redrew the map of Europe. President Woodrow Wilson had wished to make World War I the “war to end all wars” and hoped that his new paradigm of “collective security” in international relations, as actualized through the League of Nations, would limit power struggles among the nations of the world. However, during the next two decades, America’s attention turned away from global politics and toward its own needs. At the same time, much of the world was dealing with economic and political crises, and different types of totalitarian regimes began to take hold in Europe. In Asia, an ascendant Japan began to expand its borders. Although the United States remained focused on the economic challenges of the Great Depression as World War II approached, ultimately it became clear that American involvement in the fight against Nazi Germany and Japan was in the nation’s interest.
### ISOLATION
While during the 1920s and 1930s there were Americans who favored active engagement in Europe, most Americans, including many prominent politicians, were leery of getting too involved in European affairs or accepting commitments to other nations that might restrict America’s ability to act independently, keeping with the isolationist tradition. Although the United States continued to intervene in the affairs of countries in the Western Hemisphere during this period, the general mood in America was to avoid becoming involved in any crises that might lead the nation into another global conflict.
Despite its largely noninterventionist foreign policy, the United States did nevertheless take steps to try to lessen the chances of war and cut its defense spending at the same time. President Warren G. Harding’s administration participated in the Washington Naval Conference of 1921–1922, which reduced the size of the navies of the nine signatory nations. In addition, the Four Power Treaty, signed by the United States, Great Britain, France, and Japan in 1921, committed the signatories to eschewing any territorial expansion in Asia. In 1928, the United States and fourteen other nations signed the Kellogg-Briand Pact, declaring war an international crime. Despite hopes that such agreements would lead to a more peaceful world—far more nations signed on to the agreement in later years—they failed because none of them committed any of the nations to take action in the event of treaty violations.
### THE MARCH TOWARD WAR
While the United States focused on domestic issues, economic depression and political instability were growing in Europe. During the 1920s, the international financial system was propped up largely by American loans to foreign countries. The crash of 1929, when the U.S. stock market plummeted and American capital dried up, set in motion a series of financial chain reactions that contributed significantly to a global downward economic spiral. Around the world, industrialized economies faced significant problems of economic depression and worker unemployment.
### Totalitarianism in Europe
Many European countries had been suffering even before the Great Depression began. A postwar recession and the continuation of wartime inflation had hurt many economies, as did a decrease in agricultural prices, which made it harder for farmers to buy manufactured goods or pay off loans to banks. In such an unstable environment, Benito Mussolini capitalized on the frustrations of the Italian people who felt betrayed by the Versailles Treaty. In 1919, Mussolini created the Fasci Italiani di Combattimento (Italian Combat Squadron). The organization’s main tenets of Fascism called for a heightened focus on national unity, militarism, social Darwinism, and loyalty to the state. Mussolini wanted a state organized to be what he called totalitario (totalitarian), which he insisted would mean “all within the state, none outside the state, none against the state." With the support of major Italian industrialists and the king, who saw Fascism as a bulwark against growing Socialist and Communist movements, Mussolini became prime minister in 1922. Between 1925 and 1927, Mussolini transformed the nation into a single party state and removed all restraints on his power.
In Germany, a similar pattern led to the rise of the totalitarian National Socialist Party. Political fragmentation through the 1920s accentuated the severe economic problems facing the country. As a result, the German Communist Party began to grow in strength, frightening many wealthy and middle-class Germans. In addition, the terms of the Treaty of Versailles had given rise to a deep-seated resentment of the victorious Allies. It was in such an environment that Adolf Hitler’s anti-Communist National Socialist Party—the Nazis—was born.
The Nazis gained numerous followers during the Great Depression, which hurt Germany tremendously, plunging it further into economic crisis. By 1932, nearly 30 percent of the German labor force was unemployed. Not surprisingly, the political mood was angry and sullen. Hitler, a World War I veteran, promised to return Germany to greatness. By the beginning of 1933, the Nazis had become the largest party in the German legislature. Germany’s president, Paul von Hindenburg, at the urging of large industrialists who feared a Communist uprising, appointed Hitler to the position of chancellor in January 1933. In the elections that took place in early March 1933, the Nazis gained the political power to pass the Enabling Act later that same month, which gave Hitler the power to make all laws for the next four years. Hitler thus effectively became the dictator of Germany and remained so long after the four-year term passed. Like Italy, Germany had become a one-party totalitarian state (). Nazi Germany was an anti-Semitic nation, and in 1935, the Nuremberg Laws deprived Jews, whom Hitler blamed for Germany’s downfall, of German citizenship and the rights thereof.
Once in power, Hitler began to rebuild German military might. He commenced his program by withdrawing Germany from the League of Nations in October 1933. In 1936, in accordance with his promise to restore German greatness, Hitler dispatched military units into the Rhineland, on the border with France, which was an act contrary to the provisions of the Versailles Treaty. In March 1938, claiming that he sought only to reunite ethnic Germans within the borders of one country, Hitler invaded Austria. At a conference in Munich later that year, Great Britain’s prime minister, Neville Chamberlain, and France’s prime minister, Édouard Daladier, agreed to the partial dismemberment of Czechoslovakia and the occupation of the Sudetenland (a region with a sizable German population) by German troops (). This Munich Pact offered a policy of appeasement, in the hope that German expansionist appetites could be satisfied without war. But not long after the agreement, Germany occupied the rest of Czechoslovakia as well.
Leaders in the Soviet Union, which developed its own form of brutal totalitarianism through communism, paid close attention to Hitler’s actions and public pronouncements. Soviet leader Joseph Stalin realized that Poland, part of which had belonged to Germany before the First World War, was most likely next. Although fiercely opposed to Hitler, Stalin, sobered by the French and British betrayal of Czechoslovakia and unprepared for a major war, decided the best way to protect the Soviet Union, and gain additional territory, was to come to some accommodation with the German dictator. In August 1939, Germany and the Soviet Union essentially agreed to divide Poland between them and not make war upon one another.
### Japan
Militaristic politicians also took control of Japan in the 1930s. The Japanese had worked assiduously for decades to modernize, build their strength, and become a prosperous, respected nation. The sentiment in Japan was decidedly pro-capitalist, and the Japanese militarists were fiercely supportive of a capitalist economy. They viewed with great concern the rise of Communism in the Soviet Union and in particular China, where the issue was fueling a civil war, and feared that the Soviet Union would make inroads in Asia by assisting China’s Communists. The Japanese militarists thus found a common ideological enemy with Fascism and National Socialism, which had based their rise to power on anti-Communist sentiments. In 1936, Japan and Germany signed the Anti-Comintern Pact, pledging mutual assistance in defending themselves against the Comintern, the international agency created by the Soviet Union to promote worldwide Communist revolution. In 1937, Italy joined the pact, essentially creating the foundation of what became the military alliance of the Axis powers.
Like its European allies, Japan was intent upon creating an empire for itself. In 1931, it created a new nation, a puppet state called Manchukuo, which had been cobbled together from the three northernmost provinces of China. Although the League of Nations formally protested Japan’s seizure of Chinese territory in 1931 and 1932, it did nothing else. In 1937, a clash between Japanese and Chinese troops, known as the Marco Polo Bridge Incident, led to a full-scale invasion of China by the Japanese. By the end of the year, the Chinese had suffered some serious defeats. In Nanjing, then called Nanking by Westerners, Japanese soldiers systematically raped Chinese women and massacred hundreds of thousands of civilians, leading to international outcry. Public sentiment against Japan in the United States reached new heights. Members of Protestant churches that were involved in missionary work in China were particularly outraged, as were Chinese Americans. A troop of Chinese American Boy Scouts in New York City’s Chinatown defied Boy Scout policy and marched in protest against Japanese aggression.
### FROM NEUTRALITY TO ENGAGEMENT
President Franklin Roosevelt was aware of the challenges facing the targets of Nazi aggression in Europe and Japanese aggression in Asia. Although he hoped to offer U.S. support, Congress’s commitment to nonintervention was difficult to overcome. Such a policy in regards to Europe was strongly encouraged by Senator Gerald P. Nye of North Dakota. Nye claimed that the United States had been tricked into participating in World War I by a group of industrialists and bankers who sought to gain from the country’s participation in the war. The United States, Nye urged, should not be drawn again into an international dispute over matters that did not concern it. His sentiments were shared by other noninterventionists in Congress ().
Roosevelt’s willingness to accede to the demands of the noninterventionists led him even to refuse assistance to those fleeing Nazi Germany. Although Roosevelt was aware of Nazi persecution of the Jews, he did little to aid them. In a symbolic act of support, he withdrew the American ambassador to Germany in 1938. He did not press for a relaxation of immigration quotas that would have allowed more refugees to enter the country, however. In 1939, he refused to support a bill that would have admitted twenty thousand Jewish refugee children to the United States. Again in 1939, when German refugees aboard the SS St. Louis, most of them Jews, were refused permission to land in Cuba and turned to the United States for help, the U.S. State Department informed them that immigration quotas for Germany had already been filled. Once again, Roosevelt did not intervene, because he feared that nativists in Congress might smear him as a friend of Jews.
To ensure that the United States did not get drawn into another war, Congress passed a series of Neutrality Acts in the second half of the 1930s. The Neutrality Act of 1935 banned the sale of armaments to warring nations. The following year, another Neutrality Act prohibited loaning money to belligerent countries. The last piece of legislation, the Neutrality Act of 1937, forbade the transportation of weapons or passengers to belligerent nations on board American ships and also prohibited American citizens from traveling on board the ships of nations at war.
Once all-out war began between Japan and China in 1937, Roosevelt sought ways to help the Chinese that did not violate U.S. law. Since Japan did not formally declare war on China, a state of belligerency did not technically exist. Therefore, under the terms of the Neutrality Acts, America was not prevented from transporting goods to China. In 1940, the president of China, Chiang Kai-shek, was able to prevail upon Roosevelt to ship to China one hundred P-40 fighter planes and to allow American volunteers, who technically became members of the Chinese Air Force, to fly them.
### War Begins in Europe
In 1938, the agreement reached at the Munich Conference failed to satisfy Hitler—in fact, the refusal of Britain and France to go to war over the issue infuriated the German dictator. In May of the next year, Germany and Italy formalized their military alliance with the “Pact of Steel.” On September 1, 1939, Hitler unleashed his Blitzkrieg, or “lightning war,” against Poland, using swift, surprise attacks combining infantry, tanks, and aircraft to quickly overwhelm the enemy. Britain and France had already learned from Munich that Hitler could not be trusted and that his territorial demands were insatiable. On September 3, 1939, they declared war on Germany, and the European phase of World War II began. Responding to the German invasion of Poland, Roosevelt worked with Congress to alter the Neutrality Laws to permit a policy of “Cash and Carry” in munitions for Britain and France. The legislation, passed and signed by Roosevelt in November 1939, permitted belligerents to purchase war materiel if they could pay cash for it and arrange for its transportation on board their own ships.
When the Germans commenced their spring offensive in 1940, they defeated France in six weeks with a highly mobile and quick invasion of France, Belgium, Luxembourg, and the Netherlands. In the Far East, Japan took advantage of France’s surrender to Germany to occupy French Indochina. In response, beginning with the Export Control Act in July 1940, the United States began to embargo the shipment of various materials to Japan, starting first with aviation gasoline and machine tools, and proceeding to scrap iron and steel.
### The Atlantic Charter
Following the surrender of France, the Battle of Britain began, as Germany proceeded to try to bomb England into submission. As the battle raged in the skies over Great Britain throughout the summer and autumn of 1940 (), Roosevelt became increasingly concerned over England’s ability to hold out against the German juggernaut. In June 1941, Hitler broke the nonaggression pact with the Soviet Union that had given him the backing to ravage Poland and marched his armies deep into Soviet territory, where they would kill Red Army regulars and civilians by the millions until their advances were stalled and ultimately reversed by the devastating battle of Stalingrad, which took place from August 23, 1942 until February 2, 1943 when, surrounded and out of ammunition, the German 6th army surrendered.
In August 1941, Roosevelt met with the British prime minister, Winston Churchill, off the coast of Newfoundland, Canada. At this meeting, the two leaders drafted the Atlantic Charter, the blueprint of Anglo-American cooperation during World War II. The charter stated that the United States and Britain sought no territory from the conflict. It proclaimed that citizens of all countries should be given the right of self-determination, self-government should be restored in places where it had been eliminated, and trade barriers should be lowered. Further, the charter mandated freedom of the seas, renounced the use of force to settle international disputes, and called for postwar disarmament.
In March 1941, concerns over Britain’s ability to defend itself also influenced Congress to authorize a policy of Lend Lease, a practice by which the United States could sell, lease, or transfer armaments to any nation deemed important to the defense of the United States. Lend Lease effectively ended the policy of nonintervention and dissolved America’s pretense of being a neutral nation. The program ran from 1941 to 1945, and distributed some $45 billion worth of weaponry and supplies to Britain, the Soviet Union, China, and other allies.
### A Date Which Will Live in Infamy
By the second half of 1941, Japan was feeling the pressure of the American embargo. As it could no longer buy strategic material from the United States, the Japanese were determined to obtain a sufficient supply of oil by taking control of the Dutch East Indies. However, they realized that such an action might increase the possibility of American intervention, since the Philippines, a U.S. territory, lay on the direct route that oil tankers would have to take to reach Japan from Indonesia. Japanese leaders thus attempted to secure a diplomatic solution by negotiating with the United States while also authorizing the navy to plan for war. The Japanese government also decided that if no peaceful resolution could be reached by the end of November 1941, then the nation would have to go to war against the United States.
The American final counterproposal to various offers by Japan was for the Japanese to completely withdraw, without any conditions, from China and enter into nonaggression pacts with all the Pacific powers. Japan found that proposal unacceptable but delayed its rejection for as long as possible. Then, at 7:48 a.m. on Sunday, December 7, the Japanese attacked the U.S. Pacific fleet at anchor in Pearl Harbor, Hawaii (). They launched two waves of attacks from six aircraft carriers that had snuck into the central Pacific without being detected. The attacks brought some 353 fighters, bombers, and torpedo bombers down on the unprepared fleet. The Japanese hit all eight battleships in the harbor and sank four of them. They also damaged several cruisers and destroyers. On the ground, nearly two hundred aircraft were destroyed, and twenty-four hundred servicemen were killed. Another eleven hundred were wounded. Japanese losses were minimal. The strike was part of a more concerted campaign by the Japanese to gain territory. They subsequently attacked Hong Kong, Malaysia, Singapore, Guam, Wake Island, and the Philippines.
Whatever reluctance to engage in conflict the American people had had before December 7, 1941, quickly evaporated. Americans’ incredulity that Japan would take such a radical step quickly turned to a fiery anger, especially as the attack took place while Japanese diplomats in Washington were still negotiating a possible settlement. President Roosevelt, referring to the day of the attack as “a date which will live in infamy,” asked Congress for a declaration of war, which it delivered to Japan on December 8. On December 11, Germany and Italy declared war on the United States in accordance with their alliance with Japan. Against its wishes, the United States had become part of the European conflict.
### Section Summary
America sought, at the end of the First World War, to create new international relationships that would make such wars impossible in the future. But as the Great Depression hit Europe, several new leaders rose to power under the new political ideologies of Fascism and Nazism. Mussolini in Italy and Hitler in Germany were both proponents of Fascism, using dictatorial rule to achieve national unity. Still, the United States remained focused on the economic challenges of its own Great Depression. Hence, there was little interest in getting involved in Europe’s problems or even the China-Japan conflict.
It soon became clear, however, that Germany and Italy’s alliance was putting democratic countries at risk. Roosevelt first sought to support Great Britain and China by providing economic support without intervening directly. However, when Japan, an ally of Germany and Italy, attacked Pearl Harbor, catching the military base unaware and claiming thousands of lives, America’s feelings toward war shifted, and the country was quickly pulled into the global conflict.
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# Fighting the Good Fight in World War II, 1941-1945
## The Home Front
The impact of the war on the United States was nowhere near as devastating as it was in Europe and the Pacific, where the battles were waged, but it still profoundly changed everyday life for all Americans. On the positive side, the war effort finally and definitively ended the economic depression that had been plaguing the country since 1929. It also called upon Americans to unite behind the war effort and give of their money, their time, and their effort, as they sacrificed at home to assure success abroad. The upheaval caused by White men leaving for war meant that for many disenfranchised groups, such as women and African Americans, there were new opportunities in employment and wage earning. Still, fear and racism drove cracks in the nation’s unified facade.
### MOBILIZING A NATION
Although the United States had sought to avoid armed conflict, the country was not entirely unprepared for war. Production of armaments had increased since 1939, when, as a result of Congress’s authorization of the Cash and Carry policy, contracts for weapons had begun to trickle into American factories. War production increased further following the passage of Lend Lease in 1941. However, when the United States entered the war, the majority of American factories were still engaged in civilian production, and many doubted that American businesses would be sufficiently motivated to convert their factories to wartime production.
Just a few years earlier, Roosevelt had been frustrated and impatient with business leaders when they failed to fully support the New Deal, but enlisting industrialists in the nation’s crusade was necessary if the United States was to produce enough armaments to win the war. To encourage cooperation, the government agreed to assume all costs of development and production, and also guarantee a profit on the sale of what was produced. This arrangement resulted in 233 to 350 percent increases in profits over what the same businesses had been able to achieve from 1937 to 1940. In terms of dollars earned, corporate profits rose from $6.4 billion in 1940 to nearly $11 billion in 1944. As the country switched to wartime production, the top one hundred U.S. corporations received approximately 70 percent of government contracts; big businesses prospered.
In addition to gearing up industry to fight the war, the country also needed to build an army. A peacetime draft, the first in American history, had been established in September 1940, but the initial draftees were to serve for only one year, a length of time that was later extended. Furthermore, Congress had specified that no more than 900,000 men could receive military training at any one time. By December 1941, the United States had only one division completely ready to be deployed. Military planners estimated that it might take nine million men to secure victory. A massive draft program was required to expand the nation’s military forces. Over the course of the war, approximately fifty million men registered for the draft; ten million were subsequently inducted into the service.
Approximately 2.5 million African Americans registered for the draft, and 1 million of them subsequently served. Initially, African American soldiers, who served in segregated units, had been used as support troops and not been sent into combat. By the end of the war, however, manpower needs resulted in African American recruits serving in the infantry and flying planes. The Tuskegee Institute in Alabama had instituted a civilian pilot training program for aspiring African American pilots. When the war began, the Department of War absorbed the program and adapted it to train combat pilots. First Lady Eleanor Roosevelt demonstrated both her commitment to African Americans and the war effort by visiting Tuskegee in 1941, shortly after the unit had been organized. To encourage the military to give the airmen a chance to serve in actual combat, she insisted on taking a ride in a plane flown by an African American pilot to demonstrate the Tuskegee Airmen’s skill (). When the Tuskegee Airmen did get their opportunity to serve in combat, they did so with distinction.
In addition, forty-four thousand Native Americans served in all theaters of the war. In some of the Pacific campaigns, Native Americans made distinct and unique contributions to Allied victories. Navajo marines served in communications units, exchanging information over radios using codes based on their native language, which the Japanese were unable to comprehend or to crack. They became known as code talkers and participated in the battles of Guadalcanal, Iwo Jima, Peleliu, and Tarawa. A smaller number of Comanche code talkers performed a similar function in the European theater.
While millions of Americans heeded the rallying cry for patriotism and service, there were those who, for various reasons, did not accept the call. Before the war began, American Peace Mobilization had campaigned against American involvement in the European conflict as had the noninterventionist America First organization. Both groups ended their opposition, however, at the time of the German invasion of the Soviet Union and the Japanese attack on Pearl Harbor, respectively. Nevertheless, during the war, some seventy-two thousand men registered as conscientious objectors (COs), and fifty-two thousand were granted that status. Of that fifty-two thousand, some accepted noncombat roles in the military, whereas others accepted unpaid work in civilian work camps. Many belonged to pacifist religious sects such as the Quakers or Mennonites. They were willing to serve their country, but they refused to kill. COs suffered public condemnation for disloyalty, and family members often turned against them. Strangers assaulted them. A portion of the town of Plymouth, NH, was destroyed by fire because the residents did not want to call upon the services of the COs trained as firemen at a nearby camp. Only a very small number of men evaded the draft completely.
Most Americans, however, were willing to serve, and they required a competent officer corps. The very same day that Germany invaded Poland in 1939, President Roosevelt promoted George C. Marshall, a veteran of World War I and an expert at training officers, from a one-star general to a four-star general, and gave him the responsibility of serving as Army Chief of Staff. The desire to create a command staff that could win the army’s confidence no doubt contributed to the rather meteoric rise of Dwight D. Eisenhower (). During World War I, Eisenhower had been assigned to organize America’s new tank corps, and, although he never saw combat during the war, he demonstrated excellent organizational skills. When the United States entered World War II, Eisenhower was appointed commander of the General European Theater of Operations in June 1942.
### EMPLOYMENT AND MIGRATION PATTERNS IN THE UNITED STATES
Even before the official beginning of the war, the country started to prepare. In August 1940, Congress created the Defense Plant Corporation, which had built 344 plants in the West by 1945, and had funneled over $1.8 billion into the economies of western states. After Pearl Harbor, as American military strategists began to plan counterattacks and campaigns against the Axis powers, California became a training ground. Troops trained there for tank warfare and amphibious assaults as well as desert campaigns—since the first assault against the Axis powers was planned for North Africa.
As thousands of Americans swarmed to the West Coast to take jobs in defense plants and shipyards, cities like Richmond, California, and nearby Oakland, expanded quickly. Richmond grew from a city of 20,000 people to 100,000 in only three years. Almost overnight, the population of California skyrocketed. African Americans moved out of the rural South into northern or West Coast cities to provide the muscle and skill to build the machines of war. Building on earlier waves of African American migration after the Civil War and during World War I, the demographics of the nation changed with the growing urbanization of the African American population. Women also relocated to either follow their husbands to military bases or take jobs in the defense industry, as the total mobilization of the national economy began to tap into previously underemployed populations.
Roosevelt and his administration already had experience in establishing government controls and taking the initiative in economic matters during the Depression. In April 1941, Roosevelt created the Office of Price Administration (OPA), and, once the United States entered the war, the OPA regulated prices and attempted to combat inflation. The OPA ultimately had the power to set ceiling prices for all goods, except agricultural commodities, and to ration a long list of items. During the war, major labor unions pledged not to strike in order to prevent disruptions in production; in return, the government encouraged businesses to recognize unions and promised to help workers bargain for better wages.
As in World War I, the government turned to bond drives to finance the war. Millions of Americans purchased more than $185 billion worth of war bonds. Children purchased Victory Stamps and exchanged full stamp booklets for bonds. The federal government also instituted the current tax-withholding system to ensure collection of taxes. Finally, the government once again urged Americans to plant victory gardens, using marketing campaigns and celebrities to promote the idea (). Americans responded eagerly, planting gardens in their backyards and vacant lots.
The federal government also instituted rationing to ensure that America’s fighting men were well fed. Civilians were issued ration booklets, books of coupons that enabled them to buy limited amounts of meat, coffee, butter, sugar, and other foods. Wartime cookbooks were produced, such as the Betty Crocker cookbook Your Share, telling housewives how to prepare tasty meals without scarce food items. Other items were rationed as well, including shoes, liquor, cigarettes, and gasoline. With a few exceptions, such as doctors, Americans were allowed to drive their automobiles only on certain days of the week. Most Americans complied with these regulations, but some illegally bought and sold rationed goods on the black market.
Civilians on the home front also recycled, conserved, and participated in scrap drives to collect items needed for the production of war materiel. Housewives saved cooking fats, needed to produce explosives. Children collected scrap metal, paper, rubber, silk, nylon, and old rags. Some children sacrificed beloved metal toys in order to “win the war.” Civilian volunteers, trained to recognize enemy aircraft, watched the skies along the coasts and on the borders.
### WOMEN IN THE WAR: ROSIE THE RIVETER AND BEYOND
As in the previous war, the gap in the labor force created by departing soldiers meant opportunities for women. In particular, World War II led many to take jobs in defense plants and factories around the country. For many women, these jobs provided unprecedented opportunities to move into occupations previously thought of as exclusive to men, especially the aircraft industry, where a majority of workers were composed of women by 1943. Most women in the labor force did not work in the defense industry, however. The majority took over other factory jobs that had been held by men. Many took positions in offices as well. As White women, many of whom had been in the workforce before the war, moved into these more highly paid positions, African American women, most of whom had previously been limited to domestic service, took over White women’s lower-paying positions in factories; some were also hired by defense plants, however. Although women often earned more money than ever before, it was still far less than men received for doing the same jobs. Nevertheless, many achieved a degree of financial self-reliance that was enticing. By 1944, as many as 33 percent of the women working in the defense industries were mothers and worked “double-day” shifts—one at the plant and one at home.
Still, there was some resistance to women going to work in such a male-dominated environment. In order to recruit women for factory jobs, the government created a propaganda campaign centered on a now-iconic figure known as Rosie the Riveter (). Rosie, who was a composite based on several real women, was most famously depicted by American illustrator Norman Rockwell. Rosie was tough yet feminine. To reassure men that the demands of war would not make women too masculine, some factories gave female employees lessons in how to apply makeup, and cosmetics were never rationed during the war. Elizabeth Arden even created a special red lipstick for use by women reservists in the Marine Corps.
Although many saw the entry of women into the workforce as a positive thing, they also acknowledged that working women, especially mothers, faced great challenges. To try to address the dual role of women as workers and mothers, Eleanor Roosevelt urged her husband to approve the first U.S. government childcare facilities under the Community Facilities Act of 1942. Eventually, seven centers, servicing 105,000 children, were built. The First Lady also urged industry leaders like Henry Kaiser to build model childcare facilities for their workers. Still, these efforts did not meet the full need for childcare for working mothers.
The lack of childcare facilities meant that many children had to fend for themselves after school, and some had to assume responsibility for housework and the care of younger siblings. Some mothers took younger children to work with them and left them locked in their cars during the workday. Police and social workers also reported an increase in juvenile delinquency during the war. New York City saw its average number of juvenile cases balloon from 9,500 in the prewar years to 11,200 during the war. In San Diego, delinquency rates for girls, including sexual misbehavior, shot up by 355 percent. It is unclear whether more juveniles were actually engaging in delinquent behavior; the police may simply have become more vigilant during wartime and arrested youngsters for activities that would have gone overlooked before the war. In any event, law enforcement and juvenile courts attributed the perceived increase to a lack of supervision by working mothers.
Tens of thousands of women served in the war effort more directly. Approximately 350,000 joined the military. They worked as nurses, drove trucks, repaired airplanes, and performed clerical work to free up men for combat. Over sixteen hundred of the women nurses received various decorations for courage under fire, but many also died or were captured in the war zones. Those who joined the Women’s Airforce Service Pilots (WASPs) flew planes from the factories to military bases. Many women also flocked to work in a variety of civil service jobs. Others worked as chemists and engineers, developing weapons for the war. This included thousands of women who were recruited to work on the Manhattan Project, developing the atomic bomb.
### THE CULTURE OF WAR: ENTERTAINERS AND THE WAR EFFORT
During the Great Depression, movies had served as a welcome diversion from the difficulties of everyday life, and during the war, this held still truer. By 1941, there were more movie theaters than banks in the United States. In the 1930s, newsreels, which were shown in movie theaters before feature films, had informed the American public of what was happening elsewhere in the world. This interest grew once American armies began to engage the enemy. Many informational documentaries about the war were also shown in movie theaters. The most famous were those in the Why We Fight series, filmed by Hollywood director Frank Capra. During the war, Americans flocked to the movies not only to learn what was happening to the troops overseas but also to be distracted from the fears and hardships of wartime by cartoons, dramas, and comedies. By 1945, movie attendance had reached an all-time high.
Many feature films were patriotic stories that showed the day’s biggest stars as soldiers fighting the nefarious German and Japanese enemy. During the war years, there was a consistent supply of patriotic movies, with actors glorifying and inspiring America’s fighting men. John Wayne, who had become a star in the 1930s, appeared in many war-themed movies, including The Fighting Seabees and Back to Bataan.
Besides appearing in patriotic movies, many male entertainers temporarily gave up their careers to serve in the armed forces (). Jimmy Stewart served in the Army Air Force and appeared in a short film entitled Winning Your Wings that encouraged young men to enlist. Tyrone Power joined the U.S. Marines. Female entertainers did their part as well. Rita Hayworth and Marlene Dietrich entertained the troops. African American singer and dancer Josephine Baker entertained Allied troops in North Africa and also carried secret messages for the French Resistance. Actress Carole Lombard was killed in a plane crash while returning home from a rally where she had sold war bonds.
### SOCIAL TENSIONS ON THE HOME FRONT
The need for Americans to come together, whether in Hollywood, the defense industries, or the military, to support the war effort encouraged feelings of unity among the American population. However, the desire for unity did not always mean that Americans of color were treated as equals or even tolerated, despite their proclamations of patriotism and their willingness to join in the effort to defeat America’s enemies in Europe and Asia. For African Americans, Mexican Americans, and especially for Japanese Americans, feelings of patriotism and willingness to serve one’s country both at home and abroad was not enough to guarantee equal treatment by White Americans or to prevent the U.S. government from regarding them as the enemy.
### African Americans and Double V
The African American community had, at the outset of the war, forged some promising relationships with the Roosevelt administration through civil rights activist Mary McLeod Bethune and Roosevelt’s “Black Cabinet” of African American advisors. Through the intervention of Eleanor Roosevelt, Bethune was appointed to the advisory council set up by the War Department Women’s Interest Section. In this position, Bethune was able to organize the first officer candidate school for women and enable African American women to become officers in the Women’s Army Auxiliary Corps (WAAC), which was renamed Women's Army Corps (WAC) a year later when it was authorized as a branch of the U.S. Army.
As the U.S. economy revived as a result of government defense contracts, African Americans wanted to ensure that their service to the country earned them better opportunities and more equal treatment. Accordingly, in 1941, African American labor leader A. Philip Randolph pressured Roosevelt with a threatened “March on Washington.” In response, the president signed Executive Order 8802, which created the Fair Employment Practices Committee to bar racial discrimination in the defense industry. While the committee was effective in forcing defense contractors, such as the DuPont Corporation, to hire African Americans, it was not able to force corporations to place African Americans in well-paid positions. For example, at DuPont’s plutonium production plant in Hanford, Washington, African Americans were hired as low-paid construction workers but not as laboratory technicians.
During the war, the Congress of Racial Equality (CORE), founded by James Farmer in 1942, used peaceful civil disobedience in the form of sit-ins to desegregate certain public spaces in Washington, DC, and elsewhere, as its contribution to the war effort. Members of CORE sought support for their movement by stating that one of their goals was to deprive the enemy of the ability to generate anti-American propaganda by accusing the United States of racism. After all, they argued, if the United States were going to denounce Germany and Japan for abusing human rights, the country should itself be as exemplary as possible. Indeed, CORE’s actions were in keeping with the goals of the Double V campaign that was begun in 1942 by the Pittsburgh Courier, the largest African American newspaper at the time (). The campaign called upon African Americans to accomplish the two “Vs”: victory over America’s foreign enemies and victory over racism in the United States.
Despite the willingness of African Americans to fight for the United States, racial tensions often erupted in violence, as the geographic relocation necessitated by the war brought African Americans into closer contact with White people. There were race riots in Detroit, Harlem, and Beaumont, Texas, in which White residents responded with sometimes deadly violence to their new Black coworkers or neighbors. There were also racial incidents at or near several military bases in the South. Incidents of African American soldiers being harassed or assaulted occurred at Fort Benning, Georgia; Fort Jackson, South Carolina; Alexandria, Louisiana; Fayetteville, Arkansas; and Tampa, Florida. African American leaders such as James Farmer and Walter White, the executive secretary of the NAACP since 1931, were asked by General Eisenhower to investigate complaints of the mistreatment of African American servicemen while on active duty. They prepared a fourteen-point memorandum on how to improve conditions for African Americans in the service, sowing some of the seeds of the postwar civil rights movement during the war years.
### The Zoot Suit Riots
Mexican Americans also encountered racial prejudice. The Mexican American population in Southern California grew during World War II due to the increased use of Mexican agricultural workers in the fields to replace the White workers who had left for better paying jobs in the defense industries. The United States and Mexican governments instituted the “bracero” program on August 4, 1942, which sought to address the needs of California growers for manual labor to increase food production during wartime. The result was the immigration of thousands of impoverished Mexicans into the United States to work as braceros, or manual laborers.
Forced by racial discrimination to live in the barrios of East Los Angeles, many Mexican American youths sought to create their own identity and began to adopt a distinctive style of dress known as zoot suits, which were also popular among many young African American men. The zoot suits, which required large amounts of cloth to produce, violated wartime regulations that restricted the amount of cloth that could be used in civilian garments. Among the charges leveled at young Mexican Americans was that they were un-American and unpatriotic; wearing zoot suits was seen as evidence of this. Many native-born Americans also denounced Mexican American men for being unwilling to serve in the military, even though some 350,000 Mexican Americans either volunteered to serve or were drafted into the armed services. In the summer of 1943, “zoot-suit riots” occurred in Los Angeles when carloads of White sailors, encouraged by other White civilians, stripped and beat a group of young men wearing the distinctive form of dress. In retaliation, young Mexican American men attacked and beat up sailors. The response was swift and severe, as sailors and civilians went on a spree attacking young Mexican Americans on the streets, in bars, and in movie theaters. More than one hundred people were injured.
### Internment
Japanese Americans also suffered from discrimination. The Japanese attack on Pearl Harbor unleashed a cascade of racist assumptions about Japanese immigrants and Japanese Americans in the United States that culminated in the relocation and internment of 120,000 people of Japanese ancestry, 66 percent of whom had been born in the United States. Executive Order 9066, signed by Roosevelt on February 19, 1942, gave the army power to remove people from “military areas” to prevent sabotage or espionage. The army then used this authority to relocate people of Japanese ancestry living along the Pacific coast of Washington, Oregon, and California, as well as in parts of Arizona, to internment camps in the American interior. Although a study commissioned earlier by Roosevelt indicated that there was little danger of disloyalty on the part of West Coast Japanese, fears of sabotage, perhaps spurred by the attempted rescue of a Japanese airman shot down at Pearl Harbor by Japanese living in Hawaii, and racist sentiments led Roosevelt to act. Ironically, Japanese in Hawaii were not interned. Although characterized afterwards as America’s worst wartime mistake by Eugene V. Rostow in the September 1945 edition of Harper’s Magazine, the government’s actions were in keeping with decades of anti-Asian sentiment on the West Coast.
After the order went into effect, Lt. General John L. DeWitt, in charge of the Western Defense command, ordered approximately 127,000 Japanese and Japanese Americans—roughly 90 percent of those of Japanese ethnicity living in the United States—to assembly centers where they were transferred to hastily prepared camps in the interior of California, Arizona, Colorado, Utah, Idaho, Wyoming, and Arkansas (). Those who were sent to the camps reported that the experience was deeply traumatic. Families were sometimes separated. People could only bring a few of their belongings and had to abandon the rest of their possessions. The camps themselves were dismal and overcrowded. Despite the hardships, the Japanese attempted to build communities in the camps and resume “normal” life. Adults participated in camp government and worked at a variety of jobs. Children attended school, played basketball against local teams, and organized Boy Scout units. Nevertheless, they were imprisoned, and minor infractions, such as wandering too near the camp gate or barbed wire fences while on an evening stroll, could meet with severe consequences. Some sixteen thousand Germans, including some from Latin America, and German Americans were also placed in internment camps, as were 2,373 persons of Italian ancestry. However, unlike the case with Japanese Americans, they represented only a tiny percentage of the members of these ethnic groups living in the country. Most of these people were innocent of any wrongdoing, but some Germans were members of the Nazi party. No interned Japanese Americans were found guilty of sabotage or espionage.
Despite being singled out for special treatment, many Japanese Americans sought to enlist, but draft boards commonly classified them as 4-C: undesirable aliens. However, as the war ground on, some were reclassified as eligible for service. In total, nearly thirty-three thousand Japanese Americans served in the military during the war. Of particular note was the 442nd Regimental Combat Team, which finished the war as the most decorated unit in U.S. military history given its size and length of service. While their successes, and the successes of the African American pilots, were lauded, the country and the military still struggled to contend with its own racial tensions, even as the soldiers in Europe faced the brutality of Nazi Germany.
### Section Summary
The brunt of the war’s damage occurred far from United States soil, but Americans at home were still greatly affected by the war. Women struggled to care for children with scarce resources at their disposal and sometimes while working full time. Economically, the country surged forward, but strict rationing for the war effort meant that Americans still went without. New employment opportunities opened up for women and ethnic minorities, as White men enlisted or were drafted. These new opportunities were positive for those who benefited from them, but they also created new anxieties among White men about racial and gender equality. Race riots took place across the country, and Americans of Japanese ancestry were relocated to internment camps. Still, there was an overwhelming sense of patriotism in the country, which was reflected in the culture of the day.
### Review Questions
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# Fighting the Good Fight in World War II, 1941-1945
## Victory in the European Theater
Despite the fact that a Japanese attack in the Pacific was the tripwire for America’s entrance into the war, Roosevelt had been concerned about Great Britain since the beginning of the Battle of Britain. Roosevelt viewed Germany as the greater threat to freedom. Hence, he leaned towards a “Europe First” strategy, even before the United States became an active belligerent. That meant that the United States would concentrate the majority of its resources and energies in achieving a victory over Germany first and then focus on defeating Japan. Within Europe, Churchill and Roosevelt were committed to saving Britain and acted with this goal in mind, often ignoring the needs of the Soviet Union. As Roosevelt imagined an “empire-free” postwar world, in keeping with the goals of the Atlantic Charter, he could also envision the United States becoming the preeminent world power economically, politically, and militarily.
### WARTIME DIPLOMACY
Franklin Roosevelt entered World War II with an eye toward a new postwar world, one where the United States would succeed Britain as the leader of Western capitalist democracies, replacing the old British imperial system with one based on free trade and decolonization. The goals of the Atlantic Charter had explicitly included self-determination, self-government, and free trade. In 1941, although Roosevelt had yet to meet Soviet premier Joseph Stalin, he had confidence that he could forge a positive relationship with him, a confidence that Churchill believed was born of naiveté. These allied leaders, known as the Big Three, thrown together by the necessity to defeat common enemies, took steps towards working in concert despite their differences.
Through a series of wartime conferences, Roosevelt and the other global leaders sought to come up with a strategy to both defeat the Germans and bolster relationships among allies. In January 1943, at Casablanca, Morocco, Churchill convinced Roosevelt to delay an invasion of France in favor of an invasion of Sicily (). It was also at this conference that Roosevelt enunciated the doctrine of “unconditional surrender.” Roosevelt agreed to demand an unconditional surrender from Germany and Japan to assure the Soviet Union that the United States would not negotiate a separate peace between the two belligerent states. He wanted a permanent transformation of Germany and Japan after the war. Roosevelt thought that announcing this as a specific war aim would discourage any nation or leader from seeking any negotiated armistice that would hinder efforts to reform and transform the defeated nations. Stalin, who was not at the conference, affirmed the concept of unconditional surrender when asked to do so. However, he was dismayed over the delay in establishing a “second front” along which the Americans and British would directly engage German forces in western Europe. A western front, brought about through an invasion across the English Channel, which Stalin had been demanding since 1941, offered the best means of drawing Germany away from the east. At a meeting in Tehran, Iran, also in November 1943, Churchill, Roosevelt, and Stalin met to finalize plans for a cross-channel invasion.
### THE INVASION OF EUROPE
Preparing to engage the Nazis in Europe, the United States landed in North Africa in 1942. The Axis campaigns in North Africa had begun when Italy declared war on England in June 1940, and British forces had invaded the Italian colony of Libya. The Italians had responded with a counteroffensive that penetrated into Egypt, only to be defeated by the British again. In response, Hitler dispatched the Afrika Korps under General Erwin Rommel, and the outcome of the situation was in doubt until shortly before American forces joined the British.
Although the Allied campaign secured control of the southern Mediterranean and preserved Egypt and the Suez Canal for the British, Stalin and the Soviets were still engaging hundreds of German divisions in bitter struggles at Stalingrad and Leningrad. The invasion of North Africa did nothing to draw German troops away from the Soviet Union. An invasion of Europe by way of Italy, which is what the British and American campaign in North Africa laid the ground for, pulled a few German divisions away from their Russian targets. But while Stalin urged his allies to invade France, British and American troops pursued the defeat of Mussolini’s Italy. This choice greatly frustrated Stalin, who felt that British interests were taking precedence over the agony that the Soviet Union was enduring at the hands of the invading German army. However, Churchill saw Italy as the vulnerable underbelly of Europe and believed that Italian support for Mussolini was waning, suggesting that victory there might be relatively easy. Moreover, Churchill pointed out that if Italy were taken out of the war, then the Allies would control the Mediterranean, offering the Allies easier shipping access to both the Soviet Union and the British Far Eastern colonies.
### D-Day
A direct assault on Nazi Germany’s “Fortress Europe” was still necessary for final victory. On June 6, 1944, the second front became a reality when Allied forces stormed the beaches of northern France on D-day. Beginning at 6:30 a.m., some twenty-four thousand British, Canadian, and American troops waded ashore along a fifty-mile piece of the Normandy coast (). Well over a million troops would follow their lead. German forces on the hills and cliffs above shot at them, and once they reached the beach, they encountered barbed wire and land mines. More than ten thousand Allied soldiers were wounded or killed during the assault. Following the establishment of beachheads at Normandy, it took months of difficult fighting before Paris was liberated on August 20, 1944. The invasion did succeed in diverting German forces from the eastern front to the western front, relieving some of the pressure on Stalin’s troops. By that time, however, Russian forces had already defeated the German army at Stalingrad, an event that many consider the turning point of the war in Europe, and begun to push the Germans out of the Soviet Union.
Nazi Germany was not ready to surrender, however. On December 16, in a surprise move, the Germans threw nearly a quarter-million men at the Western Allies in an attempt to divide their armies and encircle major elements of the American forces. The struggle, known as the Battle of the Bulge, raged until the end of January. Some ninety thousand Americans were killed, wounded, or lost in action. Nevertheless, the Germans were turned back, and Hitler’s forces were so spent that they could never again mount offensive operations.
### Confronting the Holocaust
The Holocaust, Hitler’s plan to kill the Jews of Europe, had begun as early as 1933, with the construction of Dachau, the first of more than forty thousand camps for incarcerating Jews, submitting them to forced labor, or exterminating them. Eventually, six extermination camps were established between 1941 and 1945 in Polish territory. Jewish men, women, and children from throughout Europe were transported to these camps in Germany and other areas under Nazi control. Although the majority of the people in the camps were Jews, the Nazis sent Roma (gypsies), gays and lesbians, Jehovah’s Witnesses, and political opponents to the camps as well. Some prisoners were put to work at hard labor; many of them subsequently died of disease or starvation. Most of those sent to the extermination camps were killed upon arrival with poisoned gas. Ultimately, some eleven million people died in the camps. As Soviet troops began to advance from the east and U.S. forces from the west, camp guards attempted to hide the evidence of their crimes by destroying records and camp buildings, and marching surviving prisoners away from the sites ().
### YALTA AND PREPARING FOR VICTORY
The last time the Big Three met was in early February 1945 at Yalta in the Soviet Union. Roosevelt was sick, and Stalin’s armies were pushing the German army back towards Berlin from the east. Churchill and Roosevelt thus had to accept a number of compromises that strengthened Stalin’s position in eastern Europe. In particular, they agreed to allow the Communist government installed by the Soviet Union in Poland to remain in power until free elections took place. For his part, Stalin reaffirmed his commitment, first voiced at Tehran, to enter the war against Japan following the surrender of Germany (). He also agreed that the Soviet Union would participate in the United Nations, a new peacekeeping body intended to replace the League of Nations. The Big Three left Yalta with many details remaining unclear, planning to finalize plans for the treatment of Germany and the shape of postwar Europe at a later conference. However, Roosevelt did not live to attend the next meeting. He died on April 12, 1945, and Harry S. Truman became president.
By April 1945, Soviet forces had reached Berlin, and both the U.S. and British Allies were pushing up against Germany’s last defenses in the western part of the nation. Hitler committed suicide on April 30, 1945. On May 8, 1945, Germany surrendered. The war in Europe was over, and the Allies and liberated regions celebrated the end of the long ordeal. Germany was thoroughly defeated; its industries and cities were badly damaged.
The victorious Allies set about determining what to do to rebuild Europe at the Potsdam Summit Conference in July 1945. Attending the conference were Stalin, Truman, and Churchill, now the outgoing prime minister, as well as the new British prime minister, Clement Atlee. Plans to divide Germany and Austria, and their capital cities, into four zones—to be occupied by the British, French, Americans, and Soviets—a subject discussed at Yalta, were finalized. In addition, the Allies agreed to dismantle Germany’s heavy industry in order to make it impossible for the country to produce more armaments.
### Section Summary
Upon entering the war, President Roosevelt believed that the greatest threat to the long-term survival of democracy and freedom would be a German victory. Hence, he entered into an alliance with British prime minister Winston Churchill and Soviet premier Joseph Stalin to defeat the common enemy while also seeking to lay the foundation for a peaceful postwar world in which the United States would play a major and permanent role. Appeasement and nonintervention had been proven to be shortsighted and tragic policies that failed to provide security and peace either for the United States or for the world.
With the aid of the British, the United States invaded North Africa and from there invaded Europe by way of Italy. However, the cross-channel invasion of Europe through France that Stalin had long called for did not come until 1944, by which time the Soviets had turned the tide of battle in eastern Europe. The liberation of Hitler’s concentration camps forced Allied nations to confront the grisly horrors that had been taking place as the war unfolded. The Big Three met for one last time in February 1945, at Yalta, where Churchill and Roosevelt agreed to several conditions that strengthened Stalin’s position. They planned to finalize their plans at a later conference, but Roosevelt died two months later.
### Review Questions
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# Fighting the Good Fight in World War II, 1941-1945
## The Pacific Theater and the Atomic Bomb
Japanese forces won a series of early victories against Allied forces from December 1941 to May 1942. They seized Guam and Wake Island from the United States, and streamed through Malaysia and Thailand into the Philippines and through the Dutch East Indies. By February 1942, they were threatening Australia. The Allies turned the tide in May and June 1942, at the Battle of Coral Sea and the Battle of Midway. The Battle of Midway witnessed the first Japanese naval defeat since the nineteenth century. Shortly after the American victory, U.S. forces invaded Guadalcanal and New Guinea. Slowly, throughout 1943, the United States engaged in a campaign of “island hopping,” gradually moving across the Pacific to Japan. In 1944, the United States, seized Saipan and won the Battle of the Philippine Sea. Progressively, American forces drew closer to the strategically important targets of Iwo Jima and Okinawa.
### THE PACIFIC CAMPAIGN
During the 1930s, Americans had caught glimpses of Japanese armies in action and grew increasingly sympathetic towards war-torn China. Stories of Japanese atrocities bordering on genocide and the shock of the attack on Pearl Harbor intensified racial animosity toward the Japanese. Wartime propaganda portrayed Japanese soldiers as uncivilized and barbaric, sometimes even inhuman (), unlike America’s German foes. Admiral William Halsey spoke for many Americans when he urged them to “Kill Japs! Kill Japs! Kill more Japs!” Stories of the dispiriting defeats at Bataan and the Japanese capture of the Philippines at Corregidor in 1942 revealed the Japanese cruelty and mistreatment of Americans. The “Bataan Death March,” during which as many as 650 American and 10,000 Filipino prisoners of war died, intensified anti-Japanese feelings. Kamikaze attacks that took place towards the end of the war were regarded as proof of the irrationality of Japanese martial values and mindless loyalty to Emperor Hirohito.
Despite the Allies’ Europe First strategy, American forces took the resources that they could assemble and swung into action as quickly as they could to blunt the Japanese advance. Infuriated by stories of defeat at the hands of the allegedly racially inferior Japanese, many high-ranking American military leaders demanded that greater attention be paid to the Pacific campaign. Rather than simply wait for the invasion of France to begin, naval and army officers such as General Douglas MacArthur argued that American resources should be deployed in the Pacific to reclaim territory seized by Japan.
In the Pacific, MacArthur and the Allied forces pursued an island hopping strategy that bypassed certain island strongholds held by the Japanese that were of little or no strategic value. By seizing locations from which Japanese communications and transportation routes could be disrupted or destroyed, the Allies advanced towards Japan without engaging the thousands of Japanese stationed on garrisoned islands. The goal was to advance American air strength close enough to Japan proper to achieve air superiority over the home islands; the nation could then be bombed into submission or at least weakened in preparation for an amphibious assault. By February 1945, American forces had reached the island of Iwo Jima (). Iwo Jima was originally meant to serve as a forward air base for fighter planes, providing cover for long-distance bombing raids on Japan. Two months later, an even larger engagement, the hardest fought and bloodiest battle of the Pacific theater, took place as American forces invaded Okinawa. The battle raged from April 1945 well into July 1945; the island was finally secured at the cost of seventeen thousand American soldiers killed and thirty-six thousand wounded. Japanese forces lost over 100,000 troops. Perhaps as many as 150,000 civilians perished as well.
### DROPPING THE ATOMIC BOMB
All belligerents in World War II sought to develop powerful and devastating weaponry. As early as 1939, German scientists had discovered how to split uranium atoms, the technology that would ultimately allow for the creation of the atomic bomb. Albert Einstein, who had emigrated to the United States in 1933 to escape the Nazis, urged President Roosevelt to launch an American atomic research project, and Roosevelt agreed to do so, with reservations. In late 1941, the program received its code name: the Manhattan Project. Located at Los Alamos, New Mexico, the Manhattan Project ultimately employed 150,000 people and cost some $2 billion. In July 1945, the project’s scientists successfully tested the first atomic bomb.
In the spring of 1945, the military began to prepare for the possible use of an atomic bomb by choosing appropriate targets. Suspecting that the immediate bomb blast would extend over one mile and secondary effects would include fire damage, a compact city of significant military value with densely built frame buildings seemed to be the best target. Eventually, the city of Hiroshima, the headquarters of the Japanese Second Army, and the communications and supply hub for all of southern Japan, was chosen. The city of Kokura was chosen as the primary target of the second bomb, and Nagasaki, an industrial center producing war materiel and the largest seaport in southern Japan, was selected as a secondary target.
The , a B-29 bomber named after its pilot’s mother, dropped an atomic bomb known as “Little Boy” on Hiroshima at 8:15 a.m. Monday morning, August 6, 1945. A huge mushroom cloud rose above the city. Survivors sitting down for breakfast or preparing to go to school recalled seeing a bright light and then being blown across the room. The immense heat of the blast melted stone and metal, and ignited fires throughout the city. One man later recalled watching his mother and brother burn to death as fire consumed their home. A female survivor, a child at the time of the attack, remembered finding the body of her mother, which had been reduced to ashes and fell apart as she touched it. Two-thirds of the buildings in Hiroshima were destroyed. Within an hour after the bombing, radioactive “black rain” began to fall. Approximately seventy thousand people died in the original blast. The same number would later die of radiation poisoning. When Japan refused to surrender, a second atomic bomb, named Fat Man, was dropped on Nagasaki on August 9, 1945. At least sixty thousand people were killed at Nagasaki. Kokura, the primary target, had been shrouded in clouds on that morning and thus had escaped destruction. It is impossible to say with certainty how many died in the two attacks; the heat of the bomb blasts incinerated or vaporized many of the victims ().
The decision to use nuclear weapons is widely debated. Why exactly did the United States deploy an atomic bomb? The fierce resistance that the Japanese forces mounted during their early campaigns led American planners to believe that any invasion of the Japanese home islands would be exceedingly bloody. According to some estimates, as many as 250,000 Americans might die in securing a final victory. Such considerations undoubtedly influenced President Truman’s decision. Truman, who had not known about the Manhattan Project until Roosevelt’s death, also may not have realized how truly destructive it was. Indeed, some of the scientists who had built the bomb were surprised by its power. One question that has not been fully answered is why the United States dropped the second bomb on Nagasaki. As some scholars have noted, if Truman’s intention was to eliminate the need for a home island invasion, he could have given Japan more time to respond after bombing Hiroshima. He did not, however. The second bombing may have been intended to send a message to Stalin, who was becoming intransigent regarding postwar Europe. If it is indeed true that Truman had political motivations for using the bombs, then the destruction of Nagasaki might have been the first salvo of the Cold War with the Soviet Union. And yet, other historians have pointed out that the war had unleashed such massive atrocities against civilians by all belligerents—the United States included—that by the summer of 1945, the president no longer needed any particular reason to use his entire nuclear arsenal.
### THE WAR ENDS
Whatever the true reasons for their use, the bombs had the desired effect of getting Japan to surrender. Even before the atomic attacks, the conventional bombings of Japan, the defeat of its forces in the field, and the entry of the Soviet Union into the war had convinced the Imperial Council that they had to end the war. They had hoped to negotiate the terms of the peace, but Emperor Hirohito intervened after the destruction of Nagasaki and accepted unconditional surrender. Although many Japanese shuddered at the humiliation of defeat, most were relieved that the war was over. Japan’s industries and cities had been thoroughly destroyed, and the immediate future looked bleak as they awaited their fate at the hands of the American occupation forces.
The victors had yet another nation to rebuild and reform, but the war was finally over. Following the surrender, the Japanese colony of Korea was divided along the thirty-eighth parallel; the Soviet Union was given control of the northern half and the United States was given control of the southern portion. In Europe, as had been agreed upon at a meeting of the Allies in Potsdam in the summer of 1945, Germany was divided into four occupation zones that would be controlled by Britain, France, the Soviet Union, and the United States, respectively. The city of Berlin was similarly split into four. Plans were made to prosecute war criminals in both Japan and Germany. In October 1945, the United Nations was created. People around the world celebrated the end of the conflict, but America’s use of atomic bombs and disagreements between the United States and the Soviet Union at Yalta and Potsdam would contribute to ongoing instability in the postwar world.
### Section Summary
The way in which the United States fought the war in the Pacific was fueled by fear of Japanese imperialistic aggression, as well as anger over Japan’s attack on Pearl Harbor and its mistreatment of its enemies. It was also influenced by a long history of American racism towards Asians that dated back to the nineteenth century. From hostile anti-Japanese propaganda to the use of two atomic bombs on Japanese cities, America’s actions during the Pacific campaign were far more aggressive than they were in the European theater. Using the strategy of island hopping, the United States was able to get within striking distance of Japan. Only once they adopted this strategy were the Allied troops able to turn the tide against what had been a series of challenging Japanese victories. The war ended with Japan’s surrender.
The combined Allied forces had successfully waged a crusade against Nazi Germany, Italy, and Japan. The United States, forced to abandon a policy of nonintervention outside the Western Hemisphere, had been able to mobilize itself and produce the weapons and the warriors necessary to defeat its enemies. Following World War II, America would never again retreat from the global stage, and its early mastery of nuclear weapons would make it the dominant force in the postwar world.
### Review Questions
### Critical Thinking Questions
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# Post-War Prosperity and Cold War Fears, 1945-1960
## Introduction
Is This Tomorrow? (), a 1947 comic book, highlights one way that the federal government and some Americans revived popular sentiment in opposition to Communism. The United States and the Soviet Union, allies during World War II, had different visions for the postwar world. As Joseph Stalin, premier of the Soviet Union, tightened his grip on the countries of Eastern Europe, Americans began to fear that it was his goal to spread the Communist revolution throughout the world and make newly independent nations puppets of the Soviet Union. To enlist as many Americans as possible in the fight against Soviet domination, the U.S. government and purveyors of popular culture churned out propaganda intended to convince average citizens of the dangers posed by the Soviet Union. Artwork such as the cover of Is This Tomorrow?, which depicts Russians attacking Americans, including a struggling woman and an African American veteran still wearing his uniform, played upon postwar fears of Communism and of a future war with the Soviet Union. These fears dominated American life and affected foreign policy, military strategy, urban planning, popular culture, and the civil rights movement. |
# Post-War Prosperity and Cold War Fears, 1945-1960
## The Challenges of Peacetime
The decade and a half immediately following the end of World War II was one in which middle- and working-class Americans hoped for a better life than the one they lived before the war. These hopes were tainted by fears of economic hardship, as many who experienced the Great Depression feared a return to economic decline. Others clamored for the opportunity to spend the savings they had accumulated through long hours on the job during the war when consumer goods were rarely available.
African Americans who had served in the armed forces and worked in the defense industry did not wish to return to “normal.” Instead, they wanted the same rights and opportunities that other Americans had. Still other citizens were less concerned with the economy or civil rights; instead, they looked with suspicion at the Soviet presence in Eastern Europe. What would happen now that the United States and the Soviet Union were no longer allies, and the other nations that had long helped maintain a balance of power were left seriously damaged by the war? Harry Truman, president for less than a year when the war ended, was charged with addressing all of these concerns and giving the American people a “fair deal.”
### DEMOBILIZATION AND THE RETURN TO CIVILIAN LIFE
The most immediate task to be completed after World War II was demobilizing the military and reintegrating the veterans into civilian life. In response to popular pressure and concerns over the budget, the United States sought to demobilize its armed forces as quickly as possible. Many servicemen, labeled the “Ohio boys” (Over the Hill in October), threatened to vote Republican if they were not home by Christmas 1946. Understandably, this placed a great deal of pressure on the still-inexperienced president to shrink the size of the U.S. military.
Not everyone wanted the government to reduce America’s military might, however. Secretary of the Navy James Forrestal and Secretary of War Robert P. Patterson warned Truman in October 1945 that an overly rapid demobilization jeopardized the nation’s strategic position in the world. While Truman agreed with their assessment, he felt powerless to put a halt to demobilization. In response to mounting political pressure, the government reduced the size of the U.S. military from a high of 12 million in June 1945 to 1.5 million in June 1947—still more troops than the nation ever had in arms during peacetime. Soldiers and sailors were not the only ones dismissed from service. As the war drew to a close, millions of women working the jobs of men who had gone off to fight were dismissed by their employers, often because the demand for war materiel had declined and because government propaganda encouraged them to go home to make way for the returning troops. While most women workers surveyed at the end of the war wished to keep their jobs (75–90 percent, depending on the study), many did in fact leave them. Nevertheless, throughout the late 1940s and the 1950s, women continued to make up approximately one-third of the U.S. labor force.
Readjustment to postwar life was difficult for the returning troops. The U.S. Army estimated that as many of 20 percent of its casualties were psychological. Although many eagerly awaited their return to civilian status, others feared that they would not be able to resume a humdrum existence after the experience of fighting on the front lines. Veterans also worried that they wouldn’t find work and that civilian defense workers were better positioned to take advantage of the new jobs opening up in the peacetime economy. Some felt that their wives and children would not welcome their presence, and some children did indeed resent the return of fathers who threatened to disrupt the mother-child household. Those on the home front worried as well. Doctors warned fiancées, wives, and mothers that soldiers might return with psychological problems that would make them difficult to live with.
### The GI Bill of Rights
Well before the end of the war, Congress had passed one of the most significant and far-reaching pieces of legislation to ease veterans’ transition into civilian life: the Servicemen’s Readjustment Act, also known as the GI Bill (). Every honorably discharged veteran who had seen active duty, but not necessarily combat, was eligible to receive a year’s worth of unemployment compensation. This provision not only calmed veterans’ fears regarding their ability to support themselves, but it also prevented large numbers of men—as well as some women—from suddenly entering a job market that did not have enough positions for them. Another way that the GI Bill averted a glut in the labor market was by giving returning veterans the opportunity to pursue an education; it paid for tuition at a college or vocational school, and gave them a stipend to live on while they completed their studies.
The result was a dramatic increase in the number of students—especially male ones—enrolled in American colleges and universities. In 1940, only 5.5 percent of American men had a college degree. By 1950, that percentage had increased to 7.3 percent, as more than two million servicemen took advantage of the benefits offered by the GI Bill to complete college. The numbers continued to grow throughout the 1950s. Upon graduation, these men were prepared for skilled blue-collar or white-collar jobs that paved the way for many to enter the middle class. The creation of a well-educated, skilled labor force helped the U.S. economy as well. Other benefits offered by the GI Bill included low-interest loans to purchase homes or start small businesses.
However, not all veterans were able to take advantage of the GI Bill. African American veterans could use their educational benefits only to attend schools that accepted Black students. The approximately nine thousand servicemen and women who were dishonorably discharged because they were gay or lesbian were ineligible for GI Bill benefits. Benefits for some Mexican American veterans, mainly in Texas, were also denied or delayed.
### The Return of the Japanese
While most veterans received assistance to help in their adjustment to postwar life, others returned home to an uncertain future without the promise of government aid to help them resume their prewar lives. Japanese Americans from the West Coast who had been interned during the war also confronted the task of rebuilding their lives. In December 1944, Franklin Roosevelt had declared an end to the forced relocation of Japanese Americans, and as of January 1945, they were free to return to their homes. In many areas, however, neighbors clung to their prejudices and denounced those of Japanese descent as disloyal and dangerous. These feelings had been worsened by wartime propaganda, which often featured horrific accounts of Japanese mistreatment of prisoners, and by the statements of military officers to the effect that the Japanese were inherently savage. Facing such animosity, many Japanese American families chose to move elsewhere. Those who did return often found that in their absence, “friends” and neighbors had sold possessions that had been left with them for safekeeping. Many homes had been vandalized and farms destroyed. When Japanese Americans reopened their businesses, former customers sometimes boycotted them.
### THE FAIR DEAL
Early in his presidency, Truman sought to build on the promises of Roosevelt’s New Deal. Besides demobilizing the armed forces and preparing for the homecoming of servicemen and women, he also had to guide the nation through the process of returning to a peacetime economy. To this end, he proposed an ambitious program of social legislation that included establishing a federal minimum wage, expanding Social Security and public housing, and prohibiting child labor. Wartime price controls were retained for some items but removed from others, like meat. In his 1949 inaugural address, Truman referred to his programs as the “Fair Deal,” a nod to his predecessor’s New Deal. He wanted the Fair Deal to include Americans of color and became the first president to address the National Association for the Advancement of Colored People (NAACP). He also took decisive steps towards extending civil rights to African Americans by establishing, by executive order in December 1946, a Presidential Committee on Civil Rights to investigate racial discrimination in the United States. Truman also desegregated the armed forces, again by executive order, in July 1948, overriding many objections that the military was no place for social experimentation.
Congress, however, which was dominated by Republicans and southern conservative Democrats, refused to pass more “radical” pieces of legislation, such as a bill providing for national healthcare. The American Medical Association spent some $1.5 million to defeat Truman’s healthcare proposal, which it sought to discredit as socialized medicine in order to appeal to Americans’ fear of Communism. The same Congress also refused to make lynching a federal crime or outlaw the poll tax that reduced the access of poor Americans to the ballot box. Congress also rejected a bill that would have made Roosevelt’s Fair Employment Practices Committee, which prohibited racial discrimination by companies doing business with the federal government, permanent. At the same time, they passed many conservative pieces of legislation. For example, the Taft-Hartley Act, which limited the power of unions, became law despite Truman’s veto.
### Section Summary
At the end of World War II, U.S. servicemen and women returned to civilian life, and all hoped the prosperity of the war years would continue. The GI Bill eased many veterans’ return by providing them with unemployment compensation, low-interest loans, and money to further their education; however, African American, Mexican American, and gay veterans were often unable to take advantage of these benefits fully or at all. Meanwhile, Japanese Americans faced an uphill struggle in their attempts to return to normalcy, and many women who had made significant professional gains in wartime found themselves dismissed from their positions. President Harry Truman attempted to extend Roosevelt’s New Deal with his own Fair Deal, which had the goal of improving wages, housing, and healthcare, and protecting the rights of African Americans. Confronted by a Congress dominated by Republicans and southern Democrats, however, Truman was able to achieve only some of his goals.
### Review Questions
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# Post-War Prosperity and Cold War Fears, 1945-1960
## The Cold War
As World War II drew to a close, the alliance that had made the United States and the Soviet Union partners in their defeat of the Axis powers—Germany, Italy, and Japan—began to fall apart. Both sides realized that their visions for the future of Europe and the world were incompatible. Joseph Stalin, the premier of the Soviet Union, wished to retain hold of Eastern Europe and establish Communist, pro-Soviet governments there, in an effort to both expand Soviet influence and protect the Soviet Union from future invasions. He also sought to bring Communist revolution to Asia and to developing nations elsewhere in the world. The United States wanted to expand its influence as well by protecting or installing democratic governments throughout the world. It sought to combat the influence of the Soviet Union by forming alliances with Asian, African, and Latin American nations, and by helping these countries to establish or expand prosperous, free-market economies. The end of the war left the industrialized nations of Europe and Asia physically devastated and economically exhausted by years of invasion, battle, and bombardment. With Great Britain, France, Germany, Italy, Japan, and China reduced to shadows of their former selves, the United States and the Soviet Union emerged as the last two superpowers and quickly found themselves locked in a contest for military, economic, social, technological, and ideological supremacy.
### FROM ISOLATIONISM TO ENGAGEMENT
The United States had a long history of avoiding foreign alliances that might require the commitment of its troops abroad. However, in accepting the realities of the post-World War II world, in which traditional powers like Great Britain or France were no longer strong enough to police the globe, the United States realized that it would have to make a permanent change in its foreign policy, shifting from relative isolation to active engagement.
On assuming the office of president upon the death of Franklin Roosevelt, Harry Truman was already troubled by Soviet actions in Europe. He disliked the concessions made by Roosevelt at Yalta, which had allowed the Soviet Union to install a Communist government in Poland. At the Potsdam conference, held from July 17 to August 2, 1945, Truman also opposed Stalin’s plans to demand large reparations from Germany. He feared the burden that this would impose on Germany might lead to another cycle of German rearmament and aggression—a fear based on that nation’s development after World War I ().
Although the United States and the Soviet Union did finally reach an agreement at Potsdam, this was the final occasion on which they cooperated for quite some time. Each remained convinced that its own economic and political systems were superior to the other’s, and the two superpowers quickly found themselves drawn into conflict. The decades-long struggle between them for technological and ideological supremacy became known as the Cold War. So called because it did not include direct military confrontation between Soviet and U.S. troops, the Cold War was fought with a variety of other weapons: espionage and surveillance, political assassinations, propaganda, and the formation of alliances with other nations. It also became an arms race, as both countries competed to build the greatest stockpile of nuclear weapons, and also competed for influence in poorer nations, supporting opposite sides in wars in some of those nations, such as Korea and Vietnam.
### CONTAINMENT ABROAD
In February 1946, George Kennan, a State Department official stationed at the U.S. embassy in Moscow, sent an eight-thousand-word message to Washington, DC. In what became known as the “Long Telegram,” Kennan maintained that Soviet leaders believed that the only way to protect the Soviet Union was to destroy “rival” nations and their influence over weaker nations. According to Kennan, the Soviet Union was not so much a revolutionary regime as a totalitarian bureaucracy that was unable to accept the prospect of a peaceful coexistence of the United States and itself. He advised that the best way to thwart Soviet plans for the world was to contain Soviet influence—primarily through economic policy—to those places where it already existed and prevent its political expansion into new areas. This strategy, which came to be known as the policy of containment, formed the basis for U.S. foreign policy and military decision making for more than thirty years.
As Communist governments came to power elsewhere in the world, American policymakers extended their strategy of containment to what became known as the domino theory under the Eisenhower administration: Neighbors to Communist nations, so was the assumption, were likely to succumb to the same allegedly dangerous and infectious ideology. Like dominos toppling one another, entire regions would eventually be controlled by the Soviets. The demand for anti-Communist containment appeared as early as March 1946 in a speech by Winston Churchill, in which he referred to an Iron Curtain that divided Europe into the “free” West and the Communist East controlled by the Soviet Union.
The commitment to containing Soviet expansion made necessary the ability to mount a strong military offense and defense. In pursuit of this goal, the U.S. military was reorganized under the National Security Act of 1947. This act streamlined the government in matters of security by creating the National Security Council and establishing the Central Intelligence Agency (CIA) to conduct surveillance and espionage in foreign nations. It also created the Department of the Air Force, which was combined with the Departments of the Army and Navy in 1949 to form one Department of Defense.
### The Truman Doctrine
In Europe, the end of World War II witnessed the rise of a number of internal struggles for control of countries that had been occupied by Nazi Germany. Great Britain occupied Greece as the Nazi regime there collapsed. The British aided the authoritarian government of Greece in its battles against Greek Communists. In March 1947, Great Britain announced that it could no longer afford the cost of supporting government military activities and withdrew from participation in the Greek civil war. Stepping into this power vacuum, the United States announced the Truman Doctrine, which offered support to Greece and Turkey in the form of financial assistance, weaponry, and troops to help train their militaries and bolster their governments against Communism. Eventually, the program was expanded to include any state trying to withstand a Communist takeover. The Truman Doctrine thus became a hallmark of U.S. Cold War policy.
### The Marshall Plan
By 1946, the American economy was growing significantly. At the same time, the economic situation in Europe was disastrous. The war had turned much of Western Europe into a battlefield, and the rebuilding of factories, public transportation systems, and power stations progressed exceedingly slowly. Starvation loomed as a real possibility for many. As a result of these conditions, Communism was making significant inroads in both Italy and France. These concerns led Truman, along with Secretary of State George C. Marshall, to propose to Congress the European Recovery Program, popularly known as the Marshall Plan. Between its implementation in April 1948 and its termination in 1951, this program gave $13 billion in economic aid to European nations.
Truman’s motivation was economic and political, as well as humanitarian. The plan stipulated that the European nations had to work together in order to receive aid, thus enforcing unity through enticement, while seeking to undercut the political popularity of French and Italian Communists and dissuading moderates from forming coalition governments with them. Likewise, much of the money had to be spent on American goods, boosting the postwar economy of the United States as well as the American cultural presence in Europe. Stalin regarded the program as a form of bribery. The Soviet Union refused to accept aid from the Marshall Plan, even though it could have done so, and forbade the Communist states of Eastern Europe to accept U.S. funds as well. Those states that did accept aid began to experience an economic recovery.
### Showdown in Europe
The lack of consensus with the Soviets on the future of Germany led the United States, Great Britain, and France to support joining their respective occupation zones into a single, independent state. In December 1946, they took steps to do so, but the Soviet Union did not wish the western zones of the country to unify under a democratic, pro-capitalist government. The Soviet Union also feared the possibility of a unified West Berlin, located entirely within the Soviet sector. Three days after the western allies authorized the introduction of a new currency in Western Germany—the Deutsche Mark—Stalin ordered all land and water routes to the western zones of the city Berlin to be cut off in June 1948. Hoping to starve the western parts of the city into submission, the Berlin blockade was also a test of the emerging U.S. policy of containment.
Unwilling to abandon Berlin, the United States, Great Britain, and France began to deliver all needed supplies to West Berlin by air (). In April 1949, the three countries joined Canada and eight Western European nations to form the North Atlantic Treaty Organization (NATO), an alliance pledging its members to mutual defense in the event of attack. On May 12, 1949, a year and approximately two million tons of supplies later, the Soviets admitted defeat and ended the blockade of Berlin. On May 23, the Federal Republic of Germany (FRG), consisting of the unified western zones and commonly referred to as West Germany, was formed. The Soviets responded by creating the German Democratic Republic, or East Germany, in October 1949.
### CONTAINMENT AT HOME
In 1949, two incidents severely disrupted American confidence in the ability of the United States to contain the spread of Communism and limit Soviet power in the world. First, on August 29, 1949, the Soviet Union exploded its first atomic bomb—no longer did the United States have a monopoly on nuclear power. A few months later, on October 1, 1949, Chinese Communist Party leader Mao Zedong announced the triumph of the Chinese Communists over their Nationalist foes in a civil war that had been raging since 1927. The Nationalist forces, under their leader Chiang Kai-shek, departed for Taiwan in December 1949.
Immediately, there were suspicions that spies had passed bomb-making secrets to the Soviets and that Communist sympathizers in the U.S. State Department had hidden information that might have enabled the United States to ward off the Communist victory in China. Indeed, in February 1950, Wisconsin senator Joseph McCarthy, a Republican, charged in a speech that the State Department was filled with Communists. Also in 1950, the imprisonment in Great Britain of Klaus Fuchs, a German-born physicist who had worked on the Manhattan Project and was then convicted of passing nuclear secrets to the Soviets, increased American fears. Information given by Fuchs to the British implicated a number of American citizens as well. The most infamous trial of suspected American spies was that of Julius and Ethel Rosenberg, who were executed in June 1953 despite a lack of evidence against them. Several decades later, evidence was found that Julius, but not Ethel, had in fact given information to the Soviet Union.
Fears that Communists within the United States were jeopardizing the country’s security had existed even before the victory of Mao Zedong and the arrest and conviction of the atomic spies. Roosevelt’s New Deal and Truman’s Fair Deal were often criticized as “socialist,” which many mistakenly associated with Communism, and Democrats were often branded Communists by Republicans. In response, on March 21, 1947, Truman signed Executive Order 9835, which provided the Federal Bureau of Investigation with broad powers to investigate federal employees and identify potential security risks. State and municipal governments instituted their own loyalty boards to find and dismiss potentially disloyal workers.
In addition to loyalty review boards, the House Committee on Un-American Activities (HUAC) was established in 1938 to investigate claims of disloyalty and subversive activities among private citizens. It directed much of its attention to rooting out suspected Communists in business, academia, and the media. HUAC was particularly interested in Hollywood because it feared that Communist sympathizers might use motion pictures as pro-Soviet propaganda. Witnesses were subpoenaed and required to testify before the committee; refusal could result in imprisonment. Those who invoked Fifth Amendment protections, or were otherwise suspected of Communist sympathies, often lost their jobs or found themselves on a blacklist, which prevented them from securing employment. Notable artists who were blacklisted in the 1940s and 1950s include composer Leonard Bernstein, novelist Dashiell Hammett, playwright and screenwriter Lillian Hellman, actor and singer Paul Robeson, and musician Artie Shaw.
### TO THE TRENCHES AGAIN
Just as the U.S. government feared the possibility of Communist infiltration of the United States, so too was it alert for signs that Communist forces were on the move elsewhere. The Soviet Union had been granted control of the northern half of the Korean peninsula at the end of World War II, and the United States had control of the southern portion. The Soviets displayed little interest in extending its power into South Korea, and Stalin did not wish to risk confrontation with the United States over Korea. North Korea’s leaders, however, wished to reunify the peninsula under Communist rule. In April 1950, Stalin finally gave permission to North Korea’s leader Kim Il Sung to invade South Korea and provided the North Koreans with weapons and military advisors.
On June 25, 1950, troops of the North Korean People’s Democratic Army crossed the thirty-eighth parallel, the border between North and South Korea. The first major test of the U.S. policy of containment in Asia had begun, for the domino theory held that a victory by North Korea might lead to further Communist expansion in Asia, in the virtual backyard of the United States’ chief new ally in East Asia—Japan. The United Nations (UN), which had been established in 1945, was quick to react. On June 27, the UN Security Council denounced North Korea’s actions and called upon UN members to help South Korea defeat the invading forces. As a permanent member of the Security Council, the Soviet Union could have vetoed the action, but it had boycotted UN meetings following the awarding of China’s seat on the Security Council to Taiwan instead of to Mao Zedong’s People’s Republic of China.
On June 27, Truman ordered U.S. military forces into South Korea. They established a defensive line on the far southern part of the Korean peninsula near the town of Pusan. A U.S.-led invasion at Inchon on September 15 halted the North Korean advance and turned it into a retreat (). As North Korean forces moved back across the thirty-eighth parallel, UN forces under the command of U.S. General Douglas MacArthur followed. MacArthur’s goal was not only to drive the North Korean army out of South Korea but to destroy Communist North Korea as well. At this stage, he had the support of President Truman; however, as UN forces approached the Yalu River, the border between China and North Korea, MacArthur’s and Truman’s objectives diverged. Chinese premier Zhou Enlai, who had provided supplies and military advisors for North Korea before the conflict began, sent troops into battle to support North Korea and caught U.S. troops by surprise. Following a costly retreat from North Korea’s Chosin Reservoir, a swift advance of Chinese and North Korean forces and another invasion of Seoul, MacArthur urged Truman to deploy nuclear weapons against China. Truman, however, did not wish to risk a broader war in Asia. MacArthur criticized Truman’s decision and voiced his disagreement in a letter to a Republican congressman, who subsequently allowed the letter to become public. In April 1951, Truman accused MacArthur of insubordination and relieved him of his command. The Joint Chiefs of Staff agreed, calling the escalation MacArthur had called for “the wrong war, at the wrong place, at the wrong time, and with the wrong enemy.” Nonetheless, the public gave MacArthur a hero’s welcome in New York with the largest ticker tape parade in the nation’s history.
By July 1951, the UN forces had recovered from the setbacks earlier in the year and pushed North Korean and Chinese forces back across the thirty-eighth parallel, and peace talks began. However, combat raged on for more than two additional years. The primary source of contention was the fate of prisoners of war. The Chinese and North Koreans insisted that their prisoners be returned to them, but many of these men did not wish to be repatriated. Finally, an armistice agreement was signed on July 27, 1953. A border between North and South Korea, one quite close to the original thirty-eighth parallel line, was agreed upon. A demilitarized zone between the two nations was established, and both sides agreed that prisoners of war would be allowed to choose whether to be returned to their homelands. Five million people died in the three-year conflict. Of these, around 36,500 were U.S. soldiers; a majority were Korean civilians.
As the war in Korea came to an end, so did one of the most frightening anti-Communist campaigns in the United States. After charging the U.S. State Department with harboring Communists, Senator Joseph McCarthy had continued to make similar accusations against other government agencies. Prominent Republicans like Senator Robert Taft and Congressman Richard Nixon regarded McCarthy as an asset who targeted Democratic politicians, and they supported his actions. In 1953, as chair of the Senate Committee on Government Operations, McCarthy investigated the Voice of America, which broadcast news and pro-U.S. propaganda to foreign countries, and the State Department’s overseas libraries. After an aborted effort to investigate Protestant clergy, McCarthy turned his attention to the U.S. Army. This proved to be the end of the senator’s political career. From April to June 1954, the Army-McCarthy Hearings were televised, and the American public, able to witness his use of intimidation and innuendo firsthand, rejected McCarthy’s approach to rooting out Communism in the United States (). In December 1954, the U.S. Senate officially condemned his actions with a censure, ending his prospects for political leadership.
One particularly heinous aspect of the hunt for Communists in the United States, likened by playwright Arthur Miller to the witch hunts of old, was its effort to root out gay men and lesbians employed by the government. Many anti-Communists, including McCarthy, believed that gay men, referred to by Senator Everett Dirksen as “lavender lads,” were morally weak and thus were particularly likely to betray their country. Many also believed that lesbians and gay men were prone to being blackmailed by Soviet agents because of their sexual orientation, which at the time was regarded by psychiatrists as a form of mental illness.
### Section Summary
Joy at the ending of World War II was quickly replaced by fears of conflict with the Soviet Union. The Cold War heated up as both the United States and Soviet Union struggled for world dominance. Fearing Soviet expansion, the United States committed itself to assisting countries whose governments faced overthrow by Communist forces and gave billions of dollars to war-torn Europe to help it rebuild. While the United States achieved victory in its thwarting of Soviet attempts to cut Berlin off from the West, the nation was less successful in its attempts to prevent Communist expansion in Korea. The development of atomic weapons by the Soviet Union and the arrest of Soviet spies in the United States and Britain roused fears in the United States that Communist agents were seeking to destroy the nation from within. Loyalty board investigations and hearings before House and Senate committees attempted to root out Soviet sympathizers in the federal government and in other sectors of American society, including Hollywood and the military.
### Review Questions
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# Post-War Prosperity and Cold War Fears, 1945-1960
## The American Dream
Against the backdrop of the Cold War, Americans dedicated themselves to building a peaceful and prosperous society after the deprivation and instability of the Great Depression and World War II. Dwight D. Eisenhower, the general who led the United States to victory in Europe in 1945, proved to be the perfect president for the new era. Lacking strong conservative positions, he steered a middle path between conservatism and liberalism, and presided over a peacetime decade of economic growth and social conformity. In foreign affairs, Eisenhower’s New Look policy simultaneously expanded the nation’s nuclear arsenal and prevented the expansion of the defense budget for conventional forces.
### WE LIKE IKE
After Harry Truman declined to run again for the presidency, the election of 1952 emerged as a contest between the Democratic nominee, Illinois governor Adlai Stevenson, and Republican Dwight D. Eisenhower, who had directed American forces in Europe during World War II (). Eisenhower campaigned largely on a promise to end the war in Korea, a conflict the public had grown weary of fighting. He also vowed to fight Communism both at home and abroad, a commitment he demonstrated by choosing as his running mate Richard M. Nixon, a congressman who had made a name for himself by pursuing Communists, notably former State Department employee and suspected Soviet agent Alger Hiss.
In 1952, Eisenhower supporters enthusiastically proclaimed “We Like Ike,” and Eisenhower defeated Stevenson by winning 54 percent of the popular vote and 87 percent of the electoral vote (). When he assumed office in 1953, Eisenhower employed a leadership style he had developed during his years of military service. He was calm and willing to delegate authority regarding domestic affairs to his cabinet members, allowing him to focus his own efforts on foreign policy. Unlike many earlier presidents, such as Harry Truman, Eisenhower was largely nonpartisan and consistently sought a middle ground between liberalism and conservatism. He strove to balance the federal budget, which appealed to conservative Republicans, but retained much of the New Deal and even expanded Social Security. He maintained high levels of defense spending but, in his farewell speech in 1961, warned about the growth of the military-industrial complex, the matrix of relationships between officials in the Department of Defense and executives in the defense industry who all benefited from increases in defense spending. He disliked the tactics of Joseph McCarthy but did not oppose him directly, preferring to remain above the fray. He saw himself as a leader called upon to do his best for his country, not as a politician engaged in a contest for advantage over rivals.
In keeping with his goal of a balanced budget, Eisenhower switched the emphasis in defense from larger conventional forces to greater stockpiles of nuclear weapons. His New Look strategy embraced nuclear “massive retaliation,” a plan for nuclear response to a first Soviet strike so devastating that the attackers would not be able to respond. Some labeled this approach “Mutually Assured Destruction” or MAD.
Part of preparing for a possible war with the Soviet Union was informing the American public what to do in the event of a nuclear attack. The government provided instructions for building and equipping bomb shelters in the basement or backyard, and some cities constructed municipal shelters. Schools purchased dog tags to help identify students in the aftermath of an attack and showed children instructional films telling them what to do if atomic bombs were dropped on the city where they lived.
Government and industry allocated enormous amounts of money to the research and development of more powerful weapons. This investment generated rapid strides in missile technology as well as increasingly sensitive radar. Computers that could react more quickly than humans and thereby shoot down speeding missiles were also investigated. Many scientists on both sides of the Cold War, including captured Germans such as rocket engineer Werner von Braun, worked on these devices. An early success for the West came in 1950, when Alan Turing, a British mathematician who had broken Germany’s Enigma code during World War II, created a machine that mimicked human thought. His discoveries led scientists to consider the possibility of developing true artificial intelligence.
However, the United States often feared that the Soviets were making greater strides in developing technology with potential military applications. This was especially true following the Soviet Union’s launch of (), the first manmade satellite, in October 1957. In September 1958, Congress passed the National Defense Education Act, which pumped over $775 million into educational programs over four years, especially those programs that focused on math and science. Congressional appropriations to the National Science Foundation also increased by $100 million in a single year, from $34 million in 1958 to $134 million in 1959. One consequence of this increased funding was the growth of science and engineering programs at American universities.
In the diplomatic sphere, Eisenhower pushed Secretary of State John Foster Dulles to take a firmer stance against the Soviets to reassure European allies of continued American support. At the same time, keenly sensing that the stalemate in Korea had cost Truman his popularity, Eisenhower worked to avoid being drawn into foreign wars. Thus, when the French found themselves fighting Vietnamese Communists for control of France’s former colony of Indochina, Eisenhower provided money but not troops. Likewise, the United States took no steps when Hungary attempted to break away from Soviet domination in 1956. The United States also refused to be drawn in when Great Britain, France, and Israel invaded the Suez Canal Zone following Egypt’s nationalization of the canal in 1956. Indeed, Eisenhower, wishing to avoid conflict with the Soviet Union, threatened to impose economic sanctions on the invading countries if they did not withdraw.
### SUBURBANIZATION
Although the Eisenhower years were marked by fear of the Soviet Union and its military might, they were also a time of peace and prosperity. Even as many Americans remained mired in poverty, many others with limited economic opportunities, like African Americans or union workers, were better off financially in the 1950s and rose into the ranks of the middle class. Wishing to build the secure life that the Great Depression had deprived their parents of, young men and women married in record numbers and purchased homes where they could start families of their own. In 1940, the rate of homeownership in the United States was 43.6 percent. By 1960, it was almost 62 percent. Many of these newly purchased homes had been built in the new suburban areas that began to encircle American cities after the war. Although middle-class families had begun to move to the suburbs beginning in the nineteenth century, suburban growth accelerated rapidly after World War II.
Several factors contributed to this development. During World War II, the United States had suffered from a housing shortage, especially in cities with shipyards or large defense plants. Now that the war was over, real estate developers and contractors rushed to alleviate the scarcity. Unused land on the fringes of American cities provided the perfect place for new housing, which attracted not only the middle class, which had long sought homes outside the crowded cities, but also blue-collar workers who took advantage of the low-interest mortgages offered by the GI Bill.
An additional factor was the use of prefabricated construction techniques pioneered during World War II, which allowed houses complete with plumbing, electrical wiring, and appliances to be built and painted in a day. Employing these methods, developers built acres of inexpensive tract housing throughout the country. One of the first developers to take advantage of this method was William Levitt, who purchased farmland in Nassau County, Long Island, in 1947 and built thousands of prefabricated houses. The new community was named Levittown.
Levitt’s houses cost only $8,000 and could be bought with little or no down payment. The first day they were offered for sale, more than one thousand were purchased. Levitt went on to build similar developments, also called Levittown, in New Jersey and Pennsylvania (). As developers around the country rushed to emulate him, the name Levittown became synonymous with suburban tract housing, in which entire neighborhoods were built to either a single plan or a mere handful of designs. The houses were so similar that workers told of coming home late at night and walking into the wrong one. Levittown homes were similar in other ways as well; most were owned by White families. Levitt used restrictive language in his agreements with potential homeowners to ensure that only White people would live in his communities.
In the decade between 1950 and 1960, the suburbs grew by 46 percent. The transition from urban to suburban life exerted profound effects on both the economy and society. For example, fifteen of the largest U.S. cities saw their tax bases shrink significantly in the postwar period, and the apportionment of seats in the House of Representatives shifted to the suburbs and away from urban areas.
The development of the suburbs also increased reliance on the automobile for transportation. Suburban men drove to work in nearby cities or, when possible, were driven to commuter rail stations by their wives. In the early years of suburban development, before schools, parks, and supermarkets were built, access to an automobile was crucial, and the pressure on families to purchase a second one was strong. As families rushed to purchase them, the annual production of passenger cars leaped from 2.2 million to 8 million between 1946 and 1955, and by 1960, about 20 percent of suburban families owned two cars. The growing number of cars on the road changed consumption patterns, and drive-in and drive-through convenience stores, restaurants, and movie theaters began to dot the landscape. The first McDonalds opened in San Bernardino, California, in 1954 to cater to drivers in a hurry.
As drivers jammed highways and small streets in record numbers, cities and states rushed to build additional roadways and ease congestion. To help finance these massive construction efforts, states began taxing gasoline, and the federal government provided hundreds of thousands of dollars for the construction of the interstate highway system (). The resulting construction projects, designed to make it easier for suburbanites to commute to and from cities, often destroyed urban working-class neighborhoods. Increased funding for highway construction also left less money for public transportation, making it impossible for those who could not afford automobiles to live in the suburbs.
### THE ORGANIZATION MAN
As the government poured money into the defense industry and into universities that conducted research for the government, the economy boomed. The construction and automobile industries employed thousands, as did the industries they relied upon: steel, oil and gasoline refining, rubber, and lumber. As people moved into new homes, their purchases of appliances, carpeting, furniture, and home decorations spurred growth in other industries. The building of miles of roads also employed thousands. Unemployment was low, and wages for members of both the working and middle classes were high.
Following World War II, the majority of White Americans were members of the middle class, based on such criteria as education, income, and home ownership. Even most blue-collar families could afford such elements of a middle-class lifestyle as new cars, suburban homes, and regular vacations. Most African Americans, however, were not members of the middle class. In 1950, the median income for White families was $20,656, whereas for Black families it was $11,203. By 1960, when the average White family earned $28,485 a year, Black people still lagged behind at $15,786; nevertheless, this represented a more than 40 percent increase in African American income in the space of a decade.
While working-class men found jobs in factories and on construction crews, those in the middle class often worked for corporations that, as a result of government spending, had grown substantially during World War II and were still getting larger. Such corporations, far too large to allow managers to form personal relationships with all of their subordinates, valued conformity to company rules and standards above all else. In his best-selling book The Organization Man, however, William H. Whyte criticized the notion that conformity was the best path to success and self-fulfillment.
Conformity was still the watchword of suburban life: Many neighborhoods had rules mandating what types of clotheslines could be used and prohibited residents from parking their cars on the street. Above all, conforming to societal norms meant marrying young and having children. In the post-World War II period, marriage rates rose; the average age at first marriage dropped to twenty-three for men and twenty for women. Between 1946 and 1964, married couples also gave birth to the largest generation in U.S. history to date; this baby boom resulted in the cohort known as the baby boomers. Conformity also required that the wives of both working- and middle-class men stay home and raise children instead of working for wages outside the home. Most conformed to this norm, at least while their children were young. Nevertheless, 40 percent of women with young children and half of women with older children sought at least part-time employment. They did so partly out of necessity and partly to pay for the new elements of “the good life”—second cars, vacations, and college education for their children.
The children born during the baby boom were members of a more privileged generation than their parents had been. Entire industries sprang up to cater to their need for clothing, toys, games, books, and breakfast cereals. For the first time in U.S. history, attending high school was an experience shared by the majority, regardless of race or region. As the baby boomers grew into adolescence, marketers realized that they not only controlled large amounts of disposable income earned at part-time jobs, but they exerted a great deal of influence over their parents’ purchases as well. Madison Avenue began to appeal to teenage interests. Boys yearned for cars, and girls of all ethnicities wanted boyfriends who had them. New fashion magazines for adolescent girls, such as Seventeen, advertised the latest clothing and cosmetics, and teen romance magazines, like Copper Romance, a publication for young African American women, filled drugstore racks. The music and movie industries also altered their products to appeal to affluent adolescents who were growing tired of parental constraints.
### Section Summary
In 1953, Dwight D. Eisenhower became president of the United States. Fiscally conservative but ideologically moderate, he sought to balance the budget while building a strong system of national defense. This defense policy led to a greater emphasis on the possible use of nuclear weapons in any confrontation with the Soviet Union. Committed to maintaining peace, however, Eisenhower avoided engaging the United States in foreign conflicts; during his presidency, the economy boomed. Young Americans married in record numbers, moved to the growing suburbs, and gave birth to the largest generation to date in U.S. history. As middle-class adults, they conformed to the requirements of corporate jobs and suburban life, while their privileged children enjoyed a consumer culture tailored to their desires.
### Review Questions
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# Post-War Prosperity and Cold War Fears, 1945-1960
## Popular Culture and Mass Media
With a greater generational consciousness than previous generations, the baby boomers sought to define and redefine their identities in numerous ways. Music, especially rock and roll, reflected their desire to rebel against adult authority. Other forms of popular culture, such as movies and television, sought to entertain, while reinforcing values such as religious faith, patriotism, and conformity to societal norms.
### ROCKING AROUND THE CLOCK
In the 1940s, various evolutions of uptempo blues, jazz, and country music gave way to Rhythm and Blues, a genre predominantly created by Black artists and marketed to Black audiences. Sister Rosetta Tharpe was widely credited with delivering the first true Rock and Roll performance with "Strange Things Happening Everyday," and was a major influence on artists of the time. Several years later, Jackie Brantson, singing with Ike Turner's Band, released "Rocket 88," which became a chart-topper and is another contender for "first Rock and Roll recording." Aided by new technologies such as the "45" (or single record), the jukebox, and the solid-body electric guitar, R&B and Rock and Roll artists soon gained the attention and purchasing power of young White people. Rock and roll music celebrated themes such as young love and freedom from the oppression of middle-class society. It quickly grew in favor among American teens, thanks largely to the efforts of disc jockey Alan Freed, who named and popularized the music by playing it on the radio in Cleveland, where he also organized the first rock and roll concert, and later in New York.
The theme of rebellion against authority, present in many rock and roll songs, appealed to teens. White artists began covering popular songs by Black artists, and following in their footsteps. In 1954, Bill Haley and His Comets provided youth with an anthem for their rebellion—”Rock Around the Clock” (). The song, used in the 1955 movie Blackboard Jungle about a White teacher at a troubled inner-city high school, seemed to be calling for teens to declare their independence from adult control.
Haley illustrated how White artists could take musical motifs from the African American community and achieve mainstream success. Teen heartthrob Elvis Presley rose to stardom doing the same. Thus, besides encouraging a feeling of youthful rebellion, rock and roll also began to tear down color barriers, as White youths sought out African American musicians such as Chuck Berry and Little Richard ().
While youth had found an outlet for their feelings and concerns, parents were much less enthused about rock and roll and the values it seemed to promote. Many regarded the music as a threat to American values. When Elvis Presley appeared on The Ed Sullivan Show, a popular television variety program, the camera deliberately focused on his torso and did not show his swiveling hips or legs shaking in time to the music. Despite adults’ dislike of the genre, or perhaps because of it, more than 68 percent of the music played on the radio in 1956 was rock and roll.
### HOLLYWOOD ON THE DEFENSIVE
At first, Hollywood encountered difficulties in adjusting to the post-World War II environment. Although domestic audiences reached a record high in 1946 and the war’s end meant expanding international markets too, the groundwork for the eventual dismantling of the traditional studio system was laid in 1948, with a landmark decision by the U.S. Supreme Court. Previously, film studios had owned their own movie theater chains in which they exhibited the films they produced; however, in United States v. Paramount Pictures, Inc., this vertical integration of the industry—the complete control by one firm of the production, distribution, and exhibition of motion pictures—was deemed a violation of antitrust laws.
The HUAC hearings also targeted Hollywood. When eleven “unfriendly witnesses” were called to testify before Congress about Communism in the film industry in October 1947, only playwright Bertolt Brecht answered questions. The other ten, who refused to testify, were cited for contempt of Congress on November 24. The next day, film executives declared that the so-called “Hollywood Ten” would no longer be employed in the industry until they had sworn they were not Communists (). Eventually, more than three hundred actors, screenwriters, directors, musicians, and other entertainment professionals were placed on the industry blacklist. Some never worked in Hollywood again; others directed films or wrote screenplays under assumed names.
Hollywood reacted aggressively to these various challenges. Filmmakers tried new techniques, like CinemaScope and Cinerama, which allowed movies to be shown on large screens and in 3-D. Audiences were drawn to movies not because of gimmicks, however, but because of the stories they told. Dramas and romantic comedies continued to be popular fare for adults, and, to appeal to teens, studios produced large numbers of horror films and movies starring music idols such as Elvis. Many films took espionage, a timely topic, as their subject matter, and science fiction hits such as Invasion of the Body Snatchers, about a small town whose inhabitants fall prey to space aliens, played on audience fears of both Communist invasion and nuclear technology.
### THE TRIUMPH OF TELEVISION
By far the greatest challenge to Hollywood, however, came from the relatively new medium of television. Although the technology had been developed in the late 1920s, through much of the 1940s, only a fairly small audience of the wealthy had access to it. As a result, programming was limited. With the post-World War II economic boom, all this changed. In 1950, there were just under 4 million households with a television set, or 9 percent of all U.S. households. Five years later, that number had grown to over 30 million, or nearly 65 percent of all U.S. households ().
Various types of programs were broadcast on the handful of major networks: situation comedies, variety programs, game shows, soap operas, talk shows, medical dramas, adventure series, cartoons, and police procedurals. Many comedies presented an idealized image of White suburban family life: Happy housewife mothers, wise fathers, and mischievous but not dangerously rebellious children were constants on shows like Leave It to Beaver and Father Knows Best in the late 1950s. These shows also reinforced certain perspectives on the values of individualism and family—values that came to be redefined as “American” in opposition to alleged Communist collectivism. Westerns, which stressed unity in the face of danger and the ability to survive in hostile environments, were popular too. Programming for children began to emerge with shows such as Captain Kangaroo, Romper Room, and The Mickey Mouse Club designed to appeal to members of the baby boom.
### Section Summary
Young Americans in the postwar period had more disposable income and enjoyed greater material comfort than their forebears. These factors allowed them to devote more time and money to leisure activities and the consumption of popular culture. Rock and roll, which drew from African American roots in the blues, embraced themes popular among teenagers, such as young love and rebellion against authority. At the same time, traditional forms of entertainment, such as motion pictures, came under increasing competition from a relatively new technology, television.
### Review Questions
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# Post-War Prosperity and Cold War Fears, 1945-1960
## The African American Struggle for Civil Rights
In the aftermath of World War II, African Americans began to mount organized resistance to racially discriminatory policies in force throughout much of the United States. In the South, they used a combination of legal challenges and grassroots activism to begin dismantling the racial segregation that had stood for nearly a century following the end of Reconstruction. Community activists and civil rights leaders targeted racially discriminatory housing practices, segregated transportation, and legal requirements that African Americans and White people be educated separately. While many of these challenges were successful, life did not necessarily improve for African Americans. Hostile White people fought these changes in any way they could, including by resorting to violence.
### EARLY VICTORIES
During World War II, many African Americans had supported the “Double V Campaign,” which called on them to defeat foreign enemies while simultaneously fighting against segregation and discrimination at home. After World War II ended, many returned home to discover that, despite their sacrifices, the United States was not willing to extend them any greater rights than they had enjoyed before the war. Particularly rankling was the fact that although African American veterans were legally entitled to draw benefits under the GI Bill, discriminatory practices prevented them from doing so. For example, many banks would not give them mortgages if they wished to buy homes in predominantly African American neighborhoods, which banks often considered too risky an investment. However, African Americans who attempted to purchase homes in White neighborhoods often found themselves unable to do so because of real estate covenants that prevented owners from selling their property to Black people. Indeed, when a Black family purchased a Levittown house in 1957, they were subjected to harassment and threats of violence.
The postwar era, however, saw African Americans make greater use of the courts to defend their rights. In 1944, an African American woman, Irene Morgan, was arrested in Virginia for refusing to give up her seat on an interstate bus and sued to have her conviction overturned. In Morgan v. the Commonwealth of Virginia in 1946, the U.S. Supreme Court ruled that the conviction should be overturned because it violated the interstate commerce clause of the Constitution. This victory emboldened some civil rights activists to launch the Journey of Reconciliation, a bus trip taken by eight African American men and eight White men through the states of the Upper South to test the South’s enforcement of the Morgan decision.
Other victories followed. In 1948, in Shelley v. Kraemer, the U.S. Supreme Court held that courts could not enforce real estate covenants that restricted the purchase or sale of property based on race. In 1950, the NAACP brought a case before the U.S. Supreme Court that they hoped would help to undermine the concept of “separate but equal” as espoused in the 1896 decision in Plessy v. Ferguson, which gave legal sanction to segregated school systems. Sweatt v. Painter was a case brought by Heman Marion Sweatt, who sued the University of Texas for denying him admission to its law school because state law prohibited integrated education. Texas attempted to form a separate law school for African Americans only, but in its decision on the case, the U.S. Supreme Court rejected this solution, holding that the separate school provided neither equal facilities nor “intangibles,” such as the ability to form relationships with other future lawyers, that a professional school should provide.
Not all efforts to enact desegregation required the use of the courts, however. On April 15, 1947, Jackie Robinson started for the Brooklyn Dodgers, playing first base. He was the first African American to play baseball in the National League, breaking the color barrier. Although African Americans had their own baseball teams in the Negro Leagues, Robinson opened the gates for them to play in direct competition with White players in the major leagues. Other African American athletes also began to challenge the segregation of American sports. At the 1948 Summer Olympics, Alice Coachman, an African American, was the only American woman to take a gold medal in the games (). These changes, while symbolically significant, were mere cracks in the wall of segregation.
### DESEGREGATION AND INTEGRATION
Until 1954, racial segregation in education was not only legal but was required in seventeen states and permissible in several others (). Utilizing evidence provided in sociological studies conducted by Kenneth Clark and Gunnar Myrdal, however, Thurgood Marshall, then chief counsel for the NAACP, successfully argued the landmark case Brown v. Board of Education of Topeka, Kansas before the U.S. Supreme Court led by Chief Justice Earl Warren. Marshall showed that the practice of segregation in public schools made African American students feel inferior. Even if the facilities provided were equal in nature, the Court noted in its decision, the very fact that some students were separated from others on the basis of their race made segregation unconstitutional.
Plessy v. Fergusson had been overturned. The challenge now was to integrate schools. A year later, the U.S. Supreme Court ordered southern school systems to begin desegregation “with all deliberate speed.” Some school districts voluntarily integrated their schools. For many other districts, however, “deliberate speed” was very, very slow.
It soon became clear that enforcing Brown v. the Board of Education would require presidential intervention. Eisenhower did not agree with the U.S. Supreme Court’s decision and did not wish to force southern states to integrate their schools. However, as president, he was responsible for doing so. In 1957, Central High School in Little Rock, Arkansas, was forced to accept its first nine African American students, who became known as the Little Rock Nine. In response, Arkansas governor Orval Faubus called out the state National Guard to prevent the students from attending classes. The soldiers turned away the first student to attempt entry, Elizabeth Eckford, leaving the 15-year-old to be followed and threatened by dozens of White adults. A subsequent attempt by the nine students to attend school resulted in mob violence. Eisenhower then placed the Arkansas National Guard under federal control and sent the U.S. Army’s 101st airborne unit to escort the students to and from school as well as from class to class (). This was the first time since the end of Reconstruction that federal troops once more protected the rights of African Americans in the South.
Throughout the course of the school year, the Little Rock Nine were insulted, harassed, and physically assaulted; nevertheless, they returned to school each day. At the end of the school year, the first African American student graduated from Central High. At the beginning of the 1958–1959 school year, Orval Faubus ordered all Little Rock’s public schools closed. In the opinion of White segregationists, keeping all students out of school was preferable to having them attend integrated schools. In 1959, the U.S. Supreme Court ruled that the school had to be reopened and that the process of desegregation had to proceed.
School segregation was not only a Southern issue. New York City became a segregation flash point due to significant deficiencies in resources, teacher quality, and services offered to schools serving Black students. In 1957, parent and activist Mae Mallory was the leader of what became known as the Harlem Nine, a group of nine mothers who filed suit and kept their children out of school based on inadequate and unequal education. Mallory and the other mothers asked for an “open transfer” policy that allowed them to send their children to schools outside of their district. City officials and local media fought back by declaring Mallory and her group to be unfit parents, but the Harlem Nine eventually won the right to transfer their children. Most importantly, they forced the local court and the New York City Board of Education to declare that segregation still existed in New York City schools.
### WHITE RESPONSES
Efforts to desegregate public schools led to a backlash among many White people. Many greeted the Brown decision with horror; some World War II veterans questioned how the government they had fought for could betray them in such a fashion. Some White parents promptly withdrew their children from public schools and enrolled them in all-White private academies, many newly created for the sole purpose of keeping White children from attending integrated schools. Often, these “academies” held classes in neighbors’ basements or living rooms.
Other White southerners turned to state legislatures or courts to solve the problem of school integration. Orders to integrate school districts were routinely challenged in court. When the lawsuits proved unsuccessful, many southern school districts responded by closing all public schools, as Orval Faubus had done after Central High School was integrated. One county in Virginia closed its public schools for five years rather than see them integrated. Besides suing school districts, many southern segregationists filed lawsuits against the NAACP, trying to bankrupt the organization. Many national politicians supported the segregationist efforts. In 1956, 101 members of Congress signed “The Southern Manifesto,” in which they accused the U.S. Supreme Court of misusing its power and violating the principle of states’ rights, which maintained that states had rights equal to those of the federal government.
Unfortunately, many White southern racists, frightened by challenges to the social order, responded with violence. When Little Rock’s Central High School desegregated, an irate Ku Klux Klansman from a neighboring community sent a letter to the members of the city’s school board in which he denounced them as Communists and threatened to kill them. White rage sometimes erupted into murder. In August 1955, both White and Black Americans were shocked by the brutality of the murder of Emmett Till. Till, a fourteen-year-old boy from Chicago, had been vacationing with relatives in Mississippi. While visiting a White-owned store, he had made a remark to the White woman behind the counter. A few days later, the husband and brother-in-law of the woman came to the home of Till’s relatives in the middle of the night and abducted the boy. Till’s beaten and mutilated body was found in a nearby river three days later. Till’s mother insisted on an open-casket funeral; she wished to use her son’s body to reveal the brutality of southern racism. The murder of a child who had been guilty of no more than a casual remark captured the nation’s attention, as did the acquittal of the two men who admitted killing him.
### THE MONTGOMERY BUS BOYCOTT
One of those inspired by Till’s death was Rosa Parks, an NAACP member from Montgomery, Alabama, who became the face of the 1955–1956 Montgomery Bus Boycott. City ordinances in Montgomery segregated the city’s buses, forcing African American passengers to ride in the back section. They had to enter through the rear of the bus, could not share seats with White passengers, and, if the front of the bus was full and a White passenger requested an African American’s seat, had to relinquish their place to the White rider. The bus company also refused to hire African American drivers even though most of the people who rode the buses were Black.
On December 1, 1955, Rosa Parks refused to give her seat to a White man, and the Montgomery police arrested her. After being bailed out of jail, she decided to fight the laws requiring segregation in court. To support her, the Women’s Political Council, a group of African American female activists, organized a boycott of Montgomery’s buses. News of the boycott spread through newspaper notices and by word of mouth; ministers rallied their congregations to support the Women’s Political Council. Their efforts were successful, and forty thousand African American riders did not take the bus on December 5, the first day of the boycott.
Other African American leaders within the city embraced the boycott and maintained it beyond December 5, Rosa Parks’ court date. Among them was a young minister named Martin Luther King, Jr. For the next year, Black Montgomery residents avoided the city’s buses. Some organized carpools. Others paid for rides in African American-owned taxis, whose drivers reduced their fees. Most walked to and from school, work, and church for 381 days, the duration of the boycott. In June 1956, an Alabama federal court found the segregation ordinance unconstitutional. The city appealed, but the U.S. Supreme Court upheld the decision. The city’s buses were desegregated.
### Section Summary
After World War II, African American efforts to secure greater civil rights increased across the United States. African American lawyers such as Thurgood Marshall championed cases intended to destroy the Jim Crow system of segregation that had dominated the American South since Reconstruction. The landmark Supreme Court case Brown v. Board of Education prohibited segregation in public schools, but not all school districts integrated willingly, and President Eisenhower had to use the military to desegregate Little Rock’s Central High School. The courts and the federal government did not assist African Americans in asserting their rights in other cases. In Montgomery, Alabama, it was the grassroots efforts of African American citizens who boycotted the city’s bus system that brought about change. Throughout the region, many White southerners made their opposition to these efforts known. Too often, this opposition manifested itself in violence and tragedy, as in the murder of Emmett Till.
### Review Questions
### Critical Thinking Questions
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# Contesting Futures: America in the 1960s
## Introduction
The 1960s was a decade of hope, change, and war that witnessed an important shift in American culture. Citizens from all walks of life sought to expand the meaning of the American promise. Their efforts helped unravel the national consensus and laid bare a far more fragmented society. As a result, men and women from all ethnic groups attempted to reform American society to make it more equitable. The United States also began to take unprecedented steps to exert what it believed to be a positive influence on the world. At the same time, the country’s role in Vietnam revealed the limits of military power and the contradictions of U.S. foreign policy. The posthumous portrait of John F. Kennedy () captures this mix of the era’s promise and defeat. His election encouraged many to work for a better future, for both the middle class and the marginalized. Kennedy’s running mate, Lyndon B. Johnson, also envisioned a country characterized by the social and economic freedoms established during the New Deal years. Kennedy’s assassination in 1963, and the assassinations five years later of Martin Luther King, Jr. and Robert F. Kennedy, made it dramatically clear that not all Americans shared this vision of a more inclusive democracy. |
# Contesting Futures: America in the 1960s
## The Kennedy Promise
In the 1950s, President Dwight D. Eisenhower presided over a United States that prized conformity over change. Although change naturally occurred, as it does in every era, it was slow and greeted warily. By the 1960s, however, the pace of change had quickened and its scope broadened, as restive and energetic waves of World War II veterans and baby boomers of both sexes and all ethnicities began to make their influence felt politically, economically, and culturally. No one symbolized the hopes and energies of the new decade more than John Fitzgerald Kennedy, the nation’s new, young, and seemingly healthful, president. Kennedy had emphasized the country’s aspirations and challenges as a “new frontier” when accepting his party’s nomination at the Democratic National Convention in Los Angeles, California.
### THE NEW FRONTIER
The son of Joseph P. Kennedy, a wealthy Boston business owner and former ambassador to Great Britain, John F. Kennedy graduated from Harvard University and went on to serve in the U.S. House of Representatives in 1946. Even though he was young and inexperienced, his reputation as a war hero who had saved the crew of his PT boat after it was destroyed by the Japanese helped him to win election over more seasoned candidates, as did his father’s fortune. In 1952, he was elected to the U.S. Senate for the first of two terms. For many, including Arthur M. Schlesinger, Jr., a historian and member of Kennedy’s administration, Kennedy represented a bright, shining future in which the United States would lead the way in solving the most daunting problems facing the world.
Kennedy’s popular reputation as a great politician undoubtedly owes much to the style and attitude he personified. He and his wife Jacqueline conveyed a sense of optimism and youthfulness. “Jackie” was an elegant first lady who wore designer dresses, served French food in the White House, and invited classical musicians to entertain at state functions. “Jack” Kennedy, or JFK, went sailing off the coast of his family’s Cape Cod estate and socialized with celebrities (). Few knew that behind Kennedy’s healthful and sporty image was a gravely ill man whose wartime injuries caused him daily agony.
Nowhere was Kennedy’s style more evident than in the first televised presidential debate held on September 23, 1960, between him and his Republican opponent Vice President Richard M. Nixon. Seventy million viewers watched the debate on television; millions more heard it on the radio. Radio listeners judged Nixon the winner, whereas those who watched the debate on television believed the more telegenic Kennedy made the better showing.
Kennedy did not appeal to all voters, however. Many feared that because he was Roman Catholic, his decisions would be influenced by the Pope. Even traditional Democratic supporters, like the head of the United Auto Workers, Walter Reuther, feared that a Catholic candidate would lose the support of Protestants. Many southern Democrats also disliked Kennedy because of his liberal position on civil rights. To shore up support for Kennedy in the South, Lyndon B. Johnson, the Protestant Texan who was Senate majority leader, was added to the Democratic ticket as the vice presidential candidate. In the end, Kennedy won the election by the closest margin since 1888, defeating Nixon with only 0.01 percent more of the record sixty-seven million votes cast. His victory in the Electoral College was greater: 303 electoral votes to Nixon’s 219. Kennedy’s win made him both the youngest man elected to the presidency and the first U.S. president born in the twentieth century.
Kennedy dedicated his inaugural address to the theme of a new future for the United States. “Ask not what your country can do for you; ask what you can do for your country,” he challenged his fellow Americans. His lofty goals ranged from fighting poverty to winning the space race against the Soviet Union with a moon landing. He assembled an administration of energetic people assured of their ability to shape the future. Dean Rusk was named secretary of state. Robert McNamara, the former president of Ford Motor Company, became secretary of defense. Kennedy appointed his younger brother Robert as attorney general, much to the chagrin of many who viewed the appointment as a blatant example of nepotism.
Kennedy’s domestic reform plans remained hampered, however, by his narrow victory and lack of support from members of his own party, especially southern Democrats. As a result, he remained hesitant to propose new civil rights legislation. His achievements came primarily in poverty relief and care for the disabled. Unemployment benefits were expanded, the food stamps program was piloted, and the school lunch program was extended to more students. In October 1963, the passage of the Mental Retardation Facilities and Community Mental Health Centers Construction Act increased support for public mental health services.
### KENNEDY THE COLD WARRIOR
Kennedy focused most of his energies on foreign policy, an arena in which he had been interested since his college years and in which, like all presidents, he was less constrained by the dictates of Congress. Kennedy, who had promised in his inaugural address to protect the interests of the “free world,” engaged in Cold War politics on a variety of fronts. For example, in response to the lead that the Soviets had taken in the space race when Yuri Gagarin became the first human to successfully orbit the earth, Kennedy urged Congress to not only put a man into space () but also land an American on the moon, a goal finally accomplished in 1969. This investment advanced a variety of military technologies, especially the nation’s long-range missile capability, resulting in numerous profitable spin-offs for the aviation and communication industries. It also funded a growing middle class of government workers, engineers, and defense contractors in states ranging from California to Texas to Florida—a region that would come to be known as the Sun Belt—becoming a symbol of American technological superiority. At the same time, however, the use of massive federal resources for space technologies did not change the economic outlook for low-income communities and underprivileged regions.
To counter Soviet influence in the developing world, Kennedy supported a variety of measures. One of these was the Alliance for Progress, which collaborated with the governments of Latin American countries to promote economic growth and social stability in nations whose populations might find themselves drawn to communism. Kennedy also established the Agency for International Development to oversee the distribution of foreign aid, and he founded the Peace Corps, which recruited idealistic young people to undertake humanitarian projects in Asia, Africa, and Latin America. He hoped that by augmenting the food supply and improving healthcare and education, the U.S. government could encourage developing nations to align themselves with the United States and reject Soviet or Chinese overtures. The first group of Peace Corps volunteers departed for the four corners of the globe in 1961, serving as an instrument of “soft power” in the Cold War.
Kennedy’s various aid projects, like the Peace Corps, fit closely with his administration’s flexible response, which Robert McNamara advocated as a better alternative to the all-or-nothing defensive strategy of mutually assured destruction favored during Eisenhower’s presidency. The plan was to develop different strategies, tactics, and even military capabilities to respond more appropriately to small or medium-sized insurgencies, and political or diplomatic crises. One component of flexible response was the Green Berets, a U.S. Army Special Forces unit trained in counterinsurgency—the military suppression of rebel and nationalist groups in foreign nations. Much of the Kennedy administration’s new approach to defense, however, remained focused on the ability and willingness of the United States to wage both conventional and nuclear warfare, and Kennedy continued to call for increases in the American nuclear arsenal.
### Cuba
Kennedy’s multifaceted approach to national defense is exemplified by his careful handling of the Communist government of Fidel Castro in Cuba. In January 1959, following the overthrow of the corrupt and dictatorial regime of Fulgencio Batista, Castro assumed leadership of the new Cuban government. The progressive reforms he began indicated that he favored Communism, and his pro-Soviet foreign policy frightened the Eisenhower administration, which asked the Central Intelligence Agency (CIA) to find a way to remove him from power. Rather than have the U.S. military invade the small island nation, less than one hundred miles from Florida, and risk the world’s criticism, the CIA instead trained a small force of Cuban exiles for the job. After landing at the Bay of Pigs on the Cuban coast, these insurgents, the CIA believed, would inspire their countrymen to rise up and topple Castro’s regime. The United States also promised air support for the invasion.
Kennedy agreed to support the previous administration’s plans, and on April 17, 1961, approximately fourteen hundred Cuban exiles stormed ashore at the designated spot. However, Kennedy feared domestic criticism and worried about Soviet retaliation elsewhere in the world, such as Berlin. He cancelled the anticipated air support, which enabled the Cuban army to easily defeat the insurgents. The hoped-for uprising of the Cuban people also failed to occur. The surviving members of the exile army were taken into custody.
The Bay of Pigs invasion was a major foreign policy disaster for President Kennedy. The event highlighted how difficult it would be for the United States to act against the Castro administration. The following year, the Soviet Union sent troops and technicians to Cuba to strengthen its new ally against further U.S. military plots. Then, on October 14, U.S. spy planes took aerial photographs that confirmed the presence of long-range ballistic missile sites in Cuba. The United States was now within easy reach of Soviet nuclear warheads ().
On October 22, Kennedy demanded that Soviet premier Nikita Khrushchev remove the missiles. He also ordered a naval quarantine placed around Cuba to prevent Soviet ships from approaching. Despite his use of the word “quarantine” instead of “blockade,” for a blockade was considered an act of war, a potential war with the Soviet Union was nevertheless on the president’s mind. As U.S. ships headed for Cuba, the army was told to prepare for war, and Kennedy appeared on national television to declare his intention to defend the Western Hemisphere from Soviet aggression.
The world held its breath awaiting the Soviet reply. Realizing how serious the United States was, Khrushchev sought a peaceful solution to the crisis, overruling those in his government who urged a harder stance. Behind the scenes, Robert Kennedy and Soviet ambassador Anatoly Dobrynin worked toward a compromise that would allow both superpowers to back down without either side’s seeming intimidated by the other. On October 26, Khrushchev agreed to remove the Russian missiles in exchange for Kennedy’s promise not to invade Cuba. On October 27, Kennedy’s agreement was made public, and the crisis ended. Not made public, but nevertheless part of the agreement, was Kennedy’s promise to remove U.S. warheads from Turkey, as close to Soviet targets as the Cuban missiles had been to American ones.
The showdown between the United States and the Soviet Union over Cuba’s missiles had put the world on the brink of a nuclear war. Both sides already had long-range bombers with nuclear weapons airborne or ready for launch, and were only hours away from the first strike. In the long run, this nearly catastrophic example of nuclear brinksmanship ended up making the world safer. A telephone “hot line” was installed, linking Washington and Moscow to avert future crises, and in 1963, Kennedy and Khrushchev signed the Limited Test Ban Treaty, prohibiting tests of nuclear weapons in Earth’s atmosphere.
### Vietnam
Cuba was not the only arena in which the United States sought to contain the advance of Communism. In Indochina, nationalist independence movements, most notably Vietnam’s Viet Minh under the leadership of Ho Chi Minh, had strong Communist sympathies. President Harry S. Truman had no love for France’s colonial regime in Southeast Asia but did not want to risk the loyalty of its Western European ally against the Soviet Union. In 1950, the Truman administration sent a small military advisory group to Vietnam and provided financial aid to help France defeat the Viet Minh.
In 1954, Vietnamese forces finally defeated the French, and the country was temporarily divided at the seventeenth parallel. Ho Chi Minh and the Viet Minh controlled the North. In the South, the last Vietnamese emperor and ally to France, Bao Dai, named the French-educated, anti-Communist Ngo Dinh Diem as his prime minister. But Diem refused to abide by the Geneva Accords, the treaty ending the conflict that called for countrywide national elections in 1956, with the victor to rule a reunified nation. After a fraudulent election in the South in 1955, he ousted Bao Dai and proclaimed himself president of the Republic of Vietnam. He cancelled the 1956 elections in the South and began to round up Communists and supporters of Ho Chi Minh.
Realizing that Diem would never agree to the reunification of the country under Ho Chi Minh’s leadership, the North Vietnamese began efforts to overthrow the government of the South by encouraging insurgents to attack South Vietnamese officials. By 1960, North Vietnam had also created the National Liberation Front (NLF) to resist Diem and carry out an insurgency in the South. The United States, fearing the spread of Communism under Ho Chi Minh, supported Diem, assuming he would create a democratic, pro-Western government in South Vietnam. However, Diem’s oppressive and corrupt government made him a very unpopular ruler, particularly with farmers, students, and Buddhists, and many in the South actively assisted the NLF and North Vietnam in trying to overthrow his government.
When Kennedy took office, Diem’s government was faltering. Continuing the policies of the Eisenhower administration, Kennedy supplied Diem with money and military advisors to prop up his government (). By November 1963, there were sixteen thousand U.S. troops in Vietnam, training members of that country’s special forces and flying air missions that dumped defoliant chemicals on the countryside to expose North Vietnamese and NLF forces and supply routes. A few weeks before Kennedy’s own death, Diem and his brother Nhu were assassinated by South Vietnamese military officers after U.S. officials had indicated their support for a new regime.
### TENTATIVE STEPS TOWARD CIVIL RIGHTS
Cold War concerns, which guided U.S. policy in Cuba and Vietnam, also motivated the Kennedy administration’s steps toward racial equality. Realizing that legal segregation and widespread discrimination hurt the country’s chances of gaining allies in Africa, Asia, and Latin America, the federal government increased efforts to secure the civil rights of African Americans in the 1960s. During his presidential campaign, Kennedy had intimated his support for civil rights, and his efforts to secure the release of civil rights leader Martin Luther King, Jr., who was arrested following a demonstration, won him the African American vote. Lacking widespread backing in Congress, however, and anxious not to offend White southerners, Kennedy was cautious in assisting African Americans in their fight for full citizenship rights.
His strongest focus was on securing the voting rights of African Americans. Kennedy feared the loss of support from southern White Democrats and the impact a struggle over civil rights could have on his foreign policy agenda as well as on his reelection in 1964. But he thought voter registration drives far preferable to the boycotts, sit-ins, and integration marches that had generated such intense global media coverage in previous years. Encouraged by Congress’s passage of the Civil Rights Act of 1960, which permitted federal courts to appoint referees to guarantee that qualified persons would be registered to vote, Kennedy focused on the passage of a constitutional amendment outlawing poll taxes, a tactic that southern states used to disenfranchise African American voters. Originally proposed by President Truman’s Committee on Civil Rights, the idea had been largely forgotten during Eisenhower’s time in office. Kennedy, however, revived it and convinced Spessard Holland, a conservative Florida senator, to introduce the proposed amendment in Congress. It passed both houses of Congress and was sent to the states for ratification in September 1962.
Kennedy also reacted to the demands of the civil rights movement for equality in education. For example, when African American student James Meredith, encouraged by Kennedy’s speeches, attempted to enroll at the segregated University of Mississippi in 1962, riots broke out on campus (). The president responded by sending the U.S. Army and National Guard to Oxford, Mississippi, to support the U.S. Marshals that his brother Robert, the attorney general, had dispatched.
Following similar violence at the University of Alabama when two African American students, Vivian Malone and James Hood, attempted to enroll in 1963, Kennedy responded with a bill that would give the federal government greater power to enforce school desegregation, prohibit segregation in public accommodations, and outlaw discrimination in employment. Kennedy would not live to see his bill enacted; it would become law during Lyndon Johnson’s administration as the 1964 Civil Rights Act.
### TRAGEDY IN DALLAS
Although his stance on civil rights had won him support in the African American community and his steely performance during the Cuban Missile Crisis had led his overall popularity to surge, Kennedy understood that he had to solidify his base in the South to secure his reelection. On November 21, 1963, he accompanied Lyndon Johnson to Texas to rally his supporters. The next day, shots rang out as Kennedy’s motorcade made its way through the streets of Dallas. Seriously injured, Kennedy was rushed to Parkland Hospital and pronounced dead.
The gunfire that killed Kennedy appeared to come from the upper stories of the Texas School Book Depository building; later that day, Lee Harvey Oswald, an employee at the depository and a trained sniper, was arrested (). Two days later, while being transferred from Dallas police headquarters to the county jail, Oswald was shot and killed by Jack Ruby, a local nightclub owner who claimed he acted to avenge the president.
Almost immediately, rumors began to circulate regarding the Kennedy assassination, and conspiracy theorists, pointing to the unlikely coincidence of Oswald’s murder a few days after Kennedy’s, began to propose alternate theories about the events. To quiet the rumors and allay fears that the government was hiding evidence, Lyndon Johnson, Kennedy’s successor, appointed a fact-finding commission headed by Earl Warren, chief justice of the U.S. Supreme Court, to examine all the evidence and render a verdict. The Warren Commission concluded that Lee Harvey Oswald had acted alone and there had been no conspiracy. The commission’s ruling failed to satisfy many, and multiple theories have sprung up over time. No credible evidence has ever been uncovered, however, to prove either that someone other than Oswald murdered Kennedy or that Oswald acted with co-conspirators.
### Section Summary
The arrival of the Kennedys in the White House seemed to signal a new age of youth, optimism, and confidence. Kennedy spoke of a “new frontier” and promoted the expansion of programs to aid the poor, protect African Americans’ right to vote, and improve African Americans’ employment and education opportunities. For the most part, however, Kennedy focused on foreign policy and countering the threat of Communism—especially in Cuba, where he successfully defused the Cuban Missile Crisis, and in Vietnam, to which he sent advisors and troops to support the South Vietnamese government. The tragedy of Kennedy’s assassination in Dallas brought an early end to the era, leaving Americans to wonder whether his vice president and successor, Lyndon Johnson, would bring Kennedy’s vision for the nation to fruition.
### Review Questions
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# Contesting Futures: America in the 1960s
## Lyndon Johnson and the Great Society
On November 27, 1963, a few days after taking the oath of office, President Johnson addressed a joint session of Congress and vowed to accomplish the goals that John F. Kennedy had set and to expand the role of the federal government in securing economic opportunity and civil rights for all. Johnson brought to his presidency a vision of a Great Society in which everyone could share in the opportunities for a better life that the United States offered, and in which the words “liberty and justice for all” would have real meaning.
### THE GREAT SOCIETY
In May 1964, in a speech at the University of Michigan, Lyndon Johnson described in detail his vision of the Great Society he planned to create (). When the Eighty-Ninth Congress convened the following January, he and his supporters began their effort to turn the promise into reality. By combatting racial discrimination and attempting to eliminate poverty, the reforms of the Johnson administration changed the nation.
One of the chief pieces of legislation that Congress passed in 1965 was the Elementary and Secondary Education Act (). Johnson, a former teacher, realized that a lack of education was the primary cause of poverty and other social problems. Educational reform was thus an important pillar of the society he hoped to build. This act provided increased federal funding to both elementary and secondary schools, allocating more than $1 billion for the purchase of books and library materials, and the creation of educational programs for disadvantaged children. The Higher Education Act, signed into law the same year, provided scholarships and low-interest loans for the poor, increased federal funding for colleges and universities, and created a corps of teachers to serve schools in impoverished areas.
Education was not the only area toward which Johnson directed his attention. Consumer protection laws were also passed that improved the safety of meat and poultry, placed warning labels on cigarette packages, required “truth in lending” by creditors, and set safety standards for motor vehicles. Funds were provided to improve public transportation and to fund high-speed mass transit. To protect the environment, the Johnson administration created laws protecting air and water quality, regulating the disposal of solid waste, preserving wilderness areas, and protecting endangered species. All of these laws fit within Johnson’s plan to make the United States a better place to live. Perhaps influenced by Kennedy’s commitment to the arts, Johnson also signed legislation creating the National Endowment for the Arts and the National Endowment for the Humanities, which provided funding for artists and scholars. The Public Broadcasting Act of 1967 authorized the creation of the private, not-for-profit Corporation for Public Broadcasting, which helped launch the Public Broadcasting Service (PBS) and National Public Radio (NPR) in 1970.
In 1965, the Johnson administration also encouraged Congress to pass the Immigration and Nationality Act, which essentially overturned legislation from the 1920s that had favored immigrants from western and northern Europe over those from eastern and southern Europe. The law lifted severe restrictions on immigration from Asia and gave preference to immigrants with family ties in the United States and immigrants with desirable skills. Although the measure seemed less significant than many of the other legislative victories of the Johnson administration at the time, it opened the door for a new era in immigration and made possible the formation of Asian and Latin American immigrant communities in the following decades.
While these laws touched on important aspects of the Great Society, the centerpiece of Johnson’s plan was the eradication of poverty in the United States. The war on poverty, as he termed it, was fought on many fronts. The 1965 Housing and Urban Development Act offered grants to improve city housing and subsidized rents for the poor. The Model Cities program likewise provided money for urban development projects and the building of public housing.
The Economic Opportunity Act (EOA) of 1964 established and funded a variety of programs to assist the poor in finding jobs. The Office of Economic Opportunity (OEO), first administered by President Kennedy’s brother-in-law Sargent Shriver, coordinated programs such as the Jobs Corps and the Neighborhood Youth Corps, which provided job training programs and work experience for the disadvantaged. Volunteers in Service to America recruited people to offer educational programs and other community services in poor areas, just as the Peace Corps did abroad. The Community Action Program, also under the OEO, funded local Community Action Agencies, organizations created and managed by residents of disadvantaged communities to improve their own lives and those of their neighbors. The Head Start program, intended to prepare low-income children for elementary school, was also under the OEO until it was transferred to Department of Health, Education, and Welfare in 1969.
The EOA fought rural poverty by providing low-interest loans to those wishing to improve their farms or start businesses (). EOA funds were also used to provide housing and education for migrant farm workers. Other legislation created jobs in Appalachia, one of the poorest regions in the United States, and brought programs to Indian reservations. One of EOA’s successes was the Rough Rock Demonstration School on the Navajo Reservation that, while respecting Navajo traditions and culture, also trained people for careers and jobs outside the reservation.
The Johnson administration, realizing the nation’s elderly were among its poorest and most disadvantaged citizens, passed the Social Security Act of 1965. The most profound change made by this act was the creation of Medicare, a program to pay the medical expenses of those over sixty-five. Although opposed by the American Medical Association, which feared the creation of a national healthcare system, the new program was supported by most citizens because it would benefit all social classes, not just the poor. The act and subsequent amendments to it also provided coverage for self-employed people in certain occupations and expanded the number of disabled who qualified for benefits. The following year, the Medicaid program allotted federal funds to pay for medical care for the poor.
### JOHNSON’S COMMITMENT TO CIVIL RIGHTS
The eradication of poverty was matched in importance by the Great Society’s advancement of civil rights. Indeed, the condition of the poor could not be alleviated if racial discrimination limited their access to jobs, education, and housing. Realizing this, Johnson drove the long-awaited civil rights act, proposed by Kennedy in June 1963 in the wake of riots at the University of Alabama, through Congress. Under Kennedy’s leadership, the bill had passed the House of Representatives but was stalled in the Senate by a filibuster. Johnson, a master politician, marshaled his considerable personal influence and memories of his fallen predecessor to break the filibuster. The Civil Rights Act of 1964, the most far-reaching civil rights act yet passed by Congress, banned discrimination in public accommodations, sought to aid schools in efforts to desegregate, and prohibited federal funding of programs that permitted racial segregation. Further, it barred discrimination in employment on the basis of race, color, national origin, religion, or gender, and established an Equal Employment Opportunity Commission.
Protecting African Americans’ right to vote was as important as ending racial inequality in the United States. In January 1964, the Twenty-Fourth Amendment, prohibiting the imposition of poll taxes on voters, was finally ratified. Poverty would no longer serve as an obstacle to voting. Other impediments remained, however. Attempts to register southern African American voters encountered White resistance, and protests against this interference often met with violence. On March 7, 1965, a planned protest march from Selma, Alabama, to the state capitol in Montgomery, turned into “Bloody Sunday” when marchers crossing the Edmund Pettus Bridge encountered a cordon of state police, wielding batons and tear gas (). Images of White brutality appeared on television screens throughout the nation and in newspapers around the world.
Deeply disturbed by the violence in Alabama and the refusal of Governor George Wallace to address it, Johnson introduced a bill in Congress that would remove obstacles for African American voters and lend federal support to their cause. His proposal, the Voting Rights Act of 1965, prohibited states and local governments from passing laws that discriminated against voters on the basis of race (). Literacy tests and other barriers to voting that had kept ethnic minorities from the polls were thus outlawed. Following the passage of the act, a quarter of a million African Americans registered to vote, and by 1967, the majority of African Americans had done so. Johnson’s final piece of civil rights legislation was the Civil Rights Act of 1968, which prohibited discrimination in housing on the basis of race, color, national origin, or religion.
### INCREASED COMMITMENT IN VIETNAM
Building the Great Society had been Lyndon Johnson’s biggest priority, and he effectively used his decades of experience in building legislative majorities in a style that ranged from diplomacy to quid pro quo deals to bullying. In the summer of 1964, he deployed these political skills to secure congressional approval for a new strategy in Vietnam—with fateful consequences.
President Johnson had never been the cold warrior Kennedy was, but believed that the credibility of the nation and his office depended on maintaining a foreign policy of containment. When, on August 2, the U.S. destroyer USS Maddox conducted an arguably provocative intelligence-gathering mission in the gulf of Tonkin, it reported an attack by North Vietnamese torpedo boats. Two days later, the Maddox was supposedly struck again, and a second ship, the USS Turner Joy, reported that it also had been fired upon. The North Vietnamese denied the second attack, and Johnson himself doubted the reliability of the crews’ report. The National Security Agency has since revealed that the August 4 attacks did not occur. Relying on information available at the time, however, Secretary of Defense Robert McNamara reported to Congress that U.S. ships had been fired upon in international waters while conducting routine operations. On August 7, with only two dissenting votes, Congress passed the Gulf of Tonkin Resolution, and on August 10, the president signed the resolution into law. The resolution gave President Johnson the authority to use military force in Vietnam without asking Congress for a declaration of war. It dramatically increased the power of the U.S. president and transformed the American role in Vietnam from advisor to combatant.
In 1965, large-scale U.S. bombing of North Vietnam began. The intent of the campaign, which lasted three years under various names, was to force the North to end its support for the insurgency in the South. More than 200,000 U.S. military personnel, including combat troops, were sent to South Vietnam. At first, most of the American public supported the president’s actions in Vietnam. Support began to ebb, however, as more troops were deployed. Frustrated by losses suffered by the South’s Army of the Republic of Vietnam (ARVN), General William Westmoreland called for the United States to take more responsibility for fighting the war. By April 1966, more Americans were being killed in battle than ARVN troops. Johnson, however, maintained that the war could be won if the United States stayed the course, and in November 1967, Westmoreland proclaimed the end was in sight.
Westmoreland’s predictions were called into question, however, when in January 1968, the North Vietnamese launched their most aggressive assault on the South, deploying close to eighty-five thousand troops. During the Tet Offensive, as these attacks were known, nearly one hundred cities in the South were attacked, including the capital of Saigon (). In heavy fighting, U.S. and South Vietnamese forces recaptured all the points taken by the enemy.
Although North Vietnamese forces suffered far more casualties than the roughly forty-one hundred U.S. soldiers killed, public opinion in the United States, fueled by graphic images provided in unprecedented media coverage, turned against the war. Disastrous surprise attacks like the Tet Offensive persuaded many that the war would not be over soon and raised doubts about whether Johnson’s administration was telling the truth about the real state of affairs. In May 1968, with over 400,000 U.S. soldiers in Vietnam, Johnson began peace talks with the North.
It was too late to save Johnson himself, however. Many of the most outspoken critics of the war were Democratic politicians whose opposition began to erode unity within the party. Minnesota senator Eugene McCarthy, who had called for an end to the war and the withdrawal of troops from Vietnam, received nearly as many votes in the New Hampshire presidential primary as Johnson did, even though he had been expected to fare very poorly. McCarthy’s success in New Hampshire encouraged Robert Kennedy to announce his candidacy as well. Johnson, suffering health problems and realizing his actions in Vietnam had hurt his public standing, announced that he would not seek reelection and withdrew from the 1968 presidential race.
### THE END OF THE GREAT SOCIETY
Perhaps the greatest casualty of the nation’s war in Vietnam was the Great Society. As the war escalated, the money spent to fund it also increased, leaving less to pay for the many social programs Johnson had created to lift Americans out of poverty. Johnson knew he could not achieve his Great Society while spending money to wage the war. He was unwilling to withdraw from Vietnam, however, for fear that the world would perceive this action as evidence of American failure and doubt the ability of the United States to carry out its responsibilities as a superpower.
Vietnam doomed the Great Society in other ways as well. Dreams of racial harmony suffered, as many African Americans, angered by the failure of Johnson’s programs to alleviate severe poverty in the inner cities, rioted in frustration. Their anger was heightened by the fact that a disproportionate number of African Americans were fighting and dying in Vietnam. Nearly two-thirds of eligible African Americans were drafted, whereas draft deferments for college, exemptions for skilled workers in the military industrial complex, and officer training programs allowed White middle-class youth to either avoid the draft or volunteer for a military branch of their choice. As a result, less than one-third of White men were drafted.
Although the Great Society failed to eliminate suffering or increase civil rights to the extent that Johnson wished, it made a significant difference in people’s lives. By the end of Johnson’s administration, the percentage of people living below the poverty line had been cut nearly in half. While more people of color than White people continued to live in poverty, the percentage of poor African Americans had decreased dramatically. The creation of Medicare and Medicaid as well as the expansion of Social Security benefits and welfare payments improved the lives of many, while increased federal funding for education enabled more people to attend college than ever before. Conservative critics argued that, by expanding the responsibilities of the federal government to care for the poor, Johnson had hurt both taxpayers and the poor themselves. Aid to the poor, many maintained, would not only fail to solve the problem of poverty but would also encourage people to become dependent on government “handouts” and lose their desire and ability to care for themselves—an argument that many found intuitively compelling but which lacked conclusive evidence. These same critics also accused Johnson of saddling the United States with a large debt as a result of the deficit spending (funded by borrowing) in which he had engaged.
### Section Summary
Lyndon Johnson began his administration with dreams of fulfilling his fallen predecessor’s civil rights initiative and accomplishing his own plans to improve lives by eradicating poverty in the United States. His social programs, investments in education, support for the arts, and commitment to civil rights changed the lives of countless people and transformed society in many ways. However, Johnson’s insistence on maintaining American commitments in Vietnam, a policy begun by his predecessors, hurt both his ability to realize his vision of the Great Society and his support among the American people.
### Review Questions
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# Contesting Futures: America in the 1960s
## The Civil Rights Movement Marches On
During the 1960s, the federal government, encouraged by both genuine concern for the dispossessed and the realities of the Cold War, had increased its efforts to protect civil rights and ensure equal economic and educational opportunities for all. However, most of the credit for progress toward racial equality in the Unites States lies with grassroots activists. Indeed, it was campaigns and demonstrations by ordinary people that spurred the federal government to action. Although the African American civil rights movement was the most prominent of the crusades for racial justice, other ethnic minorities also worked to seize their piece of the American dream during the promising years of the 1960s. Many were influenced by the African American cause and often used similar tactics.
### CHANGE FROM THE BOTTOM UP
For many people inspired by the victories of Brown v. Board of Education and the Montgomery Bus Boycott, the glacial pace of progress in the segregated South was frustrating if not intolerable. In some places, such as Greensboro, North Carolina, local NAACP chapters had been influenced by White people who provided financing for the organization. This aid, together with the belief that more forceful efforts at reform would only increase White resistance, had persuaded some African American organizations to pursue a “politics of moderation” instead of attempting to radically alter the status quo. Martin Luther King Jr.’s inspirational appeal for peaceful change in the city of Greensboro in 1958, however, planted the seed for a more assertive civil rights movement.
On February 1, 1960, four sophomores at the North Carolina Agricultural & Technical College in Greensboro—Ezell Blair, Jr., Joseph McNeil, David Richmond, and Franklin McCain—entered the local Woolworth’s and sat at the lunch counter. The lunch counter was segregated, and they were refused service as they knew they would be. They had specifically chosen Woolworth’s, because it was a national chain and was thus believed to be especially vulnerable to negative publicity. Over the next few days, more protesters joined the four sophomores. Hostile White people responded with threats and taunted the students by pouring sugar and ketchup on their heads. The successful six-month-long Greensboro sit-in initiated the student phase of the African American civil rights movement and, within two months, the sit-in movement had spread to fifty-four cities in nine states ().
In the words of grassroots civil rights activist Ella Baker, the students at Woolworth’s wanted more than a hamburger; the movement they helped launch was about empowerment. Baker had grown up listening to her grandmother's stories about life as an enslaved person, and had dedicated her life to racial justice. One of her main roles in both the NAACP and King's Southern Christian Leadership Conference (of which she was the first staff member) had been developing local branches and combining the efforts of diverse groups across states and ideologies. Her talent for organization and education laid the groundwork for city and state initiatives across the country, which proved critical in later efforts such as voting drives. Baker pushed for a “participatory Democracy” that built on the grassroots campaigns of active citizens instead of deferring to the leadership of educated elites and experts. As a result of her actions, in April 1960, the Student Nonviolent Coordinating Committee (SNCC) formed to carry the battle forward. Within a year, more than one hundred cities had desegregated at least some public accommodations in response to student-led demonstrations. The sit-ins inspired other forms of nonviolent protest intended to desegregate public spaces. “Sleep-ins” occupied motel lobbies, “read-ins” filled public libraries, and churches became the sites of “pray-ins.”
Students also took part in the 1961 “freedom rides” sponsored by the Congress of Racial Equality (CORE) and SNCC. The intent of the African American and White volunteers who undertook these bus rides south was to test enforcement of a U.S. Supreme Court decision prohibiting segregation on interstate transportation and to protest segregated waiting rooms in southern terminals. Departing Washington, DC, on May 4, the volunteers headed south on buses that challenged the seating order of Jim Crow segregation. White riders would stay in the back, African-Americans would sit in the front, and on other occasions, riders of different races would share the same bench seat. The Freedom Riders encountered little difficulty until they reached Rock Hill, South Carolina, where a mob severely beat John Lewis, a freedom rider who later became chairman of SNCC (). The danger increased as the riders continued through Georgia into Alabama, where one of the two buses was firebombed outside the town of Anniston. The second group continued to Birmingham, where the riders were attacked by the Ku Klux Klan as they attempted to disembark at the city bus station. The remaining volunteers continued to Mississippi, where they were arrested when they attempted to desegregate the waiting rooms in the Jackson bus terminal.
### FREE BY ’63 (OR ’64 OR ’65)
The grassroots efforts of people like the Freedom Riders to change discriminatory laws and longstanding racist traditions grew more widely known in the mid-1960s. The approaching centennial of Abraham Lincoln’s Emancipation Proclamation spawned the slogan “Free by ’63” among civil rights activists. As African Americans increased their calls for full rights for all Americans, many civil rights groups changed their tactics to reflect this new urgency.
In Cambridge, Maryland, hospital and school segregation led to severe health issues and limited educational advancement. The area's only two factories had declared that they would not hire Black people, and housing limitations led to horrible living situations. To bring about change, local activists Gloria Richardson and Inez Grubb launched the only affiliate of the SNCC that was not led by students, the Cambridge Nonviolent Action Committee (CNAC). They began protests against local businesses that refused to hire Black workers, and conducted sit-ins at restaurants and other venues that would not serve Black people. Mobs of White people disrupted these protests, often with violence, and the conditions escalated to the point where both groups regularly carried firearms. As riots ensued and martial law was declared, the U.S. Attorney General, Robert Kennedy, negotiated what became known as the Treaty of Cambridge, which would have guaranteed complete desegregation of schools, as well as provisions for public housing. After Kennedy's intervention, the local government began to pull back from the arrangement. While some of her colleagues considered a softer stance, Richardson warned against complacency: “A first-class citizen does not beg for freedom. A first-class citizen does not plead to the white power structure to give him something that the whites have no power to give or take away. Human rights are human rights, not white rights.”
Perhaps the most famous of the civil rights-era demonstrations was the March on Washington for Jobs and Freedom, held in August 1963, on the one hundredth anniversary of Abraham Lincoln’s Emancipation Proclamation. Its purpose was to pressure President Kennedy to act on his promises regarding civil rights. The date was the eighth anniversary of the brutal racist murder of fourteen-year-old Emmett Till in Money, Mississippi. As the crowd gathered outside the Lincoln Memorial and spilled across the National Mall (), Martin Luther King, Jr. delivered his most famous speech. In “I Have a Dream,” King called for an end to racial injustice in the United States and envisioned a harmonious, integrated society. The speech marked the high point of the civil rights movement and established the legitimacy of its goals. However, it did not prevent White terrorism in the South, nor did it permanently sustain the tactics of nonviolent civil disobedience.
Other gatherings of civil rights activists ended tragically, and some demonstrations were intended to provoke a hostile response from White people and thus reveal the inhumanity of the Jim Crow laws and their supporters. In 1963, the Southern Christian Leadership Conference (SCLC) led by Martin Luther King, Jr. mounted protests in some 186 cities throughout the South. The campaign in Birmingham that began in April and extended into the fall of 1963 attracted the most notice, however, when a peaceful protest was met with violence by police, who attacked demonstrators, including children, with fire hoses and dogs. The world looked on in horror as innocent people were assaulted and thousands arrested. King himself was jailed on Easter Sunday, 1963, and, in response to the pleas of White clergymen for peace and patience, he penned one of the most significant documents of the struggle—“Letter from a Birmingham Jail.” In the letter, King argued that African Americans had waited patiently for more than three hundred years to be given the rights that all human beings deserved; the time for waiting was over.
Some of the greatest violence during this era was aimed at those who attempted to register African Americans to vote. In 1964, SNCC, working with other civil rights groups, initiated its Mississippi Summer Project, also known as Freedom Summer. The purpose was to register African American voters in one of the most racist states in the nation. Volunteers also built “freedom schools” and community centers. SNCC invited hundreds of White middle-class students, mostly from the North, to help in the task. Many volunteers were harassed, beaten, and arrested, and African American homes and churches were burned. Three civil rights workers, James Chaney, Michael Schwerner, and Andrew Goodman, were killed by the Ku Klux Klan with the help of police. After the three men were released following a questionable arrest, a local deputy intercepted them and forced them into his car. He drove them into the hands of a group of Klan members, who beat and shot the men. That summer, civil rights activists Fannie Lou Hamer, Ella Baker, and Robert Parris Moses formally organized the Mississippi Freedom Democratic Party (MFDP) as an alternative to the all-White Mississippi Democratic Party. The Democratic National Convention’s organizers, however, would allow only two MFDP delegates to be seated, and they were confined to the roles of nonvoting observers.
The vision of White people and African Americans working together peacefully to end racial injustice suffered a severe blow with the death of Martin Luther King, Jr. in Memphis, Tennessee, in April 1968. King had gone there to support sanitation workers trying to unionize. In the city, he found a divided civil rights movement; older activists who supported his policy of nonviolence were being challenged by younger African Americans who advocated a more militant approach. On April 4, King was shot and killed while standing on the balcony of his motel. Within hours, the nation’s cities exploded with violence as angry African Americans, shocked by his murder, burned and looted inner-city neighborhoods across the country (). While White people recoiled from news about the riots in fear and dismay, they also criticized African Americans for destroying their own neighborhoods; they did not realize that most of the violence was directed against businesses that were not owned by Black people and that treated African American customers with suspicion and hostility.
### BLACK FRUSTRATION, BLACK POWER
The episodes of violence that accompanied Martin Luther King Jr.’s murder were but the latest in a string of urban riots that had shaken the United States since the mid-1960s. Between 1964 and 1968, there were 329 riots in 257 cities across the nation. In 1964, riots broke out in Harlem and other African American neighborhoods. In 1965, a traffic stop set in motion a chain of events that culminated in riots in Watts, an African American neighborhood in Los Angeles. Thousands of businesses were destroyed, and, by the time the violence ended, thirty-four people were dead, most of them African Americans killed by the Los Angeles police and the National Guard. More riots took place in 1966 and 1967.
Frustration and anger lay at the heart of these disruptions. Despite the programs of the Great Society, good healthcare, job opportunities, and safe housing were abysmally lacking in urban African American neighborhoods in cities throughout the country, including in the North and West, where discrimination was less overt but just as devastating. In the eyes of many rioters, the federal government either could not or would not end their suffering, and most existing civil rights groups and their leaders had been unable to achieve significant results toward racial justice and equality. Disillusioned, many African Americans turned to those with more radical ideas about how best to obtain equality and justice.
Within the chorus of voices calling for integration and legal equality were many that more stridently demanded empowerment and thus supported Black Power. Black Power meant a variety of things. One of the most famous users of the term was Stokely Carmichael, the chairman of SNCC, who later changed his name to Kwame Ture. For Carmichael, Black Power was the power of African Americans to unite as a political force and create their own institutions apart from White-dominated ones, an idea also espoused in the 1920s by political leader and orator Marcus Garvey. Like Garvey, Carmichael became an advocate of Black separatism, arguing that African Americans should live apart from White people and solve their problems for themselves. In keeping with this philosophy, Carmichael expelled SNCC’s White members. He left SNCC in 1967 and later joined the Black Panthers (see below).
Long before Carmichael began to call for separatism, the Nation of Islam, founded in 1930, had advocated the same thing. In the 1960s, its most famous member was Malcolm X, born Malcolm Little (). The Nation of Islam advocated the separation of White Americans and African Americans because of a belief that African Americans could not thrive in an atmosphere of White racism. Indeed, in a 1963 interview, Malcolm X, discussing the teachings of the head of the Nation of Islam in America, Elijah Muhammad, referred to White people as “devils” more than a dozen times. Rejecting the nonviolent strategy of other civil rights activists, he maintained that violence in the face of violence was appropriate.
In 1964, after a trip to Africa, Malcolm X left the Nation of Islam to found the Organization of Afro-American Unity with the goal of achieving freedom, justice, and equality “by any means necessary.” His views regarding Black-White relations changed somewhat thereafter, but he remained fiercely committed to the cause of African American empowerment. On February 21, 1965, he was killed by members of the Nation of Islam. Stokely Carmichael later recalled that Malcolm X had provided an intellectual basis for Black Nationalism and given legitimacy to the use of violence in achieving the goals of Black Power.
Unlike Stokely Carmichael and the Nation of Islam, most Black Power advocates did not believe African Americans needed to separate themselves from White society. The Black Panther Party, founded in 1966 in Oakland, California, by Bobby Seale and Huey Newton, believed African Americans were as much the victims of capitalism as of White racism. Accordingly, the group espoused Marxist teachings, and called for jobs, housing, and education, as well as protection from police brutality and exemption from military service in their Ten Point Program. The Black Panthers also patrolled the streets of African American neighborhoods to protect residents from police brutality, yet sometimes beat and murdered those who did not agree with their cause and tactics. Their militant attitude and advocacy of armed self-defense attracted many young men but also led to many encounters with the police, which sometimes included arrests and even shootouts, such as those that took place in Los Angeles, Chicago and Carbondale, Illinois.
The self-empowerment philosophy of Black Power influenced mainstream civil rights groups such as the National Economic Growth Reconstruction Organization (NEGRO), which sold bonds and operated a clothing factory and construction company in New York, and the Opportunities Industrialization Center in Philadelphia, which provided job training and placement—by 1969, it had branches in seventy cities. Black Power was also part of a much larger process of cultural change. The 1960s composed a decade not only of Black Power but also of Black Pride. African American abolitionist John S. Rock had coined the phrase “Black Is Beautiful” in 1858, but in the 1960s, it became an important part of efforts within the African American community to raise self-esteem and encourage pride in African ancestry. Black Pride urged African Americans to reclaim their African heritage and, to promote group solidarity, to substitute African and African-inspired cultural practices, such as handshakes, hairstyles, and dress, for White practices. One of the many cultural products of this movement was the popular television music program Soul Train, created by Don Cornelius in 1969, which celebrated Black culture and aesthetics ().
The late 1960s also delivered what many felt was an overdue correction to racist and intrusive laws. Until then, many states still had anti-miscegenation laws on the books, which prohibited interracial marriages. Over the preceding two decades, fourteen other states had either repealed similar laws or had them invalidated by court cases. But Virginia's Racial Integrity Act remained enforced. In 1958, Richard and Mildred Loving had married in Washington D.C before returning to Virginia. The next month, police entered their house after midnight to arrest and jail the couple. After an initial trial and conviction, a judge suspended their sentence on condition that they leave the state. Unable to travel as a couple to visit their families, the Lovings sought the help of the American Civil Liberties Union. After a series of appellate decisions, the case reached the Supreme Court, which in 1967 unanimously ruled that the race-based marriage prohibitions violated several aspects of the 14th Amendment. The Lovings were free to be a public couple, and the remaining anti-miscegenation state laws were invalidated. Decades later, the case would be referenced in several court decisions regarding same-sex marriage.
### THE MEXICAN AMERICAN FIGHT FOR CIVIL RIGHTS
The African American bid for full citizenship was surely the most visible of the battles for civil rights taking place in the United States. However, other minority groups that had been legally discriminated against or otherwise denied access to economic and educational opportunities began to increase efforts to secure their rights in the 1960s. Like the African American movement, the Mexican American civil rights movement won its earliest victories in the federal courts. In 1947, in Mendez v. Westminster, the U.S. Court of Appeals for the Ninth Circuit ruled that segregating children of Hispanic descent was unconstitutional. In 1954, the same year as Brown v. Board of Education, Mexican Americans prevailed in Hernandez v. Texas, when the U.S. Supreme Court extended the protections of the Fourteenth Amendment to all ethnic groups in the United States.
The highest-profile struggle of the Mexican American civil rights movement was the fight that Cesar Chavez () and Dolores Huerta waged in the fields of California to organize migrant farm workers. In 1962, Chavez and Huerta founded the National Farm Workers Association (NFWA). In 1965, when Filipino grape pickers led by Filipino American Larry Itliong went on strike to call attention to their plight, Chavez lent his support. Workers organized by the NFWA also went on strike, and the two organizations merged to form the United Farm Workers. When Chavez asked American consumers to boycott grapes, politically conscious people around the country heeded his call, and many unionized longshoremen refused to unload grape shipments. In 1966, Chavez led striking workers to the state capitol in Sacramento, further publicizing the cause. Martin Luther King, Jr. telegraphed words of encouragement to Chavez, whom he called a “brother.” The strike ended in 1970 when California farmers recognized the right of farm workers to unionize. However, the farm workers did not gain all they sought, and the larger struggle did not end.
The equivalent of the Black Power movement among Mexican Americans was the Chicano Movement. Proudly adopting a derogatory term for Mexican Americans, Chicano activists demanded increased political power for Mexican Americans, education that recognized their cultural heritage, and the restoration of lands taken from them at the end of the Mexican-American War in 1848. One of the founding members, Rodolfo “Corky” Gonzales, launched the Crusade for Justice in Denver in 1965, to provide jobs, legal services, and healthcare for Mexican Americans. From this movement arose La Raza Unida, a political party that attracted many Mexican American college students. Elsewhere, Reies López Tijerina fought for years to reclaim lost and illegally expropriated ancestral lands in New Mexico; he was one of the co-sponsors of the Poor People’s March on Washington in 1967.
### Section Summary
The African American civil rights movement made significant progress in the 1960s. While Congress played a role by passing the Civil Rights Act of 1964, the Voting Rights Act of 1965, and the Civil Rights Act of 1968, the actions of civil rights groups such as CORE, the SCLC, and SNCC were instrumental in forging new paths, pioneering new techniques and strategies, and achieving breakthrough successes. Civil rights activists engaged in sit-ins, freedom rides, and protest marches, and registered African American voters. Despite the movement’s many achievements, however, many grew frustrated with the slow pace of change, the failure of the Great Society to alleviate poverty, and the persistence of violence against African Americans, particularly the tragic 1968 assassination of Martin Luther King, Jr. Many African Americans in the mid- to late 1960s adopted the ideology of Black Power, which promoted their work within their own communities to redress problems without the aid of White people. The Mexican American civil rights movement, led largely by Cesar Chavez, also made significant progress at this time. The emergence of the Chicano Movement signaled Mexican Americans’ determination to seize their political power, celebrate their cultural heritage, and demand their citizenship rights.
### Review Questions
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# Contesting Futures: America in the 1960s
## Challenging the Status Quo
By the 1960s, a generation of White Americans raised in prosperity and steeped in the culture of conformity of the 1950s had come of age. However, many of these baby boomers (those born between 1946 and 1964) rejected the conformity and luxuries that their parents had provided. These young, middle-class Americans, especially those fortunate enough to attend college when many of their working-class and African American contemporaries were being sent to Vietnam, began to organize to fight for their own rights and end the war that was claiming the lives of so many.
### THE NEW LEFT
By 1960, about one-third of the U.S. population was living in the suburbs; during the 1960s, the average family income rose by 33 percent. Material culture blossomed, and at the end of the decade, 70 percent of American families owned washing machines, 83 percent had refrigerators or freezers, and almost 80 percent had at least one car. Entertainment occupied a larger part of both working- and middle-class leisure hours. By 1960, American consumers were spending $85 billion a year on entertainment, double the spending of the preceding decade; by 1969, about 79 percent of American households had black-and-white televisions, and 31 percent could afford color sets. Movies and sports were regular aspects of the weekly routine, and the family vacation became an annual custom for both the middle and working class.
Meanwhile, baby boomers, many raised in this environment of affluence, streamed into universities across the nation in unprecedented numbers looking to “find” themselves. Instead, they found traditional systems that forced them to take required courses, confined them to rigid programs of study, and surrounded them with rules limiting what they could do in their free time. These young people were only too willing to take up Kennedy’s call to action, and many did so by joining the civil rights movement. To them, it seemed only right for the children of the “greatest generation” to help those less privileged to fight battles for justice and equality. The more radical aligned themselves with the New Left, activists of the 1960s who rejected the staid liberalism of the Democratic Party. New Left organizations sought reform in areas such as civil rights and women’s rights, campaigned for free speech and more liberal policies toward drug use, and condemned the war in Vietnam.
One of the most prominent New Left groups was Students for a Democratic Society (SDS). Organized in 1960, SDS held its first meeting at the University of Michigan, Ann Arbor. Its philosophy was expressed in its manifesto, the Port Huron Statement, written by Tom Hayden and adopted in 1962, affirming the group’s dedication to fighting economic inequality and discrimination. It called for greater participation in the democratic process by ordinary people, advocated civil disobedience, and rejected the anti-Communist position held by most other groups committed to social reform in the United States.
SDS members demanded that universities allow more student participation in university governance and shed their entanglements with the military-industrial complex. They sought to rouse the poor to political action to defeat poverty and racism. In the summer of 1964, a small group of SDS members moved into the uptown district of Chicago and tried to take on racism and poverty through community organization. Under the umbrella of their Economic Research and Action Project, they created JOIN (Jobs or Income Now) to address problems of urban poverty and resisted plans to displace the poor under the guise of urban renewal. They also called for police review boards to end police brutality, organized free breakfast programs, and started social and recreational clubs for neighborhood youth. Eventually, the movement fissured over whether to remain a campus-based student organization or a community-based development organization.
During the same time that SDS became active in Chicago, another student movement emerged on the West Coast, when actions by student activists at the University of California, Berkeley, led to the formation of Berkeley’s Free Speech Movement in 1964. University rules prohibited the solicitation of funds for political causes by anyone other than members of the student Democratic and Republican organizations, and restricted advocacy of political causes on campus. In October 1964, when a student handing out literature for CORE refused to show campus police officers his student ID card, he was promptly arrested. Instantly, the campus police car was surrounded by angry students, who refused to let the vehicle move for thirty-two hours until the student was released. In December, students organized a massive sit-in to resolve the issue of political activities on campus. While unsuccessful in the short term, the movement inspired student activism on campuses throughout the country.
A target of many student groups was the war in Vietnam (). In April 1965, SDS organized a march on Washington for peace; about twenty thousand people attended. That same week, the faculty at the University of Michigan suspended classes and conducted a 24-hour “teach-in” on the war. The idea quickly spread, and on May 15, the first national “teach-in” was held at 122 colleges and universities across the nation. Originally designed to be a debate on the pros and cons of the war, at Berkeley, the teach-ins became massive antiwar rallies. By the end of that year, there had been antiwar rallies in some sixty cities.
### WOMEN’S RIGHTS
On the national scene, the civil rights movement was creating a climate of protest and claiming rights and new roles in society for people of color. Women played significant roles in organizations fighting for civil rights like SNCC and SDS. However, they often found that those organizations, enlightened as they might be about racial issues or the war in Vietnam, could still be influenced by patriarchal ideas of male superiority. Two members of SNCC, Casey Hayden and Mary King, presented some of their concerns about their organization’s treatment of women in a document entitled “On the Position of Women in SNCC.” Stokely Carmichael responded that the appropriate position for women in SNCC was “prone.”
Just as the abolitionist movement made nineteenth-century women more aware of their lack of power and encouraged them to form the first women’s rights movement, the protest movements of the 1960s inspired many White and middle-class women to create their own organized movement for greater rights. Not all were young women engaged in social protest. Many were older, married women who found the traditional roles of housewife and mother unfulfilling. In 1963, writer and feminist Betty Friedan published The Feminine Mystique in which she contested the post-World War II belief that it was women’s destiny to marry and bear children. Friedan’s book was a best-seller and began to raise the consciousness of many women who agreed that homemaking in the suburbs sapped them of their individualism and left them unsatisfied.
The Civil Rights Act of 1964, which prohibited discrimination in employment on the basis of race, color, national origin, and religion, also prohibited, in Title VII, discrimination on the basis of sex. Ironically, protection for women had been included at the suggestion of a Virginia congressman in an attempt to prevent the act’s passage; his reasoning seemed to be that, while a White man might accept that African Americans needed and deserved protection from discrimination, the idea that women deserved equality with men would be far too radical for any of his male colleagues to contemplate. Nevertheless, the act passed, although the struggle to achieve equal pay for equal work continues today.
Medical science also contributed a tool to assist women in their liberation. In 1960, the U.S. Food and Drug Administration approved the birth control pill, freeing women from the restrictions of pregnancy and childbearing. Women who were able to limit, delay, and prevent reproduction were freer to work, attend college, and delay marriage. Within five years of the pill’s approval, some six million women were using it.
The pill was the first medicine ever intended to be taken by people who were not sick. Even conservatives saw it as a possible means of making marriages stronger by removing the fear of an unwanted pregnancy and improving the health of women. Its opponents, however, argued that it would promote sexual promiscuity, undermine the institutions of marriage and the family, and destroy the moral code of the nation. By the early 1960s, thirty states had made it a criminal offense to sell contraceptive devices.
In 1966, the National Organization for Women (NOW) formed and proceeded to set an agenda for the feminist movement (). Framed by a statement of purpose written by Friedan, the agenda began by proclaiming NOW’s goal to make possible women’s participation in all aspects of American life and to gain for them all the rights enjoyed by men. Among the specific goals was the passage of the Equal Rights Amendment (yet to be adopted).
More radical feminists, like their colleagues in other movements, were dissatisfied with merely redressing economic issues and devised their own brand of consciousness-raising events and symbolic attacks on women’s oppression. The most famous of these was an event staged in September 1968 by New York Radical Women. Protesting stereotypical notions of femininity and rejecting traditional gender expectations, the group demonstrated at the Miss America Pageant in Atlantic City, New Jersey, to bring attention to the contest’s—and society’s—exploitation of women. Their protest documents also noted that the contest was closed to Black and Native American women due to a rule indicating contestants must be "of the White race." (A Cherokee woman had won before the rule was instituted.) The protestors crowned a sheep Miss America and then tossed instruments of women’s oppression, including high-heeled shoes, curlers, girdles, and bras, into a “freedom trash can.” News accounts famously, and incorrectly, described the protest as a “bra burning," which at the time was a way to demean and trivialize the issue of women's rights.
Other protests gave women a more significant voice in a male-dominated social, political, and entertainment climate. For decades, Ladies Home Journal had been a highly influential women's magazine, managed and edited almost entirely by men. Men even wrote the advice columns and beauty articles. In 1970, protesters held a sit-in at the magazine's offices, demanding that the company hire a woman editor-in-chief, add women and non-White writers at fair pay, and expand the publication's focus. The protest was generally successful, and also inspired the birth of a different type of women's magazine.
Gloria Steinem had pushed through gender barriers to take on serious journalism subjects, and had emerged as a prominent advocate for women's rights. Through her work, Steinem met Dorothy Pittman-Hughes, who had founded New York City's first shelter for domestic violence victims as well as the city's Agency for Child Development. Together they founded Ms. Magazine, which avoided articles on homemaking and fashion in favor of pieces on women's rights and empowerment. Ms. showcased powerful and accomplished women such as Shirley Chisholm and Sissy Farenthold, and was among the first publications to bring domestic violence, sexual harassment, and body image issues to the national conversation.
### Section Summary
During the 1960s, many people rejected traditional roles and expectations. Influenced and inspired by the civil rights movement, college students of the baby boomer generation and women of all ages began to fight to secure a stronger role in American society. As members of groups like SDS and NOW asserted their rights and strove for equality for themselves and others, they upended many accepted norms and set groundbreaking social and legal changes in motion. Many of their successes continue to be felt today, while other goals remain unfulfilled.
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# Political Storms at Home and Abroad, 1968-1980
## Introduction
From May 4 to November 4, 1974, a universal exposition was held in the city of Spokane, Washington. This world’s fair, Expo ‘74, and the postage stamp issued to commemorate it, reflected many of the issues and interests of the 1970s (). The stamp features psychedelic colors, and the character of the Cosmic Runner in the center wears bellbottoms, a popular fashion at the time. The theme of the fair was the environment, a subject beginning to be of great concern to people in the United States, especially the younger generation and those in the hippie counterculture. In the 1970s, the environment, social justice, distrust of the government, and a desire to end the war in Vietnam—the concerns and attitudes of younger people, women, gays and lesbians, and people of color—began to draw the attention of the mainstream as well. |
# Political Storms at Home and Abroad, 1968-1980
## Identity Politics in a Fractured Society
The political divisions that plagued the United States in the 1960s were reflected in the rise of identity politics in the 1970s. As people lost hope of reuniting as a society with common interests and goals, many focused on issues of significance to the subgroups to which they belonged, based on culture, ethnicity, sexual orientation, gender, and religion.
### HIPPIES AND THE COUNTERCULTURE
In the late 1960s and early 1970s, many young people came to embrace a new wave of cultural dissent. The counterculture offered an alternative to the bland homogeneity of American middle-class life, patriarchal family structures, self-discipline, unquestioning patriotism, and the acquisition of property. In fact, there were many alternative cultures.
“Hippies” rejected the conventions of traditional society. Men sported beards and grew their hair long; both men and women wore clothing from non-Western cultures, defied their parents, rejected social etiquettes and manners, and turned to music as an expression of their sense of self. Casual sex between unmarried men and women was acceptable. Drug use, especially of marijuana and psychedelic drugs like LSD and peyote, was common. Most hippies were also deeply attracted to the ideas of peace and freedom. They protested the war in Vietnam and preached a doctrine of personal freedom to be and act as one wished.
Some hippies dropped out of mainstream society altogether and expressed their disillusionment with the cultural and spiritual limitations of American freedom. They joined communes, usually in rural areas, to share a desire to live closer to nature, respect for the earth, a dislike of modern life, and a disdain for wealth and material goods. Many communes grew their own organic food. Others abolished the concept of private property, and all members shared willingly with one another. Some sought to abolish traditional ideas regarding love and marriage, and free love was practiced openly. One of the most famous communes was The Farm, established in Tennessee in 1971. Residents adopted a blend of Christian and Asian beliefs. They shared housing, owned no private property except tools and clothing, advocated nonviolence, and tried to live as one with nature, becoming vegetarians and avoiding the use of animal products. They smoked marijuana in an effort to reach a higher state of consciousness and to achieve a feeling of oneness and harmony.
Music, especially rock and folk music, occupied an important place in the counterculture. Concerts provided the opportunity to form seemingly impromptu communities to celebrate youth, rebellion, and individuality. In mid-August 1969, nearly 400,000 people attended a music festival in rural Bethel, New York, many for free (). They jammed roads throughout the state, and thousands had to be turned around and sent home. Thirty-two acts performed for a crowd that partook freely of marijuana, LSD, and alcohol during the rainy three-day event that became known as Woodstock (after the nearby town) and became the cultural touchstone of a generation. No other event better symbolized the cultural independence and freedom of Americans coming of age in the 1960s.
### AMERICAN INDIAN PROTEST
As the young, primarily White men and women who became hippies strove to create new identities for themselves, they borrowed liberally from other cultures, including that of Native Americans. At the same time, many Native Americans were themselves seeking to maintain their culture or retrieve elements that had been lost. In 1968, a group of American Indian activists, including Dennis Banks, George Mitchell, and Clyde Bellecourt, convened a gathering of two hundred people in Minneapolis, Minnesota, and formed the American Indian Movement (AIM) (). The organizers were urban dwellers frustrated by decades of poverty and discrimination. In 1970, the average life expectancy of Native Americans was forty-six years compared to the national average of sixty-nine. The suicide rate was twice that of the general population, and the infant mortality rate was the highest in the country. Half of all Native Americans lived on reservations, where unemployment reached 50 percent. Among those in cities, 20 percent lived below the poverty line.
On November 20, 1969, a small group of Native American activists landed on Alcatraz Island (the former site of a notorious federal prison) in San Francisco Bay. They announced plans to build an American Indian cultural center, including a history museum, an ecology center, and a spiritual sanctuary. People on the mainland provided supplies by boat, and celebrities visited Alcatraz to publicize the cause. More people joined the occupiers until, at one point, they numbered about four hundred. From the beginning, the federal government negotiated with them to persuade them to leave. They were reluctant to accede, but over time, the occupiers began to drift away of their own accord. Government forces removed the final holdouts on June 11, 1971, nineteen months after the occupation began.
The next major demonstration came in 1972 when AIM members and others marched on Washington, DC—a journey they called the “Trail of Broken Treaties”—and occupied the offices of the Bureau of Indian Affairs (BIA). The group presented a list of demands, which included improved housing, education, and economic opportunities in Native American communities; the drafting of new treaties; the return of Native lands; and protections for Native religions and culture.
The most dramatic event staged by AIM was the occupation of the community of Wounded Knee, South Dakota, in February 1973. Wounded Knee, on the Pine Ridge Indian Reservation, had historical significance: It was the site of an 1890 massacre of members of the Lakota tribe by the U.S. Army. AIM went to the reservation following the failure of a group of Oglala to impeach the tribal president Dick Wilson, whom they accused of corruption and the use of strong-arm tactics to silence critics. AIM used the occasion to criticize the U.S. government for failing to live up to its treaties with native peoples.
The federal government surrounded the area with U.S. marshals, FBI agents, and other law enforcement forces. A siege ensued that lasted seventy-one days, with frequent gunfire from both sides, wounding a U.S. marshal as well as an FBI agent, and killing two Native Americans. The government did very little to meet the protesters’ demands. Two AIM leaders, Dennis Banks and Russell Means, were arrested, but charges were later dismissed. The Nixon administration had already halted the federal policy of termination and restored millions of acres to tribes. Increased funding for Native American education, healthcare, legal services, housing, and economic development followed, along with the hiring of more Native American employees in the BIA.
### GAY RIGHTS
Combined with the sexual revolution and the feminist movement of the 1960s, the counterculture helped establish a climate that fostered the struggle for gay and lesbian rights. Lesbian, gay, bisexual, transgender, and queer people (later abbreviated as LGBTQ) had long been denied rights and had been perceived as threatening. As discussed earlier, LGBTQ veterans were dishonorably discharged without benefits, and LGBTQ people were cast under a cloud of suspicion during the McCarthy era. But that mistreatment was only a small part of the anti-gay oppression. By most considerations, LGBTQ people's very existence was criminalized. Sexual relations between same-sex couples were illegal in most states until the 1980s, and various city and state ordinances disallowed members of the same sex from dancing or even holding hands with each other. Other laws were used to require that people wear clothing deemed appropriate to their gender. These statutes gave authorities the ability to harass, detain, arrest, sexually humiliate, and prosecute people for their identity. Perhaps worse, it led to extensive anti-LGBTQ violence that was rarely investigated or prosecuted.
Many gay rights groups were founded in Los Angeles and San Francisco, cities that were administrative centers in the network of U.S. military installations and the places where many gay men suffered dishonorable discharges. The first postwar organization for gay and lesbian civil rights, the Mattachine Society, was launched in Los Angeles in 1950. The first national organization for lesbians, the Daughters of Bilitis, was founded in San Francisco five years later. In 1966, the city became home to the world’s first organization for transgender people, the National Transsexual Counseling Unit (transsexual was a more commonly used term at the time); and in 1967, the Sexual Freedom League of San Francisco was born.
Through these organizations and others, LGBTQ activists fought against the criminalization and discrimination of their sexual identities on a number of occasions throughout the 1960s, employing strategies of both protests and litigation. However, the most famous event in the gay rights movement took place not in San Francisco but in New York City. Early in the morning of June 28, 1969, police raided a Greenwich Village gay bar called the Stonewall Inn. Although such raids were common, the response of the Stonewall patrons was anything but. As the police prepared to arrest many of the customers, especially transgender people, who were particular targets for police harassment, a crowd began to gather. Angered by the brutal treatment of the prisoners, the crowd attacked. Beer bottles and bricks were thrown. The police barricaded themselves inside the bar and waited for reinforcements. The riot continued for several hours and resumed the following night. Shortly thereafter, activists formed the Gay Liberation Front and Gay Activists’ Alliance and began to protest discrimination, homophobia, and violence against gay people, promoting gay liberation and gay pride.
With a call for gay men and women to “come out”—a consciousness-raising campaign that shared many principles with the counterculture, gay and lesbian communities moved from the urban underground into the political sphere. Gay rights activists protested strongly against the official position of the American Psychiatric Association (APA), which categorized homosexuality as a mental illness and often resulted in job loss, loss of custody, and other serious personal consequences. By 1974, the APA had ceased to classify homosexuality as a form of mental illness but continued to consider it a “sexual orientation disturbance.” Nevertheless, in 1974, Kathy Kozachenko became the first openly lesbian woman voted into office in Ann Arbor, Michigan. In 1977, Harvey Milk became California’s first openly gay man elected to public office, although his service on San Francisco’s board of supervisors, along with that of San Francisco mayor George Moscone, was cut short by the bullet of disgruntled former city supervisor Dan White.
One of the first steps toward greater LGTBQ rights was the decriminalization of relations. While police harassment would continue and hate crimes would escalate, the elimination of criminality simply for being gay was an important and consequential initial victory. Illinois was the first state to decriminalize same-sex relations in 1962, but was joined by only one other state (Connecticut) in the 1960s. The next decade saw 18 more states eliminate the bans, and the rest of the nation gradually reduced penalties or ceased enforcement of their codes. But in many cases, since nearly half of the states had such laws on the books, they could be used to justify a range of discriminatory acts and practices. (Consensual same-sex relations would be made legal nationwide in 2003 due to a Supreme Court decision.)
### MAYBE NOT NOW
The feminist push for greater rights continued through the 1970s (). The media often ridiculed feminists as “women’s libbers” and focused on more radical organizations like W.I.T.C.H. (Women’s International Terrorist Conspiracy from Hell), a loose association of activist groups. Many reporters stressed the most unusual goals of the most radical women—calls for the abolition of marriage and demands that manholes be renamed “personholes.”
The majority of feminists, however, sought meaningful accomplishments. In the 1970s, they opened battered women’s shelters and successfully fought for protection from employment discrimination for pregnant women, reform of rape laws (such as the abolition of laws requiring a witness to corroborate a woman’s report of rape), criminalization of domestic violence, and funding for schools that sought to counter sexist stereotypes of women. In 1973, the U.S. Supreme Court in Roe v. Wade invalidated a number of state laws under which abortions obtained during the first three months of pregnancy were illegal. This made a nontherapeutic abortion a legal medical procedure nationwide.
Many advances in women’s rights were the result of women’s greater engagement in politics. For example, Patsy Mink, the first Asian American woman elected to Congress, was the co-author of the Education Amendments Act of 1972, Title IX of which prohibits sex discrimination in education. Mink had been interested in fighting discrimination in education since her youth, when she opposed racial segregation in campus housing while a student at the University of Nebraska. She went to law school after being denied admission to medical school because of her gender. Like Mink, many other women sought and won political office, many with the help of the National Women’s Political Caucus (NWPC). In 1971, the NWPC was formed by Bella Abzug, Gloria Steinem, Shirley Chisholm, Myrlie Evers-Williams, and other leading feminists to encourage women’s participation in political parties, elect women to office, and raise money for their campaigns ().
Shirley Chisholm personally took up the mantle of women's involvement in politics. Born of immigrant parents, she earned degrees from Brooklyn College and Columbia University, and began a career in early childhood education and advocacy. In the 1950's she joined various political action groups, worked on election campaigns, and pushed for housing and economic reforms. After leaving one organization over its refusal to involve women in the decision-making process, she sought to increase gender and racial diversity within political and activist organizations throughout New York City. In 1968, she became the first Black woman elected to Congress. Refusing to take the quiet role expected of new Representatives, she immediately began sponsoring bills and initiatives. She spoke out against the Vietnam War, and fought for programs such as Head Start and the national school lunch program, which was eventually signed into law after Chisholm led an effort to override a presidential veto. Chisholm would eventually undertake a groundbreaking presidential run in 1972.
As a Presidential candidate, Chisholm faced pressure from an unexpected source: her closest colleagues. Men within the Congressional Black Caucus, which she co-founded, disagreed with her pluralistic political coalition. The Democratic party did not allow her to participate in the televised primary debates, and she was only allowed one speech. She noted, “Black male politicians are no different from white male politicians. This ‘woman thing’ is so deep. I’ve found it out in this campaign if I never knew it before.” Despite all this, Shirley Chisholm earned ten percent of the total Democratic delegates, and became a nationally influential figure.
The ultimate political goal of the National Organization for Women (NOW) was the passage of an Equal Rights Amendment (ERA). The amendment passed Congress in March 1972, and was sent to the states for ratification with a deadline of seven years for passage; if the amendment was not ratified by thirty-eight states by 1979, it would die. Twenty-two states ratified the ERA in 1972, and eight more in 1973. In the next two years, only four states voted for the amendment. In 1979, still four votes short, the amendment received a brief reprieve when Congress agreed to a three-year extension, but it never passed, as the result of the well-organized opposition of Christian and other socially conservative, grassroots organizations.
### Section Summary
In the late 1960s and 1970s, Native Americans, LGBTQ people, and women organized to change discriminatory laws and pursue government support for their interests, a strategy known as identity politics. Others, disenchanted with the status quo, distanced themselves from White, middle-class America by forming their own countercultures centered on a desire for peace, the rejection of material goods and traditional morality, concern for the environment, and drug use in pursuit of spiritual revelations. These groups, whose aims and tactics posed a challenge to the existing state of affairs, often met with hostility from individuals, local officials, and the U.S. government alike. Still, they persisted, determined to further their goals and secure for themselves the rights and privileges to which they were entitled as American citizens.
### Review Questions
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# Political Storms at Home and Abroad, 1968-1980
## Coming Apart, Coming Together
The presidential election of 1968 revealed a rupture of the New Deal coalition that had come together under Franklin Roosevelt in the 1930s. The Democrats were divided by internal dissension over the Vietnam War, the civil rights movement, and the challenges of the New Left. Meanwhile, the Republican candidate, Richard Nixon, won voters in the South, Southwest, and northern suburbs by appealing to their anxieties about civil rights, women’s rights, antiwar protests, and the counterculture taking place around them. Nixon spent his first term in office pushing measures that slowed the progress of civil rights and sought to restore economic stability. His greatest triumphs were in foreign policy. But his largest priority throughout his first term was his reelection in 1972.
### THE “NEW NIXON”
The Republicans held their 1968 national convention from August 5–8 in Miami, Florida. Richard Nixon quickly emerged as the frontrunner for the nomination, ahead of Nelson Rockefeller and Ronald Reagan. This success was not accidental: From 1962, when he lost his bid for the governorship of California, to 1968, Nixon had been collecting political credits by branding himself as a candidate who could appeal to mainstream voters and by tirelessly working for other Republican candidates. In 1964, for example, he vigorously supported Barry Goldwater’s presidential bid and thus built good relationships with the new conservative movement in the Republican Party.
Although Goldwater lost the 1964 election, his vigorous rejection of New Deal state and social legislation, along with his support of states’ rights, proved popular in the Deep South, which had resisted federal efforts at racial integration. Taking a lesson from Goldwater’s experience, Nixon also employed a southern strategy in 1968. Denouncing segregation and the denial of the vote to African Americans, he nevertheless maintained that southern states be allowed to pursue racial equality at their own pace and criticized forced integration. Nixon thus garnered the support of South Carolina’s senior senator and avid segregationist Strom Thurmond, which helped him win the Republican nomination on the first ballot.
Nixon also courted northern, blue-collar workers, whom he later called the silent majority, to acknowledge their belief that their voices were seldom heard. These voters feared the social changes taking place in the country: Antiwar protests challenged their own sense of patriotism and civic duty, whereas the recreational use of new drugs threatened their cherished principles of self-discipline, and urban riots invoked the specter of a racial reckoning. Government action on behalf of the marginalized raised the question of whether its traditional constituency—the White middle class—would lose its privileged place in American politics. Some felt left behind as the government turned to the problems of African Americans. Nixon’s promises of stability and his emphasis on law and order appealed to them. He portrayed himself as a fervent patriot who would take a strong stand against racial unrest and antiwar protests. Nixon harshly critiqued Lyndon Johnson’s Great Society, and he promised a secret plan to end the war in Vietnam honorably and bring home the troops. He also promised to reform the Supreme Court, which he contended had gone too far in “coddling criminals.” Under Chief Justice Earl Warren, the court had used the due process and equal protection clauses of the Fourteenth Amendment to grant those accused under state law the ability to defend themselves and secure protections against unlawful search and seizure, cruel and unusual punishment, and self-incrimination.
Nixon had found the political capital that would ensure his victory in the suburbs, which produced more votes than either urban or rural areas. He championed “middle America,” which was fed up with social convulsions, and called upon the country to come together. His running mate, Spiro T. Agnew, a former governor of Maryland, blasted the Democratic ticket as fiscally irresponsible and “soft on communism.” Nixon and Agnew’s message thus appealed to northern middle-class and blue-collar White people as well as southern White people who had fled to the suburbs in the wake of the Supreme Court’s pro-integration decision in Brown v. Board of Education ().
### DEMOCRATS IN DISARRAY
By contrast, in early 1968, the political constituency that Lyndon Johnson had cobbled together to win the presidency in 1964 seemed to be falling apart. When Eugene McCarthy, the Democratic senator from Minnesota, announced that he would challenge Johnson in the primaries in an explicitly antiwar campaign, Johnson was overwhelmingly favored by Democratic voters. But then the Tet Offensive in Vietnam exploded on American television screens on January 31, playing out on the nightly news for weeks. On February 27, Walter Cronkite, a highly respected television journalist, offered his opinion that the war in Vietnam was unwinnable. When the votes were counted in New Hampshire on March 12, McCarthy had won twenty of the state’s twenty-four delegates.
McCarthy’s popularity encouraged Robert (Bobby) Kennedy to also enter the race. Realizing that his war policies could unleash a divisive fight within his own party for the nomination, Johnson announced his withdrawal on March 31, fracturing the Democratic Party. One faction consisted of the traditional party leaders who appealed to unionized, blue-collar constituents and White ethnics (Americans with recent European immigrant backgrounds). This group fell in behind Johnson’s vice president, Hubert H. Humphrey, who took up the mainstream party’s torch almost immediately after Johnson’s announcement. The second group consisted of idealistic young activists who had slogged through the snows of New Hampshire to give McCarthy a boost and saw themselves as the future of the Democratic Party. The third group, composed of Catholics, African Americans and other minorities, and some of the young, antiwar element, galvanized around Robert Kennedy (). Finally, there were the southern Democrats, the Dixiecrats, who opposed the advances made by the civil rights movement. Some found themselves attracted to the Republican candidate Richard Nixon. Many others, however, supported the third-party candidacy of segregationist George C. Wallace, the former governor of Alabama. Wallace won close to ten million votes, which was 13.5 percent of all votes cast. He was particularly popular in the South, where he carried five states and received forty-six Electoral College votes.
Kennedy and McCarthy fiercely contested the remaining primaries of the 1968 season. There were only fifteen at that time. McCarthy beat Kennedy handily in Wisconsin, Pennsylvania, and Massachusetts. Kennedy took Indiana and Nebraska before losing Oregon to McCarthy. Kennedy’s only hope was that a strong enough showing in the California primary on June 4 might swing uncommitted delegates his way. He did manage to beat McCarthy, winning 46 percent of the vote to McCarthy’s 42 percent, but it was a fruitless victory. As he attempted to exit the Ambassador Hotel in Los Angeles after his victory speech, Kennedy was shot; he died twenty-six hours later. His killer, Sirhan B. Sirhan, a Jordanian immigrant, had allegedly targeted him for advocating military support for Israel in its conflict with neighboring Arab states.
Going into the nominating convention in Chicago in 1968, Humphrey, who promised to pursue the “Politics of Joy,” seemed clearly in command of the regular party apparatus. But the national debates over civil rights, student protests, and the Vietnam War had made 1968 a particularly anguished year, and many people felt anything but joyful. Some party factions hoped to make their voices heard; others wished to disrupt the convention altogether. Among them were antiwar protestors, hippies, and Yippies—members of the leftist, anarchistic Youth International Party organized by Jerry Rubin and Abbie Hoffman—who called for the establishment of a new nation consisting of cooperative institutions to replace those currently in existence. To demonstrate their contempt for “the establishment” and the proceedings inside the hall, the Yippies nominated a pig named Pigasus for president.
A chaotic scene developed inside the convention hall and outside at Grant Park, where the protesters camped. Chicago’s mayor, Richard J. Daley, was anxious to demonstrate that he could maintain law and order, especially because several days of destructive rioting had followed the murder of Martin Luther King, Jr. earlier that year. He thus let loose a force of twelve thousand police officers, six thousand members of the Illinois National Guard, and six thousand U.S. Army soldiers. Television cameras caught what later became known as a “police riot”: Armed officers made their way into crowds of law-abiding protesters, clubbing anyone they encountered and setting off tear gas canisters. The protesters fought back. Inside the convention hall, a Democratic senator from Connecticut called for adjournment, whereas other delegates insisted on proceeding. Ironically, Hubert Humphrey received the nomination and gave an acceptance speech in which he spoke in support of “law and order.” When the convention ended, Rubin, Hoffman, and five other protesters (called the “Chicago Seven”) were placed on trial for inciting a riot ().
### THE DOMESTIC NIXON
The images of violence and the impression of things spinning out of control seriously damaged Humphrey’s chances for victory. Many liberals and young antiwar activists, disappointed by his selection over McCarthy and still shocked by the death of Robert Kennedy, did not vote for Humphrey. Others turned against him because of his failure to chastise the Chicago police for their violence. Some resented the fact that Humphrey had received 1,759 delegates on the first ballot at the convention, nearly three times the number won by McCarthy, even though in the primaries, he had received only 2 percent of the popular vote. Many loyal Democratic voters at home, shocked by the violence they saw on television, turned away from their party, which seemed to have attracted dangerous “radicals,” and began to consider Nixon’s promises of law and order.
As the Democratic Party collapsed, Nixon successfully campaigned for the votes of both working- and middle-class White Americans, winning the 1968 election. Although Humphrey received nearly the same percentage of the popular vote, Nixon easily won the Electoral College, gaining 301 votes to Humphrey’s 191 and Wallace’s 46.
Once elected, Nixon began to pursue a policy of deliberate neglect of the civil rights movement and the needs of ethnic minorities. For example, in 1969, for the first time in fifteen years, federal lawyers sided with the state of Mississippi when it sought to slow the pace of school desegregation. Similarly, Nixon consistently showed his opposition to busing to achieve racial desegregation. He saw that restricting African American activity was a way of undercutting a source of votes for the Democratic Party and sought to overhaul the provisions of the Voting Rights Act of 1965. In March 1970, he commented that he did not believe an “open” America had to be homogeneous or fully integrated, maintaining that it was “natural” for members of ethnic groups to live together in their own enclaves. In other policy areas, especially economic ones, Nixon was either moderate or supportive of the progress of African Americans; for example, he expanded affirmative action, a program begun during the Johnson administration to improve employment and educational opportunities for racial minorities.
Although Nixon always kept his eye on the political environment, the economy required attention. The nation had enjoyed seven years of expansion since 1961, but inflation (a general rise in prices) was threatening to constrict the purchasing power of the American consumer and therefore curtail economic expansion. Nixon tried to appeal to fiscal conservatives in the Republican Party, reach out to disaffected Democrats, and, at the same time, work with a Democratic Party-controlled Congress. As a result, Nixon’s approach to the economy seemed erratic. Despite the heavy criticisms he had leveled against the Great Society, he embraced and expanded many of its features. In 1969, he signed a tax bill that eliminated the investment tax credit and moved some two million of the poorest people off the tax rolls altogether. He federalized the food stamp program and established national eligibility requirements, and signed into law the automatic adjustments for inflation of Social Security payments. On the other hand, he won the praise of conservatives with his “New Federalism”—drastically expanding the use of federal “block grants” to states to spend as they wished without strings attached.
By mid-1970, a recession was beginning and unemployment was 6.2 percent, twice the level under Johnson. After earlier efforts at controlling inflation with controlled federal spending—economists assumed that reduced federal spending and borrowing would curb the amount of money in circulation and stabilize prices—Nixon proposed a budget with an $11 billion deficit in 1971. The hope was that more federal funds in the economy would stimulate investment and job creation. When the unemployment rate refused to budge the following year, he proposed a budget with a $25 billion deficit. At the same time, he tried to fight continuing inflation by freezing wages and prices for ninety days, which proved to be only a temporary fix. The combination of unemployment and rising prices posed an unfamiliar challenge to economists whose fiscal policies of either expanding or contracting federal spending could only address one side of the problem at the cost of the other. This phenomenon of “stagflation”—a term that combined the economic conditions of stagnation and inflation—outlived the Nixon administration, enduring into the early 1980s.
The origins of the nation’s new economic troubles were not just a matter of policy. Postwar industrial development in Asia and Western Europe—especially in Germany and Japan—had created serious competition to American businesses. By 1971, American appetites for imports left foreign central banks with billions of U.S. currency, which had been fixed to gold in the international monetary and trade agreement of Bretton Woods back in 1944. When foreign dollar holdings exceeded U.S. gold reserves in 1971, President Nixon allowed the dollar to flow freely against the price of gold. This caused an immediate 8 percent devaluation of the dollar, made American goods cheaper abroad, and stimulated exports. Nixon’s move also marked the beginning of the end of the dollar’s dominance in international trade.
The situation was made worse in October 1973, when Syria and Egypt jointly attacked Israel to recover territory that had been lost in 1967, starting the Yom Kippur War. The Soviet Union significantly aided its allies, Egypt and Syria, and the United States supported Israel, earning the enmity of Arab nations. In retaliation, the Organization of Arab Petroleum Exporting Countries (OAPEC) imposed an embargo on oil shipments to the United States from October 1973 to March 1974. The ensuing shortage of oil pushed its price from three dollars a barrel to twelve dollars a barrel. The average price of gasoline in the United States shot from thirty-eight cents a gallon before the embargo to fifty-five cents a gallon in June 1974, and the prices of other goods whose manufacture and transportation relied on oil or gas also rose and did not come down. The oil embargo had a lasting impact on the economy and underscored the nation’s interdependency with international political and economic developments.
Faced with high fuel prices, American consumers panicked. Gas stations limited the amount customers could purchase and closed on Sundays as supplies ran low (). To conserve oil, Congress reduced the speed limit on interstate highways to fifty-five miles per hour. People were asked to turn down their thermostats, and automobile manufacturers in Detroit explored the possibility of building more fuel-efficient cars. Even after the embargo ended, prices continued to rise, and by the end of the Nixon years in 1974, inflation had soared to 12.2 percent.
Although Nixon’s economic and civil rights policies differed from those of his predecessors, in other areas, he followed their lead. President Kennedy had committed the nation to putting a man on the moon before the end of the decade. Nixon, like Johnson before him, supported significant budget allocations to the National Aeronautics and Space Administration (NASA) to achieve this goal. On July 20, 1969, hundreds of millions of people around the world watched as astronauts Neil Armstrong and Edwin “Buzz” Aldrin walked on the surface of the moon and planted the U.S. flag. Watching from the White House, President Nixon spoke to the astronauts via satellite phone. The entire project cost the American taxpayer some $25 billion, approximately 4 percent of the nation’s gross national product, and was such a source of pride for the nation that the Soviet Union and China refused to televise it. Coming amid all the struggles and crises that the country was enduring, the moon landing gave citizens a sense of accomplishment that stood in stark contrast to the foreign policy failures, growing economic challenges, and escalating divisions at home.
### NIXON THE DIPLOMAT
Despite the many domestic issues on Nixon’s agenda, he prioritized foreign policy and clearly preferred bold and dramatic actions in that arena. Realizing that five major economic powers—the United States, Western Europe, the Soviet Union, China, and Japan—dominated world affairs, he sought opportunities for the United States to pit the others against each other. In 1969, he announced a new Cold War principle known as the Nixon Doctrine, a policy whereby the United States would continue to assist its allies but would not assume the responsibility of defending the entire non-Communist world. Other nations, like Japan, needed to assume more of the burden of first defending themselves.
Playing what was later referred to as “the China card,” Nixon abruptly reversed two decades of U.S. diplomatic sanctions and hostility to the Communist regime in the People’s Republic of China, when he announced, in August 1971, that he would personally travel to Beijing and meet with China’s leader, Chairman Mao Zedong, in February 1972 (). Nixon hoped that opening up to the Chinese government would prompt its bitter rival, the Soviet Union, to compete for global influence and seek a more productive relationship with the United States. He also hoped that establishing a friendly relationship with China would isolate North Vietnam and ease a peace settlement, allowing the United States to extract its troops from the war honorably. Concurring that the Soviet Union should be restrained from making advances in Asia, Nixon and Chinese premier Zhou Enlai agreed to disagree on several issues and ended up signing a friendship treaty. They promised to work towards establishing trade between the two nations and to eventually establishing full diplomatic relations with each other.
Continuing his strategy of pitting one Communist nation against another, in May 1972, Nixon made another newsworthy trip, traveling to Moscow to meet with the Soviet leader Leonid Brezhnev. The two discussed a policy of détente, a relaxation of tensions between their nations, and signed the Strategic Arms Limitation Treaty (SALT), which limited each side to deploying only two antiballistic missile systems. It also limited the number of nuclear missiles maintained by each country. In 1974, a protocol was signed that reduced antiballistic missile sites to one per country, since neither country had yet begun to build its second system. Moreover, the two sides signed agreements to allow scientific and technological exchanges, and promised to work towards a joint space mission.
### Section Summary
When a new Republican constituency of moderate southerners and northern, blue-collar workers voted Richard Nixon into the White House in 1968, many were hopeful. In the wake of antiwar and civil rights protests, and the chaos of the 1968 Democratic National Convention, many Americans welcomed Nixon’s promise to uphold law and order. During his first term, Nixon strode a moderate, middle path in domestic affairs, attempting with little success to solve the problems of inflation and unemployment through a combination of austerity and deficit spending. He made substantial progress in foreign policy, however, establishing diplomatic relations with China for the first time since the Communist Revolution and entering into a policy of détente with the Soviet Union.
### Review Questions
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# Political Storms at Home and Abroad, 1968-1980
## Vietnam: The Downward Spiral
As early as 1967, critics of the war in Vietnam had begun to call for the repeal of the Gulf of Tonkin Resolution, which gave President Johnson the authority to conduct military operations in Vietnam in defense of an ally, South Vietnam. Nixon initially opposed the repeal efforts, claiming that doing so might have consequences that reached far beyond Vietnam. Nevertheless, by 1969, he was beginning troop withdrawals from Vietnam while simultaneously looking for a “knockout blow” against the North Vietnamese. In sum, the Nixon administration was in need of an exit strategy.
The escalation of the war, however, made an easy withdrawal increasingly difficult. Officially, the United States was the ally and partner of the South Vietnamese, whose “hearts and minds” it was trying to win through a combination of military assistance and economic development. In reality, however, U.S. soldiers, who found themselves fighting in an inhospitable environment thousands of miles from home to protect people who often resented their presence and aided their enemies, came to regard the Vietnamese as backward, cowardly people and the government of South Vietnam as hopelessly inefficient and corrupt. Instead of winning “hearts and minds,” U.S. warfare in Vietnam cost the lives and limbs of U.S. troops and millions of Vietnamese combatants and civilians ().
For their part, the North Vietnamese forces and the National Liberation Front in South Vietnam also used brutal tactics to terrorize and kill their opponents or effectively control their territory. Political assassinations and forced indoctrination were common. Captured U.S. soldiers frequently endured torture and imprisonment.
### MY LAI
Racism on the part of some U.S. soldiers and a desire to retaliate against those they perceived to be responsible for harming U.S. troops affected the conduct of the war. A war correspondent who served in Vietnam noted, “In motivating the GI to fight by appealing to his racist feelings, the United States military discovered that it had liberated an emotion over which it was to lose control.” It was not unusual for U.S. soldiers to evacuate and burn villages suspected of shielding Viet Cong fighters, both to deprive the enemy of potential support and to enact revenge for enemy brutality. Troops shot at farmers’ water buffalo for target practice. American and South Vietnamese use of napalm, a jellied gasoline that sticks to the objects it burns, was common. Originally developed to burn down structures during World War II, in Vietnam, it was directed against human beings as well, as had occurred during the Korean War.
On March 16, 1968, men from the U.S. Army’s Twenty-Third Infantry Division committed one of the most notorious atrocities of the war. About one hundred soldiers commanded by Captain Ernest Medina were sent to destroy the village of My Lai, which was suspected of hiding Viet Cong fighters. Although there was later disagreement regarding the captain’s exact words, the platoon leaders believed the order to destroy the enemy included killing women and children. Having suffered twenty-eight casualties in the past three months, the men of Charlie Company were under severe stress and extremely apprehensive as they approached the village. Two platoons entered it, shooting randomly. A group of seventy to eighty unarmed people, including children and infants, were forced into an irrigation ditch by members of the First Platoon under the command of Lt. William L. Calley, Jr. Despite their proclamations of innocence, the villagers were shot (). Houses were set on fire, and as the inhabitants tried to flee, they were killed with rifles, machine guns, and grenades. The U.S. troops were never fired upon, and one soldier later testified that he did not see any man who looked like a Viet Cong fighter.
The precise number of civilians killed that day is unclear: The numbers range from 347 to 504. None were armed. Although not all the soldiers in My Lai took part in the killings, no one attempted to stop the massacre before the arrival by helicopter of Warrant Officer Hugh Thompson, who, along with his crew, attempted to evacuate women and children. Upon returning to his base, Thompson immediately reported the events taking place at My Lai. Shortly thereafter, Medina ordered Charlie Company to cease fire. Although Thompson’s crewmembers confirmed his account, none of the men from Charlie Company gave a report, and a cover-up began almost immediately. The army first claimed that 150 people, the majority of them Viet Cong, had been killed during a firefight with Charlie Company.
Hearing details from friends in Charlie Company, a helicopter gunner by the name of Ron Ridenhour began to conduct his own investigation and, in April 1969, wrote to thirty members of Congress, demanding an investigation. By September 1969, the army charged Lt. Calley with premeditated murder. Many Americans were horrified at the graphic footage of the massacre; the incident confirmed their belief that the war was unjust and not being fought on behalf of the Vietnamese people. However, nearly half of the respondents to a Minnesota poll did not believe that the incident at My Lai had actually happened. U.S. soldiers could not possibly do such horrible things, they felt; they were certain that American goals in Vietnam were honorable and speculated that the antiwar movement had concocted the story to generate sympathy for the enemy.
Calley was found guilty in March 1971, and sentenced to life in prison. Nationwide, hundreds of thousands of Americans joined a “Free Calley” campaign. Two days later, President Nixon released him from custody and placed him under him house arrest at Fort Benning, Georgia. In August of that same year, Calley’s sentence was reduced to twenty years, and in September 1974, he was paroled. The only soldier convicted in the massacre, he spent a total of three-and-a-half years under house arrest for his crimes.
### BATTLES AT HOME
As the conflict wore on and reports of brutalities increased, the antiwar movement grew in strength. To take the political pressure off himself and his administration, and find a way to exit Vietnam “with honor,” Nixon began the process of Vietnamization, turning more responsibility for the war over to South Vietnamese forces by training them and providing American weaponry, while withdrawing U.S. troops from the field. At the same time, however, Nixon authorized the bombing of neighboring Cambodia, which had declared its neutrality, in an effort to destroy North Vietnamese and Viet Cong bases within that country and cut off supply routes between North and South Vietnam. The bombing was kept secret from both Congress and the American public. In April 1970, Nixon decided to follow up with an invasion of Cambodia.
The invasion could not be kept secret, and when Nixon announced it on television on April 30, 1970, protests sprang up across the country. The most tragic and politically damaging occurred on May 1, 1970, at Kent State University in Ohio. Violence erupted in the town of Kent after an initial student demonstration on campus, and the next day, the mayor asked Ohio’s governor to send in the National Guard. Troops were sent to the university’s campus, where students had set fire to the ROTC building and were fighting off firemen and policemen trying to extinguish it. The National Guard used teargas to break up the demonstration, and several students were arrested ().
Tensions came to a head on May 4. Although campus officials had called off a planned demonstration, some fifteen hundred to two thousand students assembled, throwing rocks at a security officer who ordered them to leave. Seventy-seven members of the National Guard, with bayonets attached to their rifles, approached the students. After forcing most of them to retreat, the troops seemed to depart. Then, for reasons that are still unknown, they halted and turned; many began to fire at the students. Nine students were wounded; four were killed. Two of the dead had simply been crossing campus on their way to class. Peace was finally restored when a faculty member pleaded with the remaining students to leave.
News of the Kent State shootings shocked students around the country. Millions refused to attend class, as strikes were held at hundreds of colleges and high schools across the United States. On May 8, an antiwar protest took place in New York City, and the next day, 100,000 protesters assembled in Washington, DC. Not everyone sympathized with the slain students, however. Nixon had earlier referred to student demonstrators as “bums,” and construction workers attacked the New York City protestors. A Gallup poll revealed that most Americans blamed the students for the tragic events at Kent State.
On May 15, a similar tragedy took place at Jackson State College, an African American college in Jackson, Mississippi. Once again, students gathered on campus to protest the invasion of Cambodia, setting fires and throwing rocks. The police arrived to disperse the protesters, who had gathered outside a women’s dormitory. Shortly after midnight, the police opened fire with shotguns. The dormitory windows shattered, showering people with broken glass. Twelve were wounded, and two young men, one a student at the college and the other a local high school student, were killed.
### PULLING OUT OF THE QUAGMIRE
Ongoing protests, campus violence, and the expansion of the war into Cambodia deeply disillusioned Americans about their role in Vietnam. Understanding the nation’s mood, Nixon dropped his opposition to a repeal of the Gulf of Tonkin Resolution of 1964. In January 1971, he signed Congress’s revocation of the notorious blanket military authorization. Gallup polls taken in May of that year revealed that only 28 percent of the respondents supported the war; many felt it was not only a mistake but also immoral.
Just as influential as antiwar protests and campus violence in turning people against the war was the publication of documents the media dubbed the Pentagon Papers in June 1971. These were excerpts from a study prepared during the Johnson administration that revealed the true nature of the conflict in Vietnam. The public learned for the first time that the United States had been planning to oust Ngo Dinh Diem from the South Vietnamese government, that Johnson meant to expand the U.S. role in Vietnam and bomb North Vietnam even as he stated publicly that he had no intentions of doing so, and that his administration had sought to deliberately provoke North Vietnamese attacks in order to justify escalating American involvement. Copies of the study had been given to the New York Times and other newspapers by Daniel Ellsberg, one of the military analysts who had contributed to it. To avoid setting a precedent by allowing the press to publish confidential documents, Nixon’s attorney general, John Mitchell, sought an injunction against the New York Times to prevent its publication of future articles based on the Pentagon Papers. The newspaper appealed. On June 30, 1971, the U.S. Supreme Court held that the government could not prevent the publication of the articles.
Realizing that he must end the war but reluctant to make it look as though the United States was admitting its failure to subdue a small Asian nation, Nixon began maneuvering to secure favorable peace terms from the North Vietnamese. Thanks to his diplomatic efforts in China and the Soviet Union, those two nations cautioned North Vietnam to use restraint. The loss of strong support by their patrons, together with intensive bombing of Hanoi and the mining of crucial North Vietnamese harbors by U.S. forces, made the North Vietnamese more willing to negotiate.
Nixon’s actions had also won him popular support at home. By the 1972 election, voters again favored his Vietnam policy by a ratio of two to one. On January 27, 1973, Secretary of State Henry Kissinger signed an accord with Le Duc Tho, the chief negotiator for the North Vietnamese, ending American participation in the war. The United States was given sixty days to withdraw its troops, and North Vietnam was allowed to keep its forces in places it currently occupied. This meant that over 100,000 northern soldiers would remain in the South—ideally situated to continue the war with South Vietnam. The United States left behind a small number of military advisors as well as equipment, and Congress continued to approve funds for South Vietnam, but considerably less than in earlier years. So the war continued, but it was clear the South could not hope to defeat the North.
As the end was nearing, the United States conducted several operations to evacuate children from the South. On the morning of April 29, 1975, as North Vietnamese and Viet Cong forces moved through the outskirts of Saigon, orders were given to evacuate Americans and South Vietnamese who had supported the United States. Unable to use the airport, helicopters ferried Americans and Vietnamese refugees who had fled to the American embassy to ships off the coast. North Vietnamese forces entered Saigon the next day, and the South surrendered.
The war had cost the lives of more than 1.5 million Vietnamese combatants and civilians, as well as over 58,000 U.S. troops. But the war had caused another, more intangible casualty: the loss of consensus, confidence, and a sense of moral high ground in the American political culture.
### Section Summary
As the war in Vietnam raged on, Americans were horrified to hear of atrocities committed by U.S. soldiers, such as the 1968 massacre of villagers at My Lai. To try to end the conflict, Nixon escalated it by bombing Hanoi and invading Cambodia; his actions provoked massive antiwar demonstrations in the United States that often ended in violence, such as the tragic shooting of unarmed student protestors at Kent State University in 1970. The 1971 release of the Pentagon Papers revealed the true nature of the war to an increasingly disapproving and disenchanted public. Secretary of State Henry Kissinger eventually drafted a peace treaty with North Vietnam, and, after handing over responsibility for the war to South Vietnam, the United States withdrew its troops in 1973. South Vietnam surrendered to the North two years later.
### Review Questions
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# Political Storms at Home and Abroad, 1968-1980
## Watergate: Nixon’s Domestic Nightmare
Feeling the pressure of domestic antiwar sentiment and desiring a decisive victory, Nixon went into the 1972 reelection season having attempted to fashion a “new majority” of moderate southerners and northern, working-class White people. The Democrats, responding to the chaos and failings of the Chicago convention, had instituted new rules on how delegates were chosen, which they hoped would broaden participation and the appeal of the party. Nixon proved unbeatable, however. Even evidence that his administration had broken the law failed to keep him from winning the White House.
### THE ELECTION OF 1972
Following the 1968 nominating convention in Chicago, the process of selecting delegates for the Democratic National Convention was redesigned. The new rules, set by a commission led by George McGovern, awarded delegates based on candidates’ performance in state primaries (). As a result, a candidate who won no primaries could not receive the party’s nomination, as Hubert Humphrey had done in Chicago. This system gave a greater voice to people who voted in the primaries and reduced the influence of party leaders and power brokers.
It also led to a more inclusive political environment in which Shirley Chisholm received 156 votes for the Democratic nomination on the first ballot (). Eventually, the nomination went to George McGovern, a strong opponent of the Vietnam War. Many Democrats refused to support his campaign, however. Working- and middle-class voters turned against him too after allegations that he supported women’s right to an abortion and the decriminalization of drug use. McGovern’s initial support of vice presidential candidate Thomas Eagleton in the face of revelations that Eagleton had undergone electroshock treatment for depression, followed by his withdrawal of that support and acceptance of Eagleton’s resignation, also made McGovern look indecisive and unorganized.
Nixon and the Republicans led from the start. To increase their advantage, they attempted to paint McGovern as a radical leftist who favored amnesty for draft dodgers. In the Electoral College, McGovern carried only Massachusetts and Washington, DC. Nixon won a decisive victory of 520 electoral votes to McGovern’s 17. One Democrat described his role in McGovern’s campaign as “recreation director on the Titanic.”
### HIGH CRIMES AND MISDEMEANORS
Nixon’s victory over a Democratic party in disarray was the most remarkable landslide since Franklin D. Roosevelt’s reelection in 1936. But Nixon’s victory was short-lived, however, for it was soon discovered that he and members of his administration had routinely engaged in unethical and illegal behavior during his first term. Following the publication of the Pentagon Papers, for instance, the “plumbers,” a group of men used by the White House to spy on the president’s opponents and stop leaks to the press, broke into the office of Daniel Ellsberg’s psychiatrist to steal Ellsberg’s file and learn information that might damage his reputation.
During the presidential campaign, the Committee to Re-Elect the President (CREEP) decided to play “dirty tricks” on Nixon’s opponents. Before the New Hampshire Democratic primary, a forged letter supposedly written by Democratic-hopeful Edmund Muskie in which he insulted French Canadians, one of the state’s largest ethnic groups, was leaked to the press. Men were assigned to spy on both McGovern and Senator Edward Kennedy. One of them managed to masquerade as a reporter on board McGovern’s press plane. Men pretending to work for the campaigns of Nixon’s Democratic opponents contacted vendors in various states to rent or purchase materials for rallies; the rallies were never held, of course, and Democratic politicians were accused of failing to pay the bills they owed.
CREEP’s most notorious operation, however, was its break-in at the offices of the Democratic National Committee (DNC) in the Watergate office complex in Washington, DC, as well as its subsequent cover-up. On the evening of June 17, 1972, the police arrested five men inside DNC headquarters (). According to a plan originally proposed by CREEP’s general counsel and White House plumber G. Gordon Liddy, the men were to wiretap DNC telephones. The FBI quickly discovered that two of the men had E. Howard Hunt’s name in their address books. Hunt was a former CIA officer and also one of the plumbers. In the following weeks, yet more connections were found between the burglars and CREEP, and in October 1972, the FBI revealed evidence of illegal intelligence gathering by CREEP for the purpose of sabotaging the Democratic Party. Nixon won his reelection handily in November. Had the president and his reelection team not pursued a strategy of dirty tricks, Richard Nixon would have governed his second term with one of the largest political leads in the twentieth century.
In the weeks following the Watergate break-in, Bob Woodward and Carl Bernstein, reporters for The Washington Post, received information from several anonymous sources, including one known to them only as “Deep Throat,” that led them to realize the White House was deeply implicated in the break-in. As the press focused on other events, Woodward and Bernstein continued to dig and publish their findings, keeping the public’s attention on the unfolding scandal. Years later, Deep Throat was revealed to be Mark Felt, then the FBI’s associate director.
### THE WATERGATE CRISIS
Initially, Nixon was able to hide his connection to the break-in and the other wrongdoings alleged against members of CREEP. However, by early 1973, the situation quickly began to unravel. In January, the Watergate burglars were convicted, along with Hunt and Liddy. Trial judge John Sirica was not convinced that all the guilty had been discovered. In February, confronted with evidence that people close to the president were connected to the burglary, the Senate appointed the Watergate Committee to investigate. Ten days later, in his testimony before the Senate Judiciary Committee, L. Patrick Gray, acting director of the FBI, admitted destroying evidence taken from Hunt’s safe by John Dean, the White House counsel, after the burglars were caught.
On March 23, 1973, Judge Sirica publicly read a letter from one of the Watergate burglars, alleging that perjury had been committed during the trial. Less than two weeks later, Jeb Magruder, a deputy director of CREEP, admitted lying under oath and indicated that Dean and John Mitchell, who had resigned as attorney general to become the director of CREEP, were also involved in the break-in and its cover-up. Dean confessed, and on April 30, Nixon fired him and requested the resignation of his aides John Ehrlichman and H. R. Haldeman, also implicated. To defuse criticism and avoid suspicion that he was participating in a cover-up, Nixon also announced the resignation of the current attorney general, Richard Kleindienst, a close friend, and appointed Elliott Richardson to the position. In May 1973, Richardson named Archibald Cox special prosecutor to investigate the Watergate affair.
Throughout the spring and the long, hot summer of 1973, Americans sat glued to their television screens, as the major networks took turns broadcasting the Senate hearings. One by one, disgraced former members of the administration confessed, or denied, their role in the Watergate scandal. Dean testified that Nixon was involved in the conspiracy, allegations the president denied. In March 1974, Haldeman, Ehrlichman, and Mitchell were indicted and charged with conspiracy.
Without evidence clearly implicating the president, the investigation might have ended if not for the testimony of Alexander Butterfield, a low-ranking member of the administration, that a voice-activated recording system had been installed in the Oval Office. The President’s most intimate conversations had been caught on tape. Cox and the Senate subpoenaed them.
Nixon, however, refused to hand the tapes over and cited executive privilege, the right of the president to refuse certain subpoenas. When he offered to supply summaries of the conversations, Cox refused. On October 20, 1973, in an event that became known as the Saturday Night Massacre, Nixon ordered Attorney General Richardson to fire Cox. Richardson refused and resigned, as did Deputy Attorney General William Ruckelshaus when confronted with the same order. Control of the Justice Department then fell to Solicitor General Robert Bork, who complied with Nixon’s order. In December, the House Judiciary Committee began its own investigation to determine whether there was enough evidence of wrongdoing to impeach the president.
The public was enraged by Nixon’s actions. A growing number of citizens felt as though the president had placed himself above the law. Telegrams flooded the White House. The House of Representatives began to discuss impeachment. In April 1974, when Nixon agreed to release transcripts of the tapes, it was too little, too late (). Yet, while revealing nothing about Nixon’s knowledge of Watergate, the transcripts captured Nixon in a most unflattering light and helped to dismantle the image of himself he had so carefully curated over his years of public service.
At the end of its hearings, in July 1974, the House Judiciary Committee voted to pass three of the five articles of impeachment out of committee. However, before the full House could vote, the U.S. Supreme Court ordered Nixon to release the actual tapes of his conversations, not just transcripts or summaries. One of the tapes revealed that he had in fact been told about White House involvement in the Watergate break-in shortly after it occurred. In a speech on August 5, 1974, Nixon, pleading a poor memory, accepted blame for the Watergate scandal. Warned by other Republicans that he would be found guilty by the Senate and removed from office, he resigned the presidency on August 8.
Nixon’s resignation, which took effect the next day, did not make the Watergate scandal vanish. Instead, it fed a growing suspicion of government felt by many. The events of Vietnam had already showed that the government could not be trusted to protect the interests of the people or tell them the truth. For many, Watergate confirmed these beliefs, and the suffix “-gate” attached to a word has since come to mean a political scandal.
### FORD NOT A LINCOLN
When Gerald R. Ford took the oath of office on August 9, 1974, he understood that his most pressing task was to help the country move beyond the Watergate scandal. His declaration that “Our long national nightmare is over. . . . [O]ur great Republic is a government of laws and not of men” was met with almost universal applause.
It was indeed an unprecedented time. Ford was the first vice president chosen under the terms of the Twenty-Fifth Amendment, which provides for the appointment of a vice president in the event the incumbent dies or resigns; Nixon had appointed Ford, a longtime House representative from Michigan known for his honesty, following the resignation of embattled vice president Spiro T. Agnew over a charge of failing to report income—a lenient charge since this income stemmed from bribes he had received as the governor of Maryland. Ford was also the first vice president to take office after a sitting president’s resignation, and the only chief executive never elected either president or vice president. One of his first actions as president was to grant Richard Nixon a full pardon (). Ford thus prevented Nixon’s indictment for any crimes he may have committed in office and ended criminal investigations into his actions. The public reacted with suspicion and outrage. Many were convinced that the extent of Nixon’s wrongdoings would now never been known and he would never be called to account for them. When Ford chose to run for the presidency in 1976, the pardon returned to haunt him.
As president, Ford confronted monumental issues, such as inflation, a depressed economy, and chronic energy shortages. He established his policies during his first year in office, despite opposition from a heavily Democratic Congress. In October 1974, he labeled inflation the country’s most dangerous public enemy and sought a grassroots campaign to curtail it by encouraging people to be disciplined in their consuming habits and increase their savings. The campaign was titled “Whip Inflation Now” and was advertised on brightly colored “Win” buttons volunteers were to wear. When recession became the nation’s most serious domestic problem, Ford shifted to measures aimed at stimulating the economy. Still fearing inflation, however, he vetoed a number of nonmilitary appropriations bills that would have increased the already-large budget deficit.
Ford’s economic policies ultimately proved unsuccessful. Because of opposition from a Democratic Congress, his foreign policy accomplishments were also limited. When he requested money to assist the South Vietnamese government in its effort to repel North Vietnamese forces, Congress refused. Ford was more successful in other parts of the world. He continued Nixon’s policy of détente with the Soviet Union, and he and Secretary of State Kissinger achieved further progress in the second round of SALT talks. In August 1975, Ford went to Finland and signed the Helsinki Accords with Soviet premier Leonid Brezhnev. This agreement essentially accepted the territorial boundaries that had been established at the end of World War II in 1945. It also exacted a pledge from the signatory nations that they would protect human rights within their countries. Many immigrants to the United States protested Ford’s actions, because it seemed as though he had accepted the status quo and left their homelands under Soviet domination. Others considered it a belated American acceptance of the world as it really was.
### Section Summary
In 1972, President Nixon faced an easy reelection against a Democratic Party in disarray. But even before his landslide victory, evidence had surfaced that the White House was involved in the break-in at the DNC’s headquarters at the Watergate office complex. As the investigation unfolded, the depths to which Nixon and his advisers had sunk became clear. Some twenty-five of Nixon’s aides were indicted for criminal activity, and he faced impeachment before becoming the first president to resign from office. His successor, Gerald Ford, was unable to solve the pressing problems the United States faced or erase the stain of Watergate.
### Review Questions
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# Political Storms at Home and Abroad, 1968-1980
## Jimmy Carter in the Aftermath of the Storm
At his inauguration in January 1977, President Jimmy Carter began his speech by thanking outgoing president Gerald Ford for all he had done to “heal” the scars left by Watergate. American gratitude had not been great enough to return Ford to the Oval Office, but enthusiasm for the new president was not much greater in the new atmosphere of disillusionment with political leaders. Indeed, Carter won his party’s nomination and the presidency largely because the Democratic leadership had been decimated by assassination and the taint of Vietnam, and he had carefully positioned himself as an outsider who could not be blamed for current policies. Ultimately, Carter’s presidency proved a lackluster one that was marked by economic stagnation at home and humiliation overseas.
### THE ELECTION OF 1976
President Ford won the Republican nomination for the presidency in 1976, narrowly defeating former California governor Ronald Reagan, but he lost the election to his Democratic opponent Jimmy Carter. Carter ran on an “anti-Washington” ticket, making a virtue of his lack of experience in what was increasingly seen as the corrupt politics of the nation’s capital. Accepting his party’s nomination, the former governor of Georgia pledged to combat racism and sexism as well as overhaul the tax structure. He openly proclaimed his faith as a born-again Christian and promised to change the welfare system and provide comprehensive healthcare coverage for neglected citizens who deserved compassion. Most importantly, Jimmy Carter promised that he would “never lie.”
Ford’s pardon of Richard Nixon had alienated many Republicans. That, combined with the stagnant economy, cost him votes, and Jimmy Carter, an engineer and former naval officer who portrayed himself as a humble peanut farmer, prevailed, carrying all the southern states, except Virginia and Oklahoma (). Ford did well in the West, but Carter received 50 percent of the popular vote to Ford’s 48 percent, and 297 electoral votes to Ford’s 240.
### ON THE INSIDE
Making a virtue of his lack of political experience, especially in Washington, Jimmy Carter took office with less practical experience in executive leadership and the workings of the national government than any president since Calvin Coolidge. His first executive act was to fulfill a campaign pledge to grant unconditional amnesty to young men who had evaded the draft during the Vietnam War. Despite the early promise of his rhetoric, within a couple of years of his taking office, liberal Democrats claimed Carter was the most conservative Democratic president since Grover Cleveland.
In trying to manage the relatively high unemployment rate of 7.5 percent and inflation that had risen into the double digits by 1978, Carter was only marginally effective. His tax reform measure of 1977 was weak and failed to close the grossest of loopholes. His deregulation of major industries, such as aviation and trucking, was intended to force large companies to become more competitive. Consumers benefited in some ways: For example, airlines offered cheaper fares to beat their competitors. However, some companies, like Pan American World Airways, instead went out of business. Carter also expanded various social programs, improved housing for the elderly, and took steps to improve workplace safety.
Because the high cost of fuel continued to hinder economic expansion, the creation of an energy program became a central focus of his administration. Carter stressed energy conservation, encouraging people to insulate their houses and rewarding them with tax credits if they did so, and pushing for the use of coal, nuclear power, and alternative energy sources such as solar power to replace oil and natural gas. To this end, Carter created the Department of Energy.
### CARTER AND A NEW DIRECTION IN FOREIGN AFFAIRS
Carter believed that U.S. foreign policy should be founded upon deeply held moral principles and national values. The mission in Vietnam had failed, he argued, because American actions there were contrary to moral values. His dedication to peace and human rights significantly changed the way that the United States conducted its foreign affairs. He improved relations with China, ended military support to Nicaraguan dictator Anastasio Somoza, and helped arrange for the Panama Canal to be returned to Panamanian control in 1999. He agreed to a new round of talks with the Soviet Union (SALT II) and brought Israeli prime minister Menachem Begin and Egyptian president Anwar Sadat to the United States to discuss peace between their countries. Their meetings at Camp David, the presidential retreat in Maryland, led to the signing of the Camp David Accords in September 1978 (). This in turn resulted in the drafting of a historic peace treaty between Egypt and Israel in 1979.
Despite achieving many successes in the area of foreign policy, Carter made a more controversial decision in response to the Soviet Union’s 1979 invasion of Afghanistan. In January 1980, he declared that if the USSR did not withdraw its forces, the United States would boycott the 1980 Summer Olympic Games in Moscow. The Soviets did not retreat, and the United States did not send a team to Moscow. Only about half of the American public supported this decision, and despite Carter’s call for other countries to join the boycott, very few did so.
### HOSTAGES TO HISTORY
Carter’s biggest foreign policy problem was the Iranian hostage crisis, whose roots lay in the 1950s. In 1953, the United States had assisted Great Britain in the overthrow of Prime Minister Mohammad Mossadegh, a rival of Mohammad Reza Pahlavi, the shah of Iran. Mossadegh had sought greater Iranian control over the nation’s oil wealth, which was claimed by British companies. Following the coup, the shah assumed complete control of Iran’s government. He then disposed of political enemies and eliminated dissent through the use of SAVAK, a secret police force trained by the United States. The United States also supplied the shah’s government with billions of dollars in aid. As Iran’s oil revenue grew, especially after the 1973 oil embargo against the United States, the pace of its economic development and the size of its educated middle class also increased, and the country became less dependent on U.S. aid. Its population increasingly blamed the United States for the death of Iranian democracy and faulted it for its consistent support of Israel.
Despite the shah’s unpopularity among his own people, the result of both his brutal policies and his desire to Westernize Iran, the United States supported his regime. In February 1979, the shah was overthrown when revolution broke out, and a few months later, he departed for the United States for medical treatment. The long history of U.S. support for him and its offer of refuge greatly angered Iranian revolutionaries. On November 4, 1979, a group of Iranian students and activists, including Islamic fundamentalists who wished to end the Westernization and secularization of Iran, invaded the American embassy in Tehran and seized sixty-six embassy employees. The women and African Americans were soon released, leaving fifty-three men as hostages. Negotiations failed to free them, and in April 1980, a rescue attempt fell through when the aircraft sent to transport them crashed. Another hostage was released when he developed serious medical problems. President Carter’s inability to free the other captives hurt his performance in the 1980 elections. The fifty-two men still held in Iran were finally freed on January 20, 1981, the day Ronald Reagan took office as president ().
Carter’s handling of the crisis appeared even less effective in the way the media portrayed it publicly. This contributed to a growing sense of malaise, a feeling that the United States’ best days were behind it and the country had entered a period of decline. This belief was compounded by continuing economic problems, and the oil shortage and subsequent rise in prices that followed the Iranian Revolution. The president’s decision to import less oil to the United States and remove price controls on oil and gasoline did not help matters. In 1979, Carter sought to reassure the nation and the rest of the world, especially the Soviet Union, that the United States was still able to defend its interests. To dissuade the Soviets from making additional inroads in southwest Asia, he proposed the Carter Doctrine, which stated that the United States would regard any attempt to interfere with its interests in the Middle East as an act of aggression to be met with force if necessary.
Carter had failed to solve the nation’s problems. Some blamed these problems on dishonest politicians; others blamed the problems on the Cold War obsession with fighting Communism, even in small nations like Vietnam that had little influence on American national interests. Still others faulted American materialism. In 1980, a small but growing group called the Moral Majority faulted Carter for betraying his southern roots and began to seek a return to traditional values.
### Section Summary
Jimmy Carter’s administration began with great promise, but his efforts to improve the economy through deregulation largely failed. Carter’s attempt at a foreign policy built on the principle of human rights also prompted much criticism, as did his decision to boycott the Summer Olympics in Moscow. On the other hand, he successfully brokered the beginnings of a historic peace treaty between Egypt and Israel. Remaining public faith in Carter was dealt a serious blow, however, when he proved unable to free the American hostages in Tehran.
### Review Questions
### Critical Thinking Questions
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# From Cold War to Culture Wars, 1980-2000
## Introduction
“Act up!” might be called the unofficial slogan of the 1980s. Numerous groups were concerned by what they considered disturbing social, cultural, and political trends in the United States and lobbied for their vision of what the nation should be. Conservative politicians cut taxes for the wealthy and shrank programs for the poor, while conservative Christians blamed the legalization of abortion and the increased visibility of gays and lesbians for weakening the American family. When the U.S. Centers for Disease Control first recognized the Acquired Immune Deficiency Syndrome (AIDS) in 1981, the Religious Right regarded it as a plague sent by God to punish gay men for their “unnatural” behavior. Politicians, many of whom relied on religious conservatives for their votes, largely ignored the AIDS epidemic. In response, organizations such as ACT UP were formed to draw attention to their cause ().
Toward the end of the decade in 1989, protesters from both East and West Berlin began “acting up” and tearing down large chunks of the Berlin Wall, essentially dismantling the Iron Curtain. This symbolic act was the culmination of earlier demonstrations that had swept across Eastern Europe, resulting in the collapse of Communist governments in both Central and Eastern Europe, and marking the beginning of the end of the Cold War. |
# From Cold War to Culture Wars, 1980-2000
## The Reagan Revolution
Ronald Reagan entered the White House in 1981 with strongly conservative values but experience in moderate politics. He appealed to moderates and conservatives anxious about social change and the seeming loss of American power and influence on the world stage. Leading the so-called Reagan Revolution, he appealed to voters with the promise that the principles of conservatism could halt and revert the social and economic changes of the last generation. Reagan won the White House by citing big government and attempts at social reform as the problem, not the solution. He was able to capture the political capital of an unsettled national mood and, in the process, helped set an agenda and policies that would affect his successors and the political landscape of the nation.
### REAGAN’S EARLY CAREER
Although many of his movie roles and the persona he created for himself seemed to represent traditional values, Reagan’s rise to the presidency was an unusual transition from pop cultural significance to political success. Born and raised in the Midwest, he moved to California in 1937 to become a Hollywood actor. He also became a reserve officer in the U.S. Army that same year, but when the country entered World War II, he was excluded from active duty overseas because of poor eyesight and spent the war in the army’s First Motion Picture Unit. After the war, he resumed his film career; rose to leadership in the Screen Actors Guild, a Hollywood union; and became a spokesman for General Electric and the host of a television series that the company sponsored. As a young man, he identified politically as a liberal Democrat, but his distaste for communism, along with the influence of the social conservative values of his second wife, actress Nancy Davis, edged him closer to conservative Republicanism (). By 1962, he had formally switched political parties, and in 1964, he actively campaigned for the Republican presidential nominee Barry Goldwater.
Reagan launched his own political career in 1966 when he successfully ran for governor of California. His opponent was the incumbent Pat Brown, a liberal Democrat who had already served two terms. Reagan, quite undeservedly, blamed Brown for race riots in California and student protests at the University of California at Berkeley. He criticized the Democratic incumbent’s increases in taxes and state government, and denounced “big government” and the inequities of taxation in favor of free enterprise. As governor, however, he quickly learned that federal and state laws prohibited the elimination of certain programs and that many programs benefited his constituents. He ended up approving the largest budget in the state’s history and approved tax increases on a number of occasions. The contrast between Reagan’s rhetoric and practice made up his political skill: capturing the public mood and catering to it, but compromising when necessary.
### REPUBLICANS BACK IN THE WHITE HOUSE
After two unsuccessful Republican primary bids in 1968 and 1976, Reagan won the presidency in 1980. His victory was the result of a combination of dissatisfaction with the presidential leadership of Gerald Ford and Jimmy Carter in the 1970s and the growth of the New Right. This group of conservative Americans included many very wealthy financial supporters and emerged in the wake of the social reforms and cultural changes of the 1960s and 1970s. Many were evangelical Christians, like those who joined Jerry Falwell’s Moral Majority, and opposed the legalization of abortion, the feminist movement, and sex education in public schools. Reagan also attracted people, often dubbed neoconservatives, who would not previously have voted for the same candidate as conservative Protestants did. Many were middle- and working-class people who resented the growth of federal and state governments, especially benefit programs, and the subsequent increase in taxes during the late 1960s and 1970s. They favored the tax revolts that swept the nation in the late 1970s under the leadership of predominantly older, White, middle-class Americans, which had succeeded in imposing radical reductions in local property and state income taxes.
Voter turnout reflected this new conservative swing, which not only swept Reagan into the White House but created a Republican majority in the Senate. Only 52 percent of eligible voters went to the polls in 1980, the lowest turnout for a presidential election since 1948. Those who did cast a ballot were older, Whiter, and wealthier than those who did not vote (). Strong support among White voters, those over forty-five years of age, and those with incomes over $50,000 proved crucial for Reagan’s victory.
### REAGANOMICS
Reagan’s primary goal upon taking office was to stimulate the sagging economy while simultaneously cutting both government programs and taxes. His economic policies, called Reaganomics by the press, were based on a theory called supply-side economics, about which many economists were skeptical. Influenced by economist Arthur Laffer of the University of Southern California, Reagan cut income taxes for those at the top of the economic ladder, which was supposed to motivate the rich to invest in businesses, factories, and the stock market in anticipation of high returns. According to Laffer’s argument, this would eventually translate into more jobs further down the socioeconomic ladder. Economic growth would also increase the total tax revenue—even at a lower tax rate. In other words, proponents of “trickle-down economics” promised to cut taxes and balance the budget at the same time. Reaganomics also included the deregulation of industry and higher interest rates to control inflation, but these initiatives preceded Reagan and were conceived in the Carter administration.
Many politicians, including Republicans, were wary of Reagan’s economic program; even his eventual vice president, George H. W. Bush, had referred to it as “voodoo economics” when competing with him for the Republican presidential nomination. When Reagan proposed a 30 percent cut in taxes to be phased in over his first term in office, Congress balked. Opponents argued that the tax cuts would benefit the rich and not the poor, who needed help the most. In response, Reagan presented his plan directly to the people ().
Reagan was an articulate spokesman for his political perspectives and was able to garner support for his policies. Often called “The Great Communicator,” he was noted for his ability, honed through years as an actor and spokesperson, to convey a mixture of folksy wisdom, empathy, and concern while taking humorous digs at his opponents. Indeed, listening to Reagan speak often felt like hearing a favorite uncle recall stories about the “good old days” before big government, expensive social programs, and greedy politicians destroyed the country (). Americans found this rhetorical style extremely compelling. Public support for the plan, combined with a surge in the president’s popularity after he survived an assassination attempt in March 1981, swayed Congress, including many Democrats. On July 29, 1981, Congress passed the Economic Recovery Tax Act, which phased in a 25 percent overall reduction in taxes over a period of three years.
Reagan was successful at cutting taxes, but he failed to reduce government spending. Although he had long warned about the dangers of big government, he created a new cabinet-level agency, the Department of Veterans Affairs, and the number of federal employees increased during his time in office. He allocated a smaller share of the federal budget to antipoverty programs like Aid to Families with Dependent Children (AFDC), food stamps, rent subsidies, job training programs, and Medicaid, but Social Security and Medicare entitlements, from which his supporters benefited, were left largely untouched except for an increase in payroll taxes to pay for them. Indeed, in 1983, Reagan agreed to a compromise with the Democrats in Congress on a $165 billion injection of funds to save Social Security, which included this payroll tax increase.
But Reagan seemed less flexible when it came to deregulating industry and weakening the power of labor unions. Banks and savings and loan associations were deregulated. Pollution control was enforced less strictly by the Environmental Protection Agency, and restrictions on logging and drilling for oil on public lands were relaxed. Believing the free market was self-regulating, the Reagan administration had little use for labor unions, and in 1981, the president fired twelve thousand federal air traffic controllers who had gone on strike to secure better working conditions (which would also have improved the public’s safety). His action effectively destroyed the Professional Air Traffic Controllers Organization (PATCO) and ushered in a new era of labor relations in which, following his example, employers simply replaced striking workers. The weakening of unions contributed to the leveling off of real wages for the average American family during the 1980s.
Reagan’s economic policymakers succeeded in breaking the cycle of stagflation that had been plaguing the nation, but at significant cost. In its effort to curb high inflation with dramatically increased interest rates, the Federal Reserve also triggered a deep recession. Inflation did drop, but borrowing became expensive and consumers spent less. In Reagan’s first years in office, bankruptcies increased and unemployment reached about 10 percent, its highest level since the Great Depression. Homelessness became a significant problem in cities, a fact the president made light of by suggesting that the press exaggerated the problem and that many homeless people chose to live on the streets. Economic growth resumed in 1983 and gross domestic product grew at an average of 4.5 percent during the rest of his presidency. By the end of Reagan’s second term in office, unemployment had dropped to about 5.3 percent, but the nation was nearly $3 trillion in debt. An increase in defense spending coupled with $3.6 billion in tax relief for the 162,000 American families with incomes of $200,000 or more made a balanced budget, one of the president’s campaign promises in 1980, impossible to achieve.
The Reagan years were a complicated era of social, economic, and political change, with many trends operating simultaneously and sometimes at cross-purposes. While many suffered, others prospered. The 1970s had been the era of the hippie, and Newsweek magazine declared 1984 to be the “year of the Yuppie.” Yuppies, whose name derived from “(y)oung, (u)rban (p)rofessionals,” were akin to hippies in being young people whose interests, values, and lifestyle influenced American culture, economy, and politics, just as the hippies’ credo had done in the late 1960s and 1970s. Unlike hippies, however, yuppies were viewed as being materialistic and obsessed with image, comfort, and economic prosperity. Although liberal on some social issues, economically they were conservative. Ironically, some yuppies were former hippies or yippies, like Jerry Rubin, who gave up his crusade against “the establishment” to become a businessman.
### Section Summary
After decades of liberalism and social reform, Ronald Reagan changed the face of American politics by riding a groundswell of conservatism into the White House. Reagan’s superior rhetorical skills enabled him to gain widespread support for his plans for the nation. Implementing a series of economic policies dubbed “Reaganomics,” the president sought to stimulate the economy while shrinking the size of the federal government and providing relief for the nation’s wealthiest taxpayers. During his two terms in office, he cut spending on social programs, while increasing spending on defense. While Reagan was able to break the cycle of stagflation, his policies also triggered a recession, plunged the nation into a brief period of significant unemployment, and made a balanced budget impossible. In the end, Reagan’s policies diminished many Americans’ quality of life while enabling more affluent Americans—the “Yuppies” of the 1980s—to prosper.
### Review Questions
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# From Cold War to Culture Wars, 1980-2000
## Political and Cultural Fusions
Ronald Reagan’s victory in 1980 suggested to conservatives that the days of liberalism were over and the liberal establishment might be dismantled. Many looked forward to the discontinuation of policies like affirmative action. Conservative Christians sought to outlaw abortion and stop the movement for gay and lesbian rights. Republicans, and some moderate Democrats, demanded a return to “traditional” family values, a rhetorical ploy to suggest that male authority over women and children constituted a natural order that women’s rights and the New Left had subverted since the 1960s. As the conservative message regarding the evils of government permeated society, distrust of the federal government grew, inspiring some to form organizations and communities that sought complete freedom from government control.
### CREATING CONSERVATIVE POLICY
Ronald Reagan’s popularity and effectiveness as a leader drew from his reputation as a man who fought for what he believed in. He was a very articulate spokesperson for a variety of political ideas based on conservative principles and perspectives. Much of the intellectual meat of the Reagan Revolution came from conservative think tanks (policy or advocacy groups) that specifically sought to shape American political and social dialogues. The Heritage Foundation, one such group, soon became the intellectual arm of the conservative movement.
Launched in 1973 with a $250,000 contribution from Joseph Coors (of Coors Brewing Company) and support from a variety of corporations and conservative foundations, the Heritage Foundation sought to counteract what conservatives believed to be Richard Nixon’s acceptance of a liberal consensus on too many issues. In producing its policy position papers and political recommendations to conservative candidates and politicians, it helped contribute to a sanitization of U.S. history and a nostalgic glorification of what it deemed to be traditional values, seemingly threatened by the expansion of political and personal freedoms. The foundation had lent considerable support and encouragement to the conservative dialogues that helped carry Ronald Reagan into office in 1980. Just a year later, it produced a document entitled Mandate for Leadership that catalogued some two thousand specific recommendations on how to shrink the size and reach of the federal government and implement a more consistent conservative agenda. The newly elected Reagan administration looked favorably on the recommendations and recruited several of the paper’s authors to serve in the White House.
### CONSERVATIVE CHRISTIANS AND FAMILY VALUES
Among the strongest supporters of Ronald Reagan’s campaign for president were members of the Religious Right, including Christian groups like the Moral Majority, 61 percent of whom voted for him. By 1980, evangelical Christians had become an important political and social force in the United States (). Some thirteen hundred radio stations in the country were owned and operated by evangelicals. Christian television programs, such as Pat Robertson’s The 700 Club and Jim Bakker’s The PTL (Praise the Lord) Club, proved enormously popular and raised millions of dollars from viewer contributions. For some, evangelism was a business, but most conservative Christians were true believers who were convinced that premarital and extramarital sex, abortion, drug use, homosexuality, and “irreligious” forms of popular and high culture were responsible for a perceived decline in traditional family values that threatened American society.
Despite the support he received from Christian conservative and family values voters, Reagan was hardly an ideologue when it came to policy. Indeed, he was often quite careful in using hot button, family-value issues to his greatest political advantage. For example, as governor of California, one of the states that ratified the Equal Rights Amendment (ERA) in its first year, he positioned himself as a supporter of the amendment. When he launched his bid for the Republican nomination in 1976, however, he withdrew his support to gain the backing of more conservative members of his party. This move demonstrated both political savvy and foresight. At the time he withdrew his support, the Republican National Convention was still officially backing the amendment. However, in 1980, the party began to qualify its stance, which dovetailed with Reagan’s candidacy for the White House.
Reagan believed the Fourteenth Amendment to the Constitution was sufficient protection for women against discrimination. Once in office, he took a mostly neutral position, neither supporting nor working against the ERA. Nor did this middle position appear to hurt him at the polls; he attracted a significant number of votes from women in 1980, and in 1984, he polled 56 percent of the women’s vote compared to 44 percent for the Democratic ticket of Walter Mondale and Geraldine Ferraro, the first female candidate for vice president from a major party.
Reagan’s political calculations notwithstanding, his belief that traditional values were threatened by a modern wave of immoral popular culture was genuine. He recognized that nostalgia was a powerful force in politics, and he drew a picture for his audiences of the traditional good old days under attack by immorality and decline. “Those of us who are over thirty-five or so years of age grew up in a different America,” he explained in his farewell address. “We were taught, very directly, what it means to be an American. And we absorbed, almost in the air, a love of country and an appreciation of its institutions. . . . The movies celebrated democratic values and implicitly reinforced the idea that America was special.” But this America, he insisted, was being washed away. “I’m warning of an eradication of the American memory that could result, ultimately, in an erosion of the American spirit.”
Concern over a decline in the country’s moral values welled up on both sides of the political aisle. In 1985, anxiety over the messages of the music industry led to the founding of the Parents Music Resource Center (PMRC), a bipartisan group formed by the wives of prominent Washington politicians including Susan Baker, the wife of Reagan’s treasury secretary, James Baker, and Tipper Gore, the wife of then-senator Al Gore, a Democrat, who later became vice president under Bill Clinton. The goal of the PMRC was to limit the ability of children to listen to music with sexual or violent content. Its strategy was to get the recording industry to adopt a voluntary rating system for music and recordings, similar to the Motion Picture Association of America’s system for movies.
The organization also produced a list of particularly offensive recordings known as the “filthy fifteen.” By August 1985, nearly twenty record companies had agreed to put labels on their recordings indicating “explicit lyrics,” but the Senate began hearings on the issue in September (). While many parents and a number of witnesses advocated the labels, many in the music industry rejected them as censorship. Twisted Sister’s Dee Snider and folk musician John Denver both advised Congress against the restrictions. In the end, the recording industry suggested a voluntary generic label. Its effect on children’s exposure to raw language is uncertain, but musicians roundly mocked the effort.
### THE AIDS CRISIS
In the early 1980s, doctors noticed a disturbing trend: Young gay men in large cities, especially San Francisco and New York, were being diagnosed with, and eventually dying from, a rare cancer called Kaposi’s sarcoma. Because the disease was seen almost exclusively in gay males, it was quickly dubbed “gay cancer.” Doctors soon realized it often coincided with other symptoms, including a rare form of pneumonia, and they renamed it “Gay Related Immune Deficiency” (GRID), although people other than gay men, primarily intravenous drug users, were dying from the disease as well. The connection between gay men and GRID—later renamed human immunodeficiency virus/autoimmune deficiency syndrome, or HIV/AIDS—led straight people and mainstream news organizations to largely ignore the growing health crisis in the gay community, wrongly assuming they were safe from its effects. The federal government also overlooked the disease, and calls for more money to research and find the cure were ignored.
Even after it became apparent that straight people could contract the disease through blood transfusions and heterosexual intercourse, HIV/AIDS continued to be associated primarily with the gay community, especially by political and religious conservatives. Indeed, the Religious Right regarded it as a form of divine retribution meant to punish gay men for their “immoral” lifestyle. President Reagan, always politically careful, was reluctant to speak openly about the developing crisis even as thousands faced certain death from the disease.
With little help coming from the government, the gay community quickly began to organize its own response. In 1982, New York City men formed the Gay Men’s Health Crisis (GMHC), a volunteer organization that operated an information hotline, provided counseling and legal assistance, and raised money for people with HIV/AIDS. Larry Kramer, one of the original members, left in 1983 and formed his own organization, the AIDS Coalition to Unleash Power (ACT UP), in 1987. ACT UP took a more militant approach, holding demonstrations on Wall Street, outside the U.S. Food and Drug Administration (FDA), and inside the New York Stock Exchange to call attention and shame the government into action. One of the images adopted by the group, a pink triangle paired with the phrase “Silence = Death,” captured media attention and quickly became the symbol of the AIDS crisis ().
### THE WAR ON DRUGS AND THE ROAD TO MASS INCARCERATION
As Ronald Reagan took office in 1981, violent crime in the United States was reaching an all-time high. While there were different reasons for the spike, the most important one was demographics: The primary category of offenders, males between the ages of sixteen and thirty-six, reached an all-time peak as the baby-boomer generation came of age. But the phenomenon that most politicians honed in on as a cause for violent crime was the abuse of a new, cheap drug dealt illegally on city streets. Crack cocaine, a smokable type of cocaine popular with poorer addicts, was hitting the streets in the 1980s, frightening middle-class Americans. Reagan and other conservatives led a campaign to “get tough on crime” and promised the nation a “war on drugs.” Initiatives like the “Just Say No” campaign led by First Lady Nancy Reagan implied that drug addiction and drug-related crime reflected personal morality.
Nixon had first used the term in 1971, but in the 1980s the war on drugs took on an ominous dimension, as politicians scrambled over each other to enact harsher sentences for drug offenses so they could market themselves as tough on crime. Penalties for crack possession and use far exceeded penalties for similar amounts of cocaine, a more expensive drug more commonly used by White people. State after state switched from variable to mandatory minimum sentences that were exceedingly long and particularly harsh for street drug crimes. The federal government supported the trend with federal sentencing guidelines, removal of judges' discretion, and additional funds for local law enforcement agencies. Practices like civil forfeiture, in which law enforcement or municipalities could seize and share cash and property of suspected criminals even before they were convicted, provided a significant incentive to investigate drug crimes. The additional funding sources and high likelihood of successful prosecution drove police forces toward more aggressive and inequitable tactics. Black and Hispanic people were many times more likely than White people to be pulled over for routine traffic stops and searches. Local police forces dedicated far more resources to patrolling minority-inhabited neighborhoods, resulting in far more arrests and prosecutions of Black and Hispanic people. This practice of racial profiling would become a civil liberties flash point, but the results were devastating to significant portions of the population.
The law-and-order movement peaked in the 1990s, when California introduced a “three strikes” law that mandated life imprisonment without parole for any third felony conviction—even nonviolent ones. As a result, prisons became crowded, and states went deep into debt to build more. By the end of the century, the war began to die down as the public lost interest in the problem, the costs of the punishment binge became politically burdensome, and scholars and politicians began to advocate the decriminalization of drug use. By this time, however, hundreds of thousands of people had been incarcerated for drug offenses and the total number of prisoners in the nation had grown four-fold in the last quarter of the century. Particularly glaring were the racial inequities of the new age of mass incarceration, with African Americans being seven times more likely to be in prison (). In some states, such as New York, over 90 percent of people in prison were Black or Hispanic. Incarcerated people could neither generate income nor support their communities and families. In most states, convicted felons could not vote while in prison and even upon their release, which reduced the impact of minorities in legislation and representative bodies. And many companies and organizations avoided hiring people who had been previously convicted of felonies, resulting in a cycle of poverty and social stagnation that existed on stark racial lines.
Greater awareness around police practices and use of force developed with the increased availability of recording devices. In 1991, the country watched a citizen's video of Los Angeles police officers repeatedly beating an unarmed man, Rodney King, with their batons. Over a minute of footage showed dozens of strikes and kicks while King lay on the ground or attempted to rise. The officers were put on trial for assault and excessive force, but were ultimately acquitted. In the riots that followed the acquittal, 63 people were killed and and over two thousand injured, with over $1 billion in damage. President Bush said that, "it was hard to understand how the verdict could square with the video." Two of the officers were later convicted of federal charges for willfully using unreasonable force.
### Section Summary
The political conservatism of the 1980s and 1990s was matched by the social conservatism of the period. Conservative politicians wished to limit the size and curb the power of the federal government. Conservative think tanks flourished, the Christian Right defeated the ERA, and bipartisan efforts to add warning labels to explicit music lyrics were the subject of Congressional hearings. HIV/AIDS, which became chiefly and inaccurately associated with the gay community, grew to crisis proportions, as straight people, the medical community, and the federal government failed to act. In response, gay men organized advocacy groups to fight for research on HIV/AIDS. Meanwhile, the so-called war on drugs began a get-tough trend in law enforcement that mandated lengthy sentences for drug-related offenses and hugely increased the American prison population. Prosecutions and mass incarceration were perpetuated largely on racial lines; Black and Hispanic people and communities were severely impacted by inequitable legal pursuits and imprisonment.
### Review Questions
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# From Cold War to Culture Wars, 1980-2000
## A New World Order
In addition to reviving the economy and reducing the size of the federal government, Ronald Reagan also wished to restore American stature in the world. He entered the White House a “cold warrior” and referred to the Soviet Union in a 1983 speech as an “evil empire.” Dedicated to upholding even authoritarian governments in foreign countries to keep them safe from Soviet influence, he was also desperate to put to rest Vietnam Syndrome, the reluctance to use military force in foreign countries for fear of embarrassing defeat, which had influenced U.S. foreign policy since the mid-1970s.
### THE MIDDLE EAST AND CENTRAL AMERICA
Reagan’s desire to demonstrate U.S. readiness to use military force abroad sometimes had tragic consequences. In 1983, he sent soldiers to Lebanon as part of a multinational force trying to restore order following an Israeli invasion the year before. On October 23, more than two hundred troops were killed in a barracks bombing in Beirut carried out by Iranian-trained militants known as Hezbollah (). In February 1984, Reagan announced that, given intensified fighting, U.S. troops were being withdrawn.
Two days after the bombing in Beirut, Reagan and Secretary of State George P. Shultz authorized the invasion of Grenada, a small Caribbean island nation, in an attempt to oust a Communist military junta that had overthrown a moderate regime. Communist Cuba already had troops and technical aid workers stationed on the island and were willing to defend the new regime, but the United States swiftly took command of the situation, and the Cuban soldiers surrendered after two days.
Reagan’s intervention in Grenada was intended to send a message to Marxists in Central America. Meanwhile, however, decades of political repression and economic corruption by certain Latin American governments, sometimes generously supported by U.S. foreign aid, had sown deep seeds of revolutionary discontent. In El Salvador, a 1979 civil-military coup had put a military junta in power that was engaged in a civil war against left-leaning guerillas when Reagan took office. His administration supported the right-wing government, which used death squads to silence dissent.
Neighboring Nicaragua was also governed by a largely Marxist-inspired group, the Sandinistas. This organization, led by Daniel Ortega, had overthrown the brutal, right-wing dictatorship of Anastasio Somoza in 1979. Reagan, however, overlooked the legitimate complaints of the Sandinistas and believed that their rule opened the region to Cuban and Soviet influence. A year into his presidency, convinced it was folly to allow the expansion of Soviet and Communist influence in Latin America, he authorized the Central Intelligence Agency (CIA) to equip and train a group of anti-Sandinista Nicaraguans known as the Contras (contrarevolucionários or “counter-revolutionaries”) to oust Ortega.
Reagan’s desire to aid the Contras even after Congress ended its support led him, surprisingly, to Iran. In September 1980, Iraq had invaded neighboring Iran and, by 1982, had begun to gain the upper hand. The Iraqis needed weapons, and the Reagan administration, wishing to assist the enemy of its enemy, had agreed to provide Iraqi president Saddam Hussein with money, arms, and military intelligence. In 1983, however, the capture of Americans by Hezbollah forces in Lebanon changed the president’s plans. In 1985, he authorized the sale of anti-tank and anti-aircraft missiles to Iran in exchange for help retrieving three of the American hostages.
A year later, Reagan’s National Security Council aide, Lieutenant Colonel Oliver North, found a way to sell weapons to Iran and secretly use the proceeds to support the Nicaraguan Contras—in direct violation of a congressional ban on military aid to the anti-Communist guerillas in that Central American nation. Eventually the Senate became aware, and North and others were indicted on various charges, which were all dismissed, overturned on appeal, or granted presidential pardon. Reagan, known for delegating much authority to subordinates and unable to “remember” crucial facts and meetings, escaped the scandal with nothing more than criticism for his lax oversight. The nation was divided over the extent to which the president could go to “protect national interests,” and the limits of Congress’s constitutional authority to oversee the activities of the executive branch have yet to be resolved.
### THE COLD WAR WAXES AND WANES
While trying to shrink the federal budget and the size of government sphere at home, Reagan led an unprecedented military buildup in which money flowed to the Pentagon to pay for expensive new forms of weaponry. The press drew attention to the inefficiency of the nation’s military industrial complex, offering as examples expense bills that included $640 toilet seats and $7,400 coffee machines. One of the most controversial aspects of Reagan’s plan was the Strategic Defense Initiative (SDI), which he proposed in 1983. SDI, or “Star Wars,” called for the development of a defensive shield to protect the United States from a Soviet missile strike. Scientists argued that much of the needed technology had not yet been developed and might never be. Others contended that the plan would violate existing treaties with the Soviet Union and worried about the Soviet response. The system was never built, and the plan, estimated to have cost some $7.5 billion, was finally abandoned.
After his reelection in 1984, Reagan began to moderate his position toward the Soviets. Mikhail Gorbachev became the General Secretary of the Soviet Communist Party and was willing to meet with the president. Reagan found he was able to work with the Soviet leader once Gorbachev distanced himself from the traditional communist policies. The new and comparatively young Soviet premier did not want to commit additional funds for another arms race, especially since the war in Afghanistan against mujahedeen—Islamic guerilla fighters—had depleted the Soviet Union’s resources severely since its invasion of the central Asian nation in 1979. Gorbachev recognized that economic despair at home could easily result in larger political upheavals like those in neighboring Poland, where the Solidarity movement had taken hold. He withdrew troops from Afghanistan, introduced political reforms and new civil liberties at home—known as perestroika and glasnost—and proposed arms reduction talks with the United States. In 1985, Gorbachev and Reagan met in Geneva to reduce armaments and shrink their respective military budgets. The following year, meeting in Reykjavík, Iceland, they surprised the world by announcing that they would try to eliminate nuclear weapons by 1996. In 1987, they agreed to eliminate a whole category of nuclear weapons when they signed the Intermediate-Range Nuclear Forces (INF) Treaty at the White House (). This laid the foundation for future agreements limiting nuclear weapons.
### AFRICAN AMERICAN VISIBILITY AND LEADERSHIP
While desegregated education had been established by the 1954 Brown v. Board of Education decision, the government had few mechanisms to enforce desegregation until the 1964 Civil Rights Act. Only then could minorities and other underrepresented people begin to expect more equal treatment in employment and access to public resources. The outcomes were notable, but the challenges remained.
The 1970 census, conducted only six years after the passing of the Civil Rights Act, found that only 38 percent of Black men had a high school diploma, with only 13 percent attending college and 6 percent earning a bachelor's degree. By 1980, however, educational attainment had skyrocketed: 64 percent of Black men achieved a high school diploma, with 28 percent attending college. Historically, Black women had a greater level of educational attainment than Black men, and they benefited from the gains as well. Better education, coupled with protections against employment discrimination, began to offer Black people more economic opportunities.
Black writers, artists, actors, and other figures had a significant impact on 1980s culture and consciousness, coinciding with the frequency of their presence on mainstream television. In 1982, Bryant Gumbel became the first Black anchor on network television. Soon after, the Miss America pageant crowned Vanessa Williams as its first Black winner. Later in the decade, Oprah Winfrey began a talk show known for addressing socially charged and difficult topics while it skyrocketed to unparalleled viewership. And after an initial period of avoiding Black artists, MTV would soon heavily feature R&B and Hip-Hop acts, leading to increased admiration and emulation among youth of all backgrounds.
Alice Walker's The Color Purple received widespread critical acclaim, becoming the first novel by a Black woman to win the Pulitzer Prize. The novel depicts a woman who endures sexual, physical, and emotional abuse at the hands of her father and other men. After suffering loss and separation, she draws strength from other powerful women, and together they triumph over their trauma. The novel brought forth the stark realities facing women; it became a cultural touchstone and a staple of literature curricula. The Color Purple, and especially its movie adaptation, also sparked controversy among some prominent figures, including director Spike Lee and talk show host Tony Brown, who felt that the narrative painted a negative picture of Black men.
Increased visibility could not overcome the challenges facing Black people in the 1980s. While the Reagan tax cuts offered financial gains for the wealthy, the decade saw an alarming rise in economic inequality—the disparity between income among different groups. The nation's overall employment rose, but the manufacturing sector faced steady declines. Cities in Ohio, Michigan, Western New York, Pennsylvania, and Indiana lost over half of their manufacturing jobs. Factory after factory closed, and companies from the automobile, steel, mining, and electronics industries began to shutter. The Manufacturing Belt (or Factory Belt), which ran through the Great Lakes Region, became degraded by poverty and urban decay to the point that it was renamed the Rust Belt. The unemployment rate was almost twice as high for Black people as it was for White people.
Advocates seeking to address these disparities gained greater influence. The most prominent among these was Jesse Jackson, a widely known civil rights figure who had both a domestic and international impact. As the leader of the People United to Serve Humanity (PUSH), he'd led boycotts to drive more employment equality, and had successfully negotiated the release of American hostages in Syria and Cuba. His 1984 run for President was the second national campaign by an African American after Shirley Chisholm's in 1972. Jackson's third-place showing in the Democratic primaries was a better result than expected, and gave him greater credibility leading up to his more successful candidacy in 1988.
Jackson's 1988 campaign again centered on workers and refocusing America's priorities. He led a protest at a Wisconsin auto plant slated for closing, earning him the endorsement of the regional autoworkers union. His platform included plans to eliminate the mandatory minimum sentences responsible for mass incarceration, as well as guarantees of universal health care and free community college. While considered exceedingly liberal, these positions earned him strong placement in the primary process, building on the support of a "Rainbow Coalition" of minorities and the working class as well as progressives. He would eventually finish second to the eventual nominee, Michael Dukakis, and spent the waning days of his campaign ensuring that African Americans' issues remained a priority within the party.
While a lesser known candidate, Lenora Fulani achieved an important new milestone for Black women with her own Presidential campaign. As part of one of several minor parties in the election, Fulani became the first woman and the first Black person to gain Presidential ballot access in all 50 states. She would get the most votes of any woman until Jill Stein in 2012.
### “NO NEW TAXES”
Confident they could win back the White House, Democrats mounted a campaign focused on more effective and competent government under the leadership of Massachusetts governor Michael Dukakis. When George H. W. Bush, Reagan’s vice president and Republican nominee, found himself down in the polls, political advisor Lee Atwater launched an aggressively negative media campaign, accusing Dukakis of being soft on crime and connecting his liberal policies to a brutal murder in Massachusetts. More importantly, Bush adopted a largely Reaganesque style on matters of economic policy, promising to shrink government and keep taxes low. These tactics were successful, and the Republican Party retained the White House.
Although he promised to carry on Reagan’s economic legacy, the problems Bush inherited made it difficult to do so. Reagan’s policies of cutting taxes and increasing defense spending had exploded the federal budget deficit, making it three times larger in 1989 than when Reagan took office in 1980. Bush was further constrained by the emphatic pledge he had made at the 1988 Republican Convention—“read my lips: no new taxes”—and found himself in the difficult position of trying to balance the budget and reduce the deficit without breaking his promise. However, he also faced a Congress controlled by the Democrats, who wanted to raise taxes on the rich, while Republicans thought the government should drastically cut domestic spending. In October, after a brief government shutdown when Bush vetoed the budget Congress delivered, he and Congress reached a compromise with the Omnibus Budget Reconciliation Act of 1990. The budget included measures to reduce the deficit by both cutting government expenditures and raising taxes, effectively reneging on the “no new taxes” pledge. These economic constraints are one reason why Bush supported a limited domestic agenda of education reform and antidrug efforts, relying on private volunteers and community organizations, which he referred to as “a thousand points of light,” to address most social problems.
When it came to foreign affairs, Bush’s attitude towards the Soviet Union differed little from Reagan’s. Bush sought to ease tensions with America’s rival superpower and stressed the need for peace and cooperation. The desire to avoid angering the Soviets led him to adopt a hands-off approach when, at the beginning of his term, a series of pro-democracy demonstrations broke out across the Communist Eastern Bloc.
In November 1989, the world—including foreign policy experts and espionage agencies from both sides of the Iron Curtain—watched in surprise as peaceful protesters in East Germany marched through checkpoints at the Berlin Wall. Within hours, people from both East and West Berlin flooded the checkpoints and began tearing down large chunks of the wall. Months of earlier demonstrations in East Germany had called on the government to allow citizens to leave the country. These demonstrations were one manifestation of a larger movement sweeping across East Germany, Poland, Hungary, Czechoslovakia, Bulgaria, and Romania, which swiftly led to revolutions, most of them peaceful, resulting in the collapse of Communist governments in Central and Eastern Europe.
In Budapest in 1956 and in Prague in 1968, the Soviet Union had restored order through a large show of force. That this didn’t happen in 1989 was an indication to all that the Soviet Union was itself collapsing. Bush’s refusal to gloat or declare victory helped him maintain the relationship with Gorbachev that Reagan had established. In July 1991, Gorbachev and Bush signed the Strategic Arms Reduction Treaty, or START, which committed their countries to reducing their nuclear arsenals by 25 percent. A month later, attempting to stop the changes begun by Gorbachev’s reforms, Communist Party hardliners tried to remove him from power. Protests arose throughout the Soviet Union, and by December 1991, the nation had collapsed. In January 1992, twelve former Soviet republics formed the Commonwealth of Independent States to coordinate trade and security measures. The Cold War was over.
### AMERICAN GLOBAL POWER IN THE WAKE OF THE COLD WAR
The dust had barely settled on the crumbling Berlin Wall when the Bush administration announced a bold military intervention in Panama in December 1989. Claiming to act on behalf of human rights, U.S. troops deposed the unpopular dictator and drug smuggler Manuel Noriega swiftly, but former CIA connections between President Bush and Noriega, as well as U.S. interests in maintaining control of the Canal Zone, prompted the United Nations and world public opinion to denounce the invasion as a power grab.
As the Soviet Union was ceasing to be a threat, the Middle East became a source of increased concern. In the wake of its eight-year war with Iran from 1980 to 1988, Iraq had accumulated a significant amount of foreign debt. At the same time, other Arab states had increased their oil production, forcing oil prices down and further hurting Iraq’s economy. Iraq’s leader, Saddam Hussein, approached these oil-producing states for assistance, particularly Saudi Arabia and neighboring Kuwait, which Iraq felt directly benefited from its war with Iran. When talks with these countries broke down, and Iraq found itself politically and economically isolated, Hussein ordered the invasion of oil-rich Kuwait in August 1990. Bush faced his first full-scale international crisis.
In response to the invasion, Bush and his foreign policy team forged an unprecedented international coalition of thirty-four countries, including many members of NATO (North Atlantic Treaty Organization) and the Middle Eastern countries of Saudi Arabia, Syria, and Egypt, to oppose Iraqi aggression. Bush hoped that this coalition would herald the beginning of a “new world order” in which the nations of the world would work together to deter belligerence. A deadline was set for Iraq to withdraw from Kuwait by January 15, or face serious consequences. Wary of not having sufficient domestic support for combat, Bush first deployed troops to the area to build up forces in the region and defend Saudi Arabia via Operation Desert Shield (). On January 14, Bush succeeded in getting resolutions from Congress authorizing the use of military force against Iraq, and the U.S. then orchestrated an effective air campaign, followed by Operation Desert Storm, a one-hundred-hour land war involving over 500,000 U.S. troops and another 200,000 from twenty-seven other countries, which expelled Iraqi forces from Kuwait by the end of February.
Some controversy arose among Bush’s advisors regarding whether to end the war without removing Saddam Hussein from power, but General Colin Powell, the head of the Joint Chiefs of Staff, argued that to continue to attack a defeated army would be “un-American.” Bush agreed and troops began moving out of the area in March 1991. Although Hussein was not removed from power, the war nevertheless suggested that the United States no longer suffered from “Vietnam Syndrome” and would deploy massive military resources if and when it thought necessary. In April 1991, United Nations (UN) Resolution 687 set the terms of the peace, with long-term implications. Its concluding paragraph authorizing the UN to take such steps as necessary to maintain the peace was later taken as the legal justification for the further use of force, as in 1996 and 1998, when Iraq was again bombed. It was also referenced in the lead-up to the second invasion of Iraq in 2003, when it appeared that Iraq was refusing to comply with other UN resolutions.
### A CHANGING DOMESTIC LANDSCAPE
By nearly every measure, Operation Desert Storm was a resounding success. Through deft diplomatic efforts on the international stage, Bush had ensured that many around the world saw the action as legitimate. By making the goals of the military action both clear and limited, he also reassured an American public still skeptical of foreign entanglements. With the Soviet Union vanishing from the world stage, and the United States demonstrating the extent of its diplomatic influence and military potency with President Bush at the helm, his reelection seemed all but inevitable. Indeed, in March 1991, the president had an approval rating of 89 percent.
Despite Bush’s successes internationally, the domestic situation at home was far more complicated. Unlike Reagan, Bush was not a natural culture warrior. Rather, he was a moderate, Connecticut-born Episcopalian, a pragmatic politician, and a life-long civil servant. He was not adept at catering to post-Reagan conservatives as his predecessor had been. By the same token, he appeared incapable of capitalizing on his history of moderation and pragmatism regarding women’s rights and access to abortion. Together with a Democratic Senate, Bush broke new ground in civil rights with his support of the Americans with Disabilities Act, a far-reaching law that prohibited discrimination based on disability in public accommodations and by employers.
President Bush’s weaknesses as a culture warrior were on full display during the controversy that erupted following his nomination of a new Supreme Court judge. In 1991, Justice Thurgood Marshall, the first African American ever to sit on the Supreme Court, opted to retire, thus opening a position on the court. Thinking he was doing the prudent thing by appealing to multiple interests, Bush nominated Clarence Thomas, another African American but also a strong social conservative. The decision to nominate Thomas, however, proved to be anything but prudent. During Thomas’ confirmation hearings before the Senate Judiciary Committee, Anita Hill, a lawyer who had worked for Thomas when he was chairman of the Equal Employment Opportunity Commission (EEOC), came forward with allegations that he had sexually harassed her when he was her supervisor. Thomas denied the accusations and referred to the televised hearings as a "high tech lynching." He survived the controversy and was appointed to the Supreme Court by a narrow Senate vote of fifty-two to forty-eight. Hill, also African American, noted later in frustration: “I had a gender, he had a race.” In the aftermath, however, sexual harassment of women in the workplace gained public attention, and harassment complaints made to the EEOC increased 50 percent by the fall of 1992. The controversy also reflected poorly on President Bush and may have hurt him with female voters in 1992.
### Section Summary
While Ronald Reagan worked to restrict the influence of the federal government in people’s lives, he simultaneously pursued interventionist policies abroad as part of a global Cold War strategy. Eager to cure the United States of “Vietnam Syndrome,” he increased the American stockpile of weapons and aided anti-Communist groups in the Caribbean and Central America. The Reagan administration’s secret sales of arms to Iran proved disastrous, however, and resulted in indictments for administration officials. With the end of the Cold War, attention shifted to escalating tensions in the Middle East, where an international coalition assembled by George H. W. Bush drove invading Iraqi forces from Kuwait. As Bush discovered in the last years of his presidency, even this almost-flawless exercise in international diplomatic and military power was not enough to calm a changing cultural and political climate at home.
### Review Questions
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# From Cold War to Culture Wars, 1980-2000
## Bill Clinton and the New Economy
By 1992, many had come to doubt that President George H. W. Bush could solve America’s problems. He had alienated conservative Republicans by breaking his pledge not to raise taxes, and some faulted him for failing to remove Saddam Hussein from power during Operation Desert Storm. Furthermore, despite living much of his adult life in Texas, he could not overcome the stereotypes associated with his privileged New England and Ivy League background, which hurt him among working-class Reagan Democrats.
### THE ROAD TO THE WHITE HOUSE
The contrast between George H. W. Bush and William Jefferson Clinton could not have been greater. Bill Clinton was a baby boomer born in 1946 in Hope, Arkansas. His biological father died in a car wreck three months before he was born. When he was a boy, his mother married Roger Clinton, an alcoholic who abused his family. However, despite a troubled home life, Clinton was an excellent student. He took an interest in politics from an early age. On a high school trip to Washington, DC, he met his political idol, President John F. Kennedy. As a student at Georgetown University, he supported both the civil rights and antiwar movements and ran for student council president ().
In 1968, Clinton received a prestigious Rhodes scholarship to Oxford University. From Oxford he moved on to Yale, where he earned his law degree in 1973. He returned to Arkansas and became a professor at the University of Arkansas’s law school. The following year, he tried his hand at state politics, running for Congress, and was narrowly defeated. In 1977, he became attorney general of Arkansas and was elected governor in 1978. Losing the office to his Republican opponent in 1980, he retook the governor’s mansion in 1982 and remained governor of Arkansas until 1992, when he announced his candidacy for president.
During his campaign, Bill Clinton described himself as a New Democrat, a member of a faction of the Democratic Party that, like the Republicans, favored free trade and deregulation. He tried to appeal to the middle class by promising higher taxes on the rich and reform of the welfare system. Although Clinton garnered only 43 percent of the popular vote, he easily won in the Electoral College with 370 votes to President Bush’s 188. Texas billionaire H. Ross Perot won 19 percent of the popular vote, the best showing by any third-party candidate since 1912. The Democrats took control of both houses of Congress.
### “IT’S THE ECONOMY, STUPID”
Clinton took office towards the end of a recession. His administration’s plans for fixing the economy included limiting spending and cutting the budget to reduce the nation’s $60 billion deficit, keeping interest rates low to encourage private investment, and eliminating protectionist tariffs. Clinton also hoped to improve employment opportunities by allocating more money for education. In his first term, he expanded the Earned Income Tax Credit, which lowered the tax obligations of working families who were just above the poverty line. Addressing the budget deficit, the Democrats in Congress passed the Omnibus Budget Reconciliation Act of 1993 without a single Republican vote. The act raised taxes for the top 1.2 percent of the American people, lowered them for fifteen million low-income families, and offered tax breaks to 90 percent of small businesses.
Clinton also strongly supported ratification of the North American Free Trade Agreement (NAFTA), a treaty that eliminated tariffs and trade restrictions among the United States, Canada, and Mexico. The treaty had been negotiated by the Bush administration, and the leaders of all three nations had signed it in December 1992. However, because of strong opposition from American labor unions and some in Congress who feared the loss of jobs to Mexico, the treaty had not been ratified by the time Clinton took office. To allay the concerns of unions, he added an agreement to protect workers and also one to protect the environment. Congress ratified NAFTA late in 1993. The result was the creation of the world’s largest common market in terms of population, including some 425 million people.
During Clinton’s administration, the nation began to experience the longest period of economic expansion in its history, almost ten consecutive years. Year after year, job growth increased and the deficit shrank. Increased tax revenue and budget cuts turned the annual national budget deficit from close to $290 billion in 1992 to a record budget surplus of over $230 billion in 2000. Reduced government borrowing freed up capital for private-sector use, and lower interest rates in turn fueled more growth. During the Clinton years, more people owned homes than ever before in the country’s history (67.7 percent). Inflation dipped to 2.3 percent and the unemployment rate declined, reaching a thirty-year low of 3.9 percent in 2000.
Much of the prosperity of the 1990s was related to technological change and the advent of new information systems. In 1994, the Clinton administration became the first to launch an official White House website and join the revolution of the electronically mediated world. By the 1990s, a new world of instantaneous global exposure was at the fingertips of billions worldwide.
### DOMESTIC ISSUES
In addition to shifting the Democratic Party to the moderate center on economic issues, Clinton tried to break new ground on a number of domestic issues and make good on traditional Democratic commitments to the disadvantaged, minority groups, and women. At the same time, he faced the challenge of domestic terrorism when a federal building in Oklahoma City was bombed, killing 168 people and injuring hundreds more.
### Healthcare Reform
An important and popular part of Clinton’s domestic agenda was healthcare reform that would make universal healthcare a reality. When the plan was announced in September of the president’s first year in office, pollsters and commentators both assumed it would sail through. Many were unhappy with the way the system worked in the United States, where the cost of health insurance seemed increasingly unaffordable for the middle class. Clinton appointed his wife, Hillary Clinton, a Yale Law School graduate and accomplished attorney, to head his Task Force on National Health Care Reform in 1993. The 1,342-page Health Security Act presented to Congress that year sought to offer universal coverage (). All Americans were to be covered by a healthcare plan that could not reject them based on pre-existing medical conditions. Employers would be required to provide healthcare for their employees. Limits would be placed on the amount that people would have to pay for services; the poor would not have to pay at all.
The outlook for the plan looked good in 1993; it had the support of a number of institutions like the American Medical Association and the Health Insurance Association of America. But in relatively short order, the political winds changed. As budget battles distracted the administration and the midterm elections of 1994 approached, Republicans began to recognize the strategic benefits of opposing reform. Soon they were mounting fierce opposition to the bill. Moderate conservatives dubbed the reform proposals “Hillarycare” and argued that the bill was an unwarranted expansion of the powers of the federal government that would interfere with people’s ability to choose the healthcare provider they wanted. Those further to the right argued that healthcare reform was part of a larger and nefarious plot to control the public.
To rally Republican opposition to Clinton and the Democrats, Newt Gingrich and Richard “Dick” Armey, two of the leaders of the Republican minority in the House of Representatives, prepared a document entitled Contract with America, signed by all but two of the Republican representatives. It listed eight specific legislative reforms or initiatives the Republicans would enact if they gained a majority in Congress in the 1994 midterm elections.
Lacking support on both sides, the healthcare bill was never passed and died in Congress. The reform effort finally ended in September 1994. Dislike of the proposed healthcare plan on the part of conservatives and the bold strategy laid out in the Contract with America enabled the Republican Party to win seven Senate seats and fifty-two House seats in the November elections. The Republicans then used their power to push for conservative reforms. One such piece of legislation was the Personal Responsibility and Work Opportunity Reconciliation Act, signed into law in August 1996. The act set time limits on welfare benefits and required most recipients to begin working within two years of receiving assistance.
### Don’t Ask, Don’t Tell
Although Clinton had campaigned as an economically conservative New Democrat, he was thought to be socially liberal and, just days after his victory in the 1992 election, he promised to end the fifty-year ban on gays and lesbians serving in the military. However, in January 1993, after taking the oath of office, Clinton amended his promise in order to appease conservatives. Instead of lifting the longstanding ban, the armed forces would adopt a policy of “don’t ask, don’t tell.” Those on active duty would not be asked their sexual orientation and, if they were gay, they were not to discuss their sexuality openly or they would be dismissed from military service. This compromise satisfied neither conservatives nor the LGBTQ community, which argued that LGBTQ people should be able to live without fear of retribution because of their sexuality.
Clinton again proved himself willing to appease political conservatives when he signed into law the Defense of Marriage Act (DOMA) in September 1996, after both houses of Congress had passed it with such wide margins that a presidential veto could easily be overridden. DOMA defined marriage as a union between two people of the opposite sex, and denied federal benefits to same-sex couples. It also allowed states to refuse to recognize same-sex marriages granted by other states. When Clinton signed the bill, he was personally opposed to same-sex marriage. Nevertheless, he disliked DOMA and later called for its repeal. He also later changed his position on same-sex marriage. On other social issues, however, Clinton was more liberal. He appointed openly gay and lesbian men and women to important positions in government and denounced discrimination against people with AIDS. He supported the idea of the ERA and believed that women should receive pay equal to that of men doing the same work. He opposed the use of racial quotas in employment, but he declared affirmative action programs to be necessary.
Seeking to wrest the tough-on-crime reputation from Republicans, Clinton and Democratic leaders developed the largest Federal crime law to ever be enacted. While racially disparate policing and incarceration was already well established through efforts related to the War on Drugs, the 1994 Violent Crime Control and Law Enforcement Act added new penalties, funding, and incentives for aggressive law enforcement. The law helped states and communities expand police forces and build more prisons. Provisions to scale back parole also meant that people would remain incarcerated for longer periods of time regardless of behavior. The law also expanded the number of crimes punishable by death, enacted a sweeping assault weapons ban, and established the Violence Against Women Act. The 1994 law would have significant impacts on racial and ethnic minorities, continuing the pattern of inequitable mass incarceration and driving racially motivated policing. Based on its devastating impacts on Black and Hispanic people, the law would later have significant political consequences for Democrats who supported it.
As a result of his economic successes and his moderate social policies, Clinton defeated Senator Robert Dole in the 1996 presidential election. With 49 percent of the popular vote and 379 electoral votes, he became the first Democrat to win reelection to the presidency since Franklin Roosevelt. Clinton’s victory was partly due to a significant gender gap between the parties, with women tending to favor Democratic candidates. In 1992, Clinton won 45 percent of women’s votes compared to Bush’s 38 percent, and in 1996, he received 54 percent of women’s votes while Dole won 38 percent.
### Domestic Terrorism
The fears of those who saw government as little more than a necessary evil appeared to be confirmed in the spring of 1993, when federal and state law enforcement authorities laid siege to the compound of a religious sect called the Branch Davidians near Waco, Texas. The group, which believed the end of world was approaching, was suspected of weapons violations and resisted search-and-arrest warrants with deadly force. A standoff developed that lasted nearly two months and was captured on television each day. A final assault on the compound was made on April 19, and seventy-six men, women, and children died in a fire probably set by members of the sect. Many others committed suicide or were killed by fellow sect members.
During the siege, many antigovernment and militia types came to satisfy their curiosity or show support for those inside. One was Timothy McVeigh, a former U.S. Army infantry soldier. McVeigh had served in Operation Desert Storm in Iraq, earning a bronze star, but he became disillusioned with the military and the government when he was deemed psychologically unfit for the Army Special Forces. He was convinced that the Branch Davidians were victims of government terrorism, and he and his coconspirator, Terry Nichols, determined to avenge them.
Two years later, on the anniversary of the day that the Waco compound burned to the ground, McVeigh parked a rented truck full of explosives in front of the Alfred P. Murrah Federal Building in Oklahoma City and blew it up (). More than 600 people were injured in the attack and 168 died, including nineteen children at the daycare center inside. McVeigh hoped that his actions would spark a revolution against government control. He and Nichols were both arrested and tried, and McVeigh was executed on June 11, 2001, for the worst act of terrorism committed on American soil. Just a few months later, the terrorist attacks of September 11, 2001 broke that dark record.
### CLINTON AND AMERICAN HEGEMONY
For decades, the contours of the Cold War had largely determined U.S. action abroad. Strategists saw each coup, revolution, and civil war as part of the larger struggle between the United States and the Soviet Union. But with the Soviet Union vanquished, the United States was suddenly free of this paradigm, and President Clinton could see international crises in the Middle East, the Balkans, and Africa on their own terms and deal with them accordingly. He envisioned a post-Cold War role in which the United States used its overwhelming military superiority and influence as global policing tools to preserve the peace. This foreign policy strategy had both success and failure.
One notable success was a level of peace in the Middle East. In September 1993, at the White House, Yitzhak Rabin, prime minister of Israel, and Yasser Arafat, chairman of the Palestine Liberation Organization, signed the Oslo Accords, granting some self-rule to Palestinians living in the Israeli-occupied territories of the Gaza Strip and the West Bank (). A year later, the Clinton administration helped facilitate the second settlement and normalization of relations between Israel and Jordan.
As a small measure of stability was brought to the Middle East, violence erupted in the Balkans. The Communist country of Yugoslavia consisted of six provinces: Serbia, Croatia, Bosnia and Herzegovina, Slovenia, Montenegro, and Macedonia. Each was occupied by a number of ethnic groups, some of which shared a history of hostile relations. In May 1980, the leader of Yugoslavia, Josip Broz Tito, died. Without him to hold the country together, ethnic tensions increased, and this, along with the breakdown of Communism elsewhere in Europe, led to the breakup of Yugoslavia. In 1991, Croatia, Slovenia, and Macedonia declared their independence. In 1992, Bosnia and Herzegovina did as well. Only Serbia and Montenegro remained united as the Serbian-dominated Federal Republic of Yugoslavia.
Almost immediately, ethnic tensions within Bosnia and Herzegovina escalated into war when Yugoslavian Serbs aided Bosnian Serbs who did not wish to live in an independent Bosnia and Herzegovina. These Bosnian Serbs proclaimed the existence of autonomous Serbian regions within the country and attacked Bosnian Muslims and Croats. During the conflict, the Serbs engaged in genocide, described by some as “ethnic cleansing.” The brutal conflict also gave rise to the systematic rape of “enemy” women—generally Muslim women exploited by Serbian military or paramilitary forces. The International Criminal Tribunal of Yugoslavia estimated that between twelve thousand and fifty thousand women were raped during the war.
NATO eventually intervened in 1995, and Clinton agreed to U.S. participation in airstrikes against Bosnian Serbs. That year, the Dayton Accords peace settlement was signed in Dayton, Ohio. Four years later, the United States, acting with other NATO members, launched an air campaign against Serbian-dominated Yugoslavia to stop it from attacking ethnic Albanians in Kosovo. Although these attacks were not sanctioned by the UN and were criticized by Russia and China, Yugoslavia withdrew its forces from Kosovo in June 1999.
The use of force did not always bring positive results. For example, back in December 1992, George H. W. Bush had sent a contingent of U.S. soldiers to Somalia, initially to protect and distribute relief supplies to civilians as part of a UN mission. Without an effective Somali government, however, the warlords who controlled different regions often stole food, and their forces endangered the lives of UN workers. In 1993, the Clinton administration sent soldiers to capture one of the warlords, Mohammed Farah Aidid, in the city of Mogadishu. The resulting battle proved disastrous. A Black Hawk helicopter was shot down, and U.S. Army Rangers and members of Delta Force spent hours battling their way through the streets; eighty-four soldiers were wounded and nineteen died. The United States withdrew, leaving Somalia to struggle with its own anarchy.
The sting of the Somalia failure probably contributed to Clinton’s reluctance to send U.S. forces to end the 1994 genocide in Rwanda. In the days of brutal colonial rule, Belgian administrators had given control to Tutsi tribal chiefs, although Hutus constituted a majority of the population. Resentment over ethnic privileges, and the discrimination that began then and continued after independence in 1962, erupted into civil war in 1990. The Hutu majority began to slaughter the Tutsi minority and their Hutu supporters. In 1998, while visiting Rwanda, Clinton apologized for having done nothing to save the lives of the 800,000 massacred in one hundred days of genocidal slaughter.
### IMPEACHMENT
Public attention was diverted from Clinton’s foreign policing actions by a series of scandals that marked the last few years of his presidency. From the moment he entered national politics, his opponents had attempted to tie Clinton and his First Lady to a number of loosely defined improprieties, even accusing him of murdering his childhood friend and Deputy White House Counsel Vince Foster. One accusation the Clintons could not shake was of possible improper involvement in a failed real estate venture associated with the Whitewater Development Corporation in Arkansas in the 1970s and 1980s. Kenneth Starr, a former federal appeals court judge, was appointed to investigate the matter in August 1994.
While Starr was never able to prove any wrongdoing, he soon turned up other allegations and his investigative authority was expanded. In May 1994, Paula Jones, a former Arkansas state employee, filed a sexual harassment lawsuit against Bill Clinton. Starr’s office began to investigate this case as well. When a federal court dismissed Jones’s suit in 1998, her lawyers promptly appealed the decision and submitted a list of other alleged victims of Clinton’s harassment. That list included the name of Monica Lewinsky, a young White House intern. Both Lewinsky and Clinton denied under oath that they had had a sexual relationship. The evidence, however, indicated otherwise, and Starr began to investigate the possibility that Clinton had committed perjury. Again, Clinton denied any relationship and even went on national television to assure the American people that he had never had sexual relations with Lewinsky.
However, after receiving a promise of immunity, Lewinsky turned over to Starr evidence of her affair with Clinton, and the president admitted he had indeed had inappropriate relations with her. He nevertheless denied that he had lied under oath. In September, Starr reported to the House of Representatives that he believed Clinton had committed perjury. Voting along partisan lines, the Republican-dominated House of Representatives sent articles of impeachment to the Senate, charging Clinton with lying under oath and obstructing justice. In February 1998, the Senate voted forty-five to fifty-five on the perjury charge and fifty-fifty on obstruction of justice (). Although acquitted, Clinton did become the first president to be found in contempt of court. Nevertheless, although he lost his law license, he remained a popular president and left office at the end of his second term with an approval rating of 66 percent, the highest of any U.S. president.
### THE ELECTION OF 2000
Despite Clinton’s high approval rating, his vice president and the 2000 Democratic nominee for president, Al Gore, was eager to distance himself from scandal. Unfortunately, he also alienated Clinton loyalists and lost some of the benefit of Clinton’s genuine popularity. Gore’s desire to emphasize his concern for morality led him to select Connecticut senator Joseph I. Lieberman as his running mate. Lieberman had been quick to denounce Clinton’s relationship with Monica Lewinsky. Consumer advocate Ralph Nader ran as the candidate of the Green Party, a party devoted to environmental issues and grassroots activism, and Democrats feared that he would attract votes that Gore might otherwise win.
On the Republican side, where strategists promised to “restore honor and dignity” to the White House, voters were divided between George W. Bush, governor of Texas and eldest son of former president Bush, and John McCain, an Arizona senator and Vietnam War veteran. Bush had the robust support of both the Christian Right and the Republican leadership. His campaign amassed large donations that it used to defeat McCain, himself an outspoken critic of the influence of money in politics. The nomination secured, Bush selected Dick Cheney, part of the Nixon and Ford administrations and secretary of defense under George H. W. Bush, as his running mate.
One hundred million votes were cast in the 2000 election, and Gore topped Bush in the popular vote by 540,000 ballots, or 0.5 percent. The race was so close that news reports declared each candidate the winner at various times during the evening. It all came down to Florida, where early returns called the election in Bush’s favor by a mere 527 of 5,825,000 votes. Whoever won Florida would get the state’s twenty-five electoral votes and secure the presidency ().
Because there seemed to be irregularities in four counties traditionally dominated by Democrats, especially in largely African American precincts, Gore called for a recount of the ballots by hand. Florida’s secretary of state, Katherine Harris, set a deadline for the new vote tallies to be submitted, a deadline the counties could not meet. When the Democrats requested an extension, the Florida Supreme Court granted it, but Harris refused to accept the new tallies unless the counties could explain why they had not met the original deadline. When the explanations were submitted, they were rejected. Gore then asked the Florida Supreme Court for an injunction that would prevent Harris from declaring a winner until the recount was finished. On November 26, Harris declared Bush the winner in Florida. Gore protested that not all votes had been recounted by hand. When the Florida Supreme Court ordered the recount to continue, the Republicans appealed to the U.S. Supreme Court, which decided 5–4 to stop the recount. Bush received Florida’s electoral votes and, with a total of 271 votes in the Electoral College to Gore’s 266, became the forty-third president of the United States.
### Section Summary
Bill Clinton’s presidency and efforts at remaking the Democratic Party reflect the long-term effects of the Reagan Revolution that preceded him. Reagan benefited from a resurgent conservatism that moved the American political spectrum several degrees to the right. Clinton managed to remake the Democratic Party in ways that effectively institutionalized some of the major tenets of the so-called Reagan Revolution. A “New Democrat,” he moved the party significantly to the moderate center and supported the Republican call for law and order, and welfare reform—all while maintaining traditional Democratic commitments to minorities, women, and the disadvantaged, and using the government to stimulate economic growth. Nevertheless, Clinton’s legacy was undermined by the shift in the control of Congress to the Republican Party and the loss by his vice president Al Gore in the 2000 presidential election.
### Review Questions
### Critical Thinking Questions
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# The Challenges of the Twenty-First Century
## Introduction
On the morning of September 11, 2001, hopes that the new century would leave behind the conflicts of the previous one were dashed when two hijacked airliners crashed into the twin towers of New York’s World Trade Center. When the first plane struck the north tower, many assumed that the crash was a horrific accident. But then a second plane hit the south tower less than thirty minutes later. People on the street watched in horror, as some of those trapped in the burning buildings jumped to their deaths and the enormous towers collapsed into dust. In the photo above, the Statue of Liberty appears to look on helplessly, as thick plumes of smoke obscure the Lower Manhattan skyline (). The events set in motion by the September 11 attacks would raise fundamental questions about the United States’ role in the world, the extent to which privacy should be protected at the cost of security, the definition of exactly who is an American, and the cost of liberty. |
# The Challenges of the Twenty-First Century
## The War on Terror
As a result of the narrow decision of the U.S. Supreme Court in Bush v. Gore, Republican George W. Bush was the declared the winner of the 2000 presidential election with a majority in the Electoral College of 271 votes to 266, although he received approximately 540,000 fewer popular votes nationally than his Democratic opponent, Bill Clinton’s vice president, Al Gore. Bush had campaigned with a promise of “compassionate conservatism” at home and nonintervention abroad. These platform planks were designed to appeal to those who felt that the Clinton administration’s initiatives in the Balkans and Africa had unnecessarily entangled the United States in the conflicts of foreign nations. Bush’s 2001 education reform act, dubbed No Child Left Behind, had strong bipartisan support and reflected his domestic interests. But before the president could sign the bill into law, the world changed when four American airliners were hijacked and used in the single most deadly act of terrorism in the United States. Bush’s domestic agenda quickly took a backseat, as the president swiftly changed course from nonintervention in foreign affairs to a “war on terror.”
### 9/11
Shortly after takeoff on the morning of September 11, 2001, teams of hijackers from the Islamist terrorist group al-Qaeda seized control of four American airliners. Two of the airplanes were flown into the twin towers of the World Trade Center in Lower Manhattan. Morning news programs that were filming the moments after the first impact, then assumed to be an accident, captured and aired live footage of the second plane, as it barreled into the other tower in a flash of fire and smoke. Less than two hours later, the heat from the crash and the explosion of jet fuel caused the upper floors of both buildings to collapse onto the lower floors, reducing both towers to smoldering rubble. The passengers and crew on both planes, as well as 2,606 people in the two buildings, all died, including 343 New York City firefighters who rushed in to save victims shortly before the towers collapsed.
The third hijacked plane was flown into the Pentagon building in northern Virginia, just outside Washington, DC, killing everyone on board and 125 people on the ground. The fourth plane, also heading towards Washington, crashed in a field near Shanksville, Pennsylvania, when passengers, aware of the other attacks, attempted to storm the cockpit and disarm the hijackers. Everyone on board was killed ().
That evening, President Bush promised the nation that those responsible for the attacks would be brought to justice. Three days later, Congress issued a joint resolution authorizing the president to use all means necessary against the individuals, organizations, or nations involved in the attacks. On September 20, in an address to a joint session of Congress, Bush declared war on terrorism, blamed al-Qaeda leader Osama bin Laden for the attacks, and demanded that the radical Islamic fundamentalists who ruled Afghanistan, the Taliban, turn bin Laden over or face attack by the United States. This speech encapsulated what became known as the Bush Doctrine, the belief that the United States has the right to protect itself from terrorist acts by engaging in pre-emptive wars or ousting hostile governments in favor of friendly, preferably democratic, regimes.
World leaders and millions of their citizens expressed support for the United States and condemned the deadly attacks. Russian president Vladimir Putin characterized them as a bold challenge to humanity itself. German chancellor Gerhard Schroder said the events of that day were “not only attacks on the people in the United States, our friends in America, but also against the entire civilized world, against our own freedom, against our own values, values which we share with the American people.” Yasser Arafat, chairman of the Palestinian Liberation Organization and a veteran of several bloody struggles against Israel, was dumbfounded by the news and announced to reporters in Gaza, “We completely condemn this very dangerous attack, and I convey my condolences to the American people, to the American president and to the American administration.”
### GOING TO WAR IN AFGHANISTAN
When it became clear that the mastermind behind the attack was Osama bin Laden, a wealthy Saudi Arabian national who ran his terror network from Afghanistan, the full attention of the United States turned towards Central Asia and the Taliban. Bin Laden had deep roots in Afghanistan. Like many others from around the Islamic world, he had come to the country to oust the Soviet army, which invaded Afghanistan in 1979. Ironically, both bin Laden and the Taliban received material support from the United States at that time. By the late 1980s, the Soviets and the Americans had both left, although bin Laden, by that time the leader of his own terrorist organization, al-Qaeda, remained.
The Taliban refused to turn bin Laden over, and the United States began a bombing campaign in October, allying with the Afghan Northern Alliance, a coalition of tribal leaders opposed to the Taliban. U.S. air support was soon augmented by ground troops (). By November 2001, the Taliban had been ousted from power in Afghanistan’s capital of Kabul, but bin Laden and his followers had already escaped across the Afghan border to mountain sanctuaries in northern Pakistan.
### IRAQ
At the same time that the U.S. military was taking control of Afghanistan, the Bush administration was looking to a new and larger war with the country of Iraq. Relations between the United States and Iraq had been strained ever since the Gulf War a decade earlier. Economic sanctions imposed on Iraq by the United Nations, and American attempts to foster internal revolts against President Saddam Hussein’s government, had further tainted the relationship. A faction within the Bush administration, sometimes labeled neoconservatives, believed Iraq’s recalcitrance in the face of overwhelming U.S. military superiority represented a dangerous symbol to terrorist groups around the world, recently emboldened by the dramatic success of the al-Qaeda attacks in the United States. Powerful members of this faction, including Vice President Dick Cheney and Secretary of Defense Donald Rumsfeld, believed the time to strike Iraq and solve this festering problem was right then, in the wake of 9/11. Others, like Secretary of State Colin Powell, a highly respected veteran of the Vietnam War and former chair of the Joint Chiefs of Staff, were more cautious about initiating combat.
The more militant side won, and the argument for war was gradually laid out for the American people. The immediate impetus to the invasion, it argued, was the fear that Hussein was stockpiling weapons of mass destruction (WMDs): nuclear, chemical, or biological weapons capable of wreaking great havoc. Hussein had in fact used WMDs against Iranian forces during his war with Iran in the 1980s, and against the Kurds in northern Iraq in 1988—a time when the United States actively supported the Iraqi dictator. Following the Gulf War, inspectors from the United Nations Special Commission and International Atomic Energy Agency had in fact located and destroyed stockpiles of Iraqi weapons. Those arguing for a new Iraqi invasion insisted, however, that weapons still existed. President Bush himself told the nation in October 2002 that the United States was “facing clear evidence of peril, we cannot wait for the final proof—the smoking gun—that could come in the form of a mushroom cloud.” The head of the United Nations Monitoring, Verification and Inspection Commission, Hanx Blix, dismissed these claims. Blix argued that while Saddam Hussein was not being entirely forthright, he did not appear to be in possession of WMDs. Despite Blix’s findings and his own earlier misgivings, Powell argued in 2003 before the United Nations General Assembly that Hussein had violated UN resolutions. Much of his evidence relied on secret information provided by an informant that was later proven to be false. On March 17, 2003, the United States cut off all relations with Iraq. Two days later, in a coalition with Great Britain, Australia, and Poland, the United States began “Operation Iraqi Freedom” with an invasion of Iraq.
Other arguments supporting the invasion noted the ease with which the operation could be accomplished. In February 2002, some in the Department of Defense were suggesting the war would be “a cakewalk.” In November, referencing the short and successful Gulf War of 1990–1991, Secretary of Defense Rumsfeld told the American people it was absurd, as some were claiming, that the conflict would degenerate into a long, drawn-out quagmire. “Five days or five weeks or five months, but it certainly isn’t going to last any longer than that,” he insisted. “It won’t be a World War III.” And, just days before the start of combat operations in 2003, Vice President Cheney announced that U.S. forces would likely “be greeted as liberators,” and the war would be over in “weeks rather than months.”
Early in the conflict, these predictions seemed to be coming true. The march into Baghdad went fairly smoothly. Soon Americans back home were watching on television as U.S. soldiers and the Iraqi people worked together to topple statues of the deposed leader Hussein around the capital. The reality, however, was far more complex. While American deaths had been few, thousands of Iraqis had died, and the seeds of internal strife and resentment against the United States had been sown. The United States was not prepared for a long period of occupation; it was also not prepared for the inevitable problems of law and order, or for the violent sectarian conflicts that emerged. Thus, even though Bush proclaimed a U.S. victory in May 2003, on the deck of the USS Abraham Lincoln with the banner “Mission Accomplished” prominently displayed behind him, the celebration proved premature by more than seven years ().
### DOMESTIC SECURITY
The attacks of September 11 awakened many to the reality that the end of the Cold War did not mean an end to foreign violent threats. Some Americans grew wary of alleged possible enemies in their midst and hate crimes against Muslim Americans—and those thought to be Muslims—surged in the aftermath. Fearing that terrorists might strike within the nation’s borders again, and aware of the chronic lack of cooperation among different federal law enforcement agencies, Bush created the Office of Homeland Security in October 2001. The next year, Congress passed the Homeland Security Act, creating the Department of Homeland Security, which centralized control over a number of different government functions in order to better control threats at home (). The Bush administration also pushed the USA Patriot Act through Congress, which enabled law enforcement agencies to monitor citizens’ e-mails and phone conversations without a warrant.
The Bush administration was fiercely committed to rooting out threats to the United States wherever they originated, and in the weeks after September 11, the Central Intelligence Agency (CIA) scoured the globe, sweeping up thousands of young Muslim men. Because U.S. law prohibits the use of torture, the CIA transferred some of these prisoners to other nations—a practice known as rendition or extraordinary rendition—where the local authorities can use methods of interrogation not allowed in the United States.
While the CIA operates overseas, the Federal Bureau of Investigation (FBI) is the chief federal law enforcement agency within U.S. national borders. Its activities are limited by, among other things, the Fourth Amendment, which protects citizens against unreasonable searches and seizures. Beginning in 2002, however, the Bush administration implemented a wide-ranging program of warrantless domestic wiretapping, known as the Terrorist Surveillance Program, by the National Security Agency (NSA). The shaky constitutional basis for this program was ultimately revealed in August 2006, when a federal judge in Detroit ordered the program ended immediately.
The use of unconstitutional wire taps to prosecute the war on terrorism was only one way the new threat challenged authorities in the United States. Another problem was deciding what to do with foreign terrorists captured on the battlefields in Afghanistan and Iraq. In traditional conflicts, where both sides are uniformed combatants, the rules of engagement and the treatment of prisoners of war are clear. But in the new war on terror, extracting intelligence about upcoming attacks became a top priority that superseded human rights and constitutional concerns. For that purpose, the United States began transporting men suspected of being members of al-Qaeda to the U.S. naval base at Guantanamo Bay, Cuba, for questioning. The Bush administration labeled the detainees “unlawful combatants,” in an effort to avoid affording them the rights guaranteed to prisoners of war, such as protection from torture, by international treaties such as the Geneva Conventions. Furthermore, the Justice Department argued that the prisoners were unable to sue for their rights in U.S. courts on the grounds that the constitution did not apply to U.S. territories. It was only in 2006 that the Supreme Court ruled in Hamdan v. Rumsfeld that the military tribunals that tried Guantanamo prisoners violated both U.S. federal law and the Geneva Conventions.
### Section Summary
George W. Bush’s first term in office began with al-Qaeda’s deadly attacks on the World Trade Center and the Pentagon on September 11, 2001. Shortly thereafter, the United States found itself at war with Afghanistan, which was accused of harboring the 9/11 mastermind, Osama bin Laden, and his followers. Claiming that Iraq’s president Saddam Hussein was building weapons of mass destruction, perhaps with the intent of attacking the United States, the president sent U.S. troops to Iraq as well in 2003. Thousands were killed, and many of the men captured by the United States were imprisoned and sometimes tortured for information. The ease with which Hussein was deposed led the president to declare that the mission in Iraq had been accomplished only a few months after it began. He was, however, mistaken. Meanwhile, the establishment of the Office of Homeland Security and the passage of the Homeland Security Act and USA Patriot Act created new means and levels of surveillance to identify potential threats.
### Review Questions
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# The Challenges of the Twenty-First Century
## The Domestic Mission
By the time George W. Bush became president, the concept of supply-side economics had become an article of faith within the Republican Party. The oft-repeated argument was that tax cuts for the wealthy would allow them to invest more and create jobs for everyone else. This belief in the self-regulatory powers of competition also served as the foundation of Bush’s education reform. But by the end of 2008, however, Americans’ faith in the dynamics of the free market had been badly shaken. The failure of the homeland security apparatus during Hurricane Katrina and the ongoing challenge of the Iraq War compounded the effects of the bleak economic situation.
### OPENING AND CLOSING THE GAP
The Republican Party platform for the 2000 election offered the American people an opportunity to once again test the rosy expectations of supply-side economics. In 2001, Bush and the Republicans pushed through a $1.35 trillion tax cut by lowering tax rates across the board but reserving the largest cuts for those in the highest tax brackets. This was in the face of calls by Republicans for a balanced budget, which Bush insisted would happen when the so-called job creators expanded the economy by using their increased income to invest in business.
The cuts were controversial; the rich were getting richer while the middle and lower classes bore a proportionally larger share of the nation’s tax burden. Between 1966 and 2001, one-half of the nation’s income gained from increased productivity went to the top 0.01 percent of earners. By 2005, dramatic examples of income inequity were increasing; the chief executive of Wal-Mart earned $15 million that year, roughly 950 times what the company’s average associate made. The head of the construction company K. B. Homes made $150 million, or four thousand times what the average construction worker earned that same year. Even as productivity climbed, workers’ incomes stagnated; with a larger share of the wealth, the very rich further solidified their influence on public policy. Left with a smaller share of the economic pie, average workers had fewer resources to improve their lives or contribute to the nation’s prosperity by, for example, educating themselves and their children.
Another gap that had been widening for years was the education gap. Some education researchers had argued that American students were being left behind. In 1983, a commission established by Ronald Reagan had published a sobering assessment of the American educational system entitled A Nation at Risk. The report argued that American students were more poorly educated than their peers in other countries, especially in areas such as math and science, and were thus unprepared to compete in the global marketplace. Furthermore, test scores revealed serious educational achievement gaps between White students and students of color. Touting himself as the “education president,” Bush sought to introduce reforms that would close these gaps.
His administration offered two potential solutions to these problems. First, it sought to hold schools accountable for raising standards and enabling students to meet them. The No Child Left Behind Act, signed into law in January 2002, erected a system of testing to measure and ultimately improve student performance in reading and math at all schools that received federal funds (). Schools whose students performed poorly on the tests would be labeled “in need of improvement.” If poor performance continued, schools could face changes in curricula and teachers, or even the prospect of closure.
The second proposed solution was to give students the opportunity to attend schools with better performance records. Some of these might be charter schools, institutions funded by local tax monies in much the same way as public schools, but able to accept private donations and exempt from some of the rules public schools must follow. During the administration of George H. W. Bush, the development of charter schools had gathered momentum, and the American Federation of Teachers welcomed them as places to employ innovative teaching methods or offer specialized instruction in particular subjects. President George W. Bush now encouraged states to grant educational funding vouchers to parents, who could use them to pay for a private education for their children if they chose. These vouchers were funded by tax revenue that would otherwise have gone to public schools.
### THE 2004 ELECTION AND BUSH’S SECOND TERM
In the wake of the 9/11 attacks, Americans had rallied around their president in a gesture of patriotic loyalty, giving Bush approval ratings of 90 percent. Even following the first few months of the Iraq war, his approval rating remained historically high at approximately 70 percent. But as the 2004 election approached, opposition to the war in Iraq began to grow. While Bush could boast of a number of achievements at home and abroad during his first term, the narrow victory he achieved in 2000 augured poorly for his chances for reelection in 2004 and a successful second term.
### Reelection
As the 2004 campaign ramped up, the president was persistently dogged by rising criticism of the violence of the Iraq war and the fact that his administration’s claims of WMDs had been greatly overstated. In the end, no such weapons were ever found. These criticisms were amplified by growing international concern over the treatment of prisoners at the Guantanamo Bay detention camp and widespread disgust over the torture conducted by U.S. troops at the prison in Abu Ghraib, Iraq, which surfaced only months before the election ().
In March 2004, an ambush by Iraqi insurgents of a convoy of private military contractors from Blackwater USA in the town of Fallujah west of Baghdad, and the subsequent torture and mutilation of the four captured mercenaries, shocked the American public. But the event also highlighted the growing insurgency against U.S. occupation, the escalating sectarian conflict between the newly empowered Shia Muslims and the minority of the formerly ruling Sunni, and the escalating costs of a war involving a large number of private contractors that, by conservative estimates, approached $1.7 trillion by 2013. Just as importantly, the American campaign in Iraq had diverted resources from the war against al-Qaeda in Afghanistan, where U.S troops were no closer to capturing Osama bin Laden, the mastermind behind the 9/11 attacks.
With two hot wars overseas, one of which appeared to be spiraling out of control, the Democrats nominated a decorated Vietnam War veteran, Massachusetts senator John Kerry (), to challenge Bush for the presidency. As someone with combat experience, three Purple Hearts, and a foreign policy background, Kerry seemed like the right challenger in a time of war. But his record of support for the invasion of Iraq made his criticism of the incumbent less compelling and earned him the byname “Waffler” from Republicans. The Bush campaign also sought to characterize Kerry as an elitist out of touch with regular Americans—Kerry had studied overseas, spoke fluent French, and married a wealthy foreign-born heiress. Republican supporters also unleashed an attack on Kerry’s Vietnam War record, falsely claiming he had lied about his experience and fraudulently received his medals. Kerry’s reluctance to embrace his past leadership of Vietnam Veterans Against the War weakened the enthusiasm of antiwar Americans while opening him up to criticisms from veterans groups. This combination compromised the impact of his challenge to the incumbent in a time of war.
Urged by the Republican Party to “stay the course” with Bush, voters listened. Bush won another narrow victory, and the Republican Party did well overall, picking up four seats in the Senate and increasing its majority there to fifty-five. In the House, the Republican Party gained three seats, adding to its majority there as well. Across the nation, most governorships also went to Republicans, and Republicans dominated many state legislatures.
Despite a narrow win, the president made a bold declaration in his first news conference following the election. “I earned capital in this campaign, political capital, and now I intend to spend it.” The policies on which he chose to spend this political capital included the partial privatization of Social Security and new limits on court-awarded damages in medical malpractice lawsuits. In foreign affairs, Bush promised that the United States would work towards “ending tyranny in the world.” But at home and abroad, the president achieved few of his second-term goals. Instead, his second term in office became associated with the persistent challenge of pacifying Iraq, the failure of the homeland security apparatus during Hurricane Katrina, and the most severe economic crisis since the Great Depression.
### A Failed Domestic Agenda
The Bush administration had planned a series of free-market reforms, but corruption, scandals, and Democrats in Congress made these goals hard to accomplish. Plans to convert Social Security into a private-market mechanism relied on the claim that demographic trends would eventually make the system unaffordable for the shrinking number of young workers, but critics countered that this was easily fixed. Privatization, on the other hand, threatened to derail the mission of the New Deal welfare agency and turn it into a fee generator for stock brokers and Wall Street financiers. Similarly unpopular was the attempt to abolish the estate tax. Labeled the “death tax” by its critics, its abolishment would have benefitted only the wealthiest 1 percent. As a result of the 2003 tax cuts, the growing federal deficit did not help make the case for Republicans.
The nation faced another policy crisis when the Republican-dominated House of Representatives approved a bill making the undocumented status of millions of immigrants a felony and criminalizing the act of employing or knowingly aiding undocumented immigrants. In response, millions of immigrants, along with other critics of the bill, took to the streets in protest. What they saw as the civil rights challenge of their generation, conservatives read as a dangerous challenge to law and national security. Congress eventually agreed on a massive build-up of the U.S. Border Patrol and the construction of a seven-hundred-mile-long fence along the border with Mexico, but the deep divisions over immigration and the status of up to twelve million undocumented immigrants remained unresolved.
### Hurricane Katrina
One event highlighted the nation’s economic inequality and racial divisions, as well as the Bush administration’s difficulty in addressing them effectively. On August 29, 2005, Hurricane Katrina came ashore and devastated coastal stretches of Alabama, Mississippi, and Louisiana. The city of New Orleans, no stranger to hurricanes and floods, suffered heavy damage when the levees, embankments designed to protect against flooding, failed during the storm surge, as the Army Corps of Engineers had warned they might. The flooding killed some fifteen hundred people and so overwhelmed parts of the city that tens of thousands more were trapped and unable to evacuate (). Thousands who were elderly, ill, or too poor to own a car followed the mayor’s directions and sought refuge at the Superdome, which lacked adequate food, water, and sanitation. Public services collapsed under the weight of the crisis.
Although the U.S. Coast Guard managed to rescue more than thirty-five thousand people from the stricken city, the response by other federal bodies was less effective. The Federal Emergency Management Agency (FEMA), an agency charged with assisting state and local governments in times of natural disaster, proved inept at coordinating different agencies and utilizing the rescue infrastructure at its disposal. Critics argued that FEMA was to blame and that its director, Michael D. Brown, a Bush friend and appointee with no background in emergency management, was an example of cronyism at its worst. The failures of FEMA were particularly harmful for an administration that had made “homeland security” its top priority. Supporters of the president, however, argued that the scale of the disaster was such that no amount of preparedness or competence could have allowed federal agencies to cope.
While there was plenty of blame to go around—at the city, state, and national levels—FEMA and the Bush administration got the lion’s share. Even when the president attempted to demonstrate his concern with a personal appearance, the tactic largely backfired. Photographs of him looking down on a flooded New Orleans from the comfort of Air Force One only reinforced the impression of a president detached from the problems of everyday people. Despite his attempts to give an uplifting speech from Jackson Square, he was unable to shake this characterization, and it underscored the disappointments of his second term. On the eve of the 2006 midterm elections, President Bush’s popularity had reached a new low, as a result of the war in Iraq and Hurricane Katrina, and a growing number of Americans feared that his party’s economic policy benefitted the wealthy first and foremost. Young voters, non-White Americans, and women favored the Democratic ticket by large margins. The elections handed Democrats control of the Senate and House for the first time since 1994, and, in January 2007, California representative Nancy Pelosi became the first female Speaker of the House in the nation’s history.
### THE GREAT RECESSION
For most Americans, the millennium had started with economic woes. In March 2001, the U.S. stock market had taken a sharp drop, and the ensuing recession triggered the loss of millions of jobs over the next two years. In response, the Federal Reserve Board cut interest rates to historic lows to encourage consumer spending. By 2002, the economy seemed to be stabilizing somewhat, but few of the manufacturing jobs lost were restored to the national economy. Instead, the “outsourcing” of jobs to China and India became an increasing concern, along with a surge in corporate scandals. After years of reaping tremendous profits in the deregulated energy markets, Houston-based Enron imploded in 2003 over allegations of massive accounting fraud. Its top executives, Ken Lay and Jeff Skilling, received long prison sentences, but their activities were illustrative of a larger trend in the nation’s corporate culture that embroiled reputable companies like JP Morgan Chase and the accounting firm Arthur Anderson. In 2003, Bernard Ebbers, the CEO of communications giant WorldCom, was discovered to have inflated his company’s assets by as much as $11 billion, making it the largest accounting scandal in the nation’s history. Only five years later, however, Bernard Madoff’s Ponzi scheme would reveal even deeper cracks in the nation’s financial economy.
### Banks Gone Wild
Notwithstanding economic growth in the 1990s and steadily increasing productivity, wages had remained largely flat relative to inflation since the end of the 1970s; despite the mild recovery, they remained so. To compensate, many consumers were buying on credit, and with interest rates low, financial institutions were eager to oblige them. By 2008, credit card debt had risen to over $1 trillion. More importantly, banks were making high-risk, high-interest mortgage loans called subprime mortgages to consumers who often misunderstood their complex terms and lacked the ability to make the required payments.
These subprime loans had a devastating impact on the larger economy. In the past, a prospective home buyer went to a local bank for a mortgage loan. Because the bank expected to make a profit in the form of interest charged on the loan, it carefully vetted buyers for their ability to repay. Changes in finance and banking laws in the 1990s and early 2000s, however, allowed lending institutions to securitize their mortgage loans and sell them as bonds, thus separating the financial interests of the lender from the ability of the borrower to repay, and making highly risky loans more attractive to lenders. In other words, banks could afford to make bad loans, because they could sell them and not suffer the financial consequences when borrowers failed to repay.
Once they had purchased the loans, larger investment banks bundled them into huge packages known as collateralized debt obligations (CDOs) and sold them to investors around the world. Even though CDOs consisted of subprime mortgages, credit card debt, and other risky investments, credit ratings agencies had a financial incentive to rate them as very safe. Making matters worse, financial institutions created instruments called credit default swaps, which were essentially a form of insurance on investments. If the investment lost money, the investors would be compensated. This system, sometimes referred to as the securitization food chain, greatly swelled the housing loan market, especially the market for subprime mortgages, because these loans carried higher interest rates. The result was a housing bubble, in which the value of homes rose year after year based on the ease with which people now could buy them.
### Banks Gone Broke
When the real estate market stalled after reaching a peak in 2007, the house of cards built by the country’s largest financial institutions came tumbling down. People began to default on their loans, and more than one hundred mortgage lenders went out of business. American International Group (AIG), a multinational insurance company that had insured many of the investments, faced collapse. Other large financial institutions, which had once been prevented by federal regulations from engaging in risky investment practices, found themselves in danger, as they either were besieged by demands for payment or found their demands on their own insurers unmet. The prestigious investment firm Lehman Brothers was completely wiped out in September 2008. Some endangered companies, like Wall Street giant Merrill Lynch, sold themselves to other financial institutions to survive. A financial panic ensued that revealed other fraudulent schemes built on CDOs. The biggest among them was a pyramid scheme organized by the New York financier Bernard Madoff, who had defrauded his investors by at least $18 billion.
Realizing that the failure of major financial institutions could result in the collapse of the entire U.S. economy, the chairman of the Federal Reserve, Ben Bernanke, authorized a bailout of the Wall Street firm Bear Stearns, although months later, the financial services firm Lehman Brothers was allowed to file for the largest bankruptcy in the nation’s history. Members of Congress met with Bernanke and Secretary of the Treasury Henry Paulson in September 2008, to find a way to head off the crisis. They agreed to use $700 billion in federal funds to bail out the troubled institutions, and Congress subsequently passed the Emergency Economic Stabilization Act, creating the Troubled Asset Relief Program (TARP). One important element of this program was aid to the auto industry: The Bush administration responded to their appeal with an emergency loan of $17.4 billion—to be executed by his successor after the November election—to stave off the industry’s collapse.
The actions of the Federal Reserve, Congress, and the president prevented the complete disintegration of the nation’s financial sector and warded off a scenario like that of the Great Depression. However, the bailouts could not prevent a severe recession in the U.S. and world economy. As people lost faith in the economy, stock prices fell by 45 percent. Unable to receive credit from now-wary banks, smaller businesses found that they could not pay suppliers or employees. With houses at record prices and growing economic uncertainty, people stopped buying new homes. As the value of homes decreased, owners were unable to borrow against them to pay off other obligations, such as credit card debt or car loans. More importantly, millions of homeowners who had expected to sell their houses at a profit and pay off their adjustable-rate mortgages were now stuck in houses with values shrinking below their purchasing price and forced to make mortgage payments they could no longer afford.
Without access to credit, consumer spending declined. Some European nations had suffered similar speculation bubbles in housing, but all had bought into the mortgage securities market and suffered the losses of assets, jobs, and demand as a result. International trade slowed, hurting many American businesses. As the Great Recession of 2008 deepened, the situation of ordinary citizens became worse. During the last four months of 2008, one million American workers lost their jobs, and during 2009, another three million found themselves out of work. Under such circumstances, many resented the expensive federal bailout of banks and investment firms. It seemed as if the wealthiest were being rescued by the taxpayer from the consequences of their imprudent and even corrupt practices.
### Section Summary
When George W. Bush took office in January 2001, he was committed to a Republican agenda. He cut tax rates for the rich and tried to limit the role of government in people’s lives, in part by providing students with vouchers to attend charter and private schools, and encouraging religious organizations to provide social services instead of the government. While his tax cuts pushed the United States into a chronically large federal deficit, many of his supply-side economic reforms stalled during his second term. In 2005, Hurricane Katrina underscored the limited capacities of the federal government under Bush to assure homeland security. In combination with increasing discontent over the Iraq War, these events handed Democrats a majority in both houses in 2006. Largely as a result of a deregulated bond market and dubious innovations in home mortgages, the nation reached the pinnacle of a real estate boom in 2007. The threatened collapse of the nations’ banks and investment houses required the administration to extend aid to the financial sector. Many resented this bailout of the rich, as ordinary citizens lost jobs and homes in the Great Recession of 2008.
### Review Questions
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# The Challenges of the Twenty-First Century
## New Century, Old Disputes
As the United States entered the twenty-first century, old disputes continued to rear their heads. Some revolved around what it meant to be American and the rights to full citizenship. Others arose from religious conservatism and the influence of the Religious Right on American culture and society. Debates over gay and lesbian rights continued, and arguments over abortion became more complex and contentious, as science and technology advanced. The clash between faith and science also influenced attitudes about how the government should respond to climate change, with religious conservatives finding allies among political conservatives who favored business over potentially expensive measures to reduce harmful emissions.
### WHO IS AN AMERICAN?
There is nothing new about anxiety over immigration in the United States. For its entire history, citizens have worried about who is entering the country and the changes that might result. Such concerns began to flare once again beginning in the 1980s, as Americans of European ancestry started to recognize the significant demographic changes on the horizon. The number of Americans of color and multiethnic Americans was growing, as was the percentage of people with other than European ancestry. It was clear the White majority would soon be a demographic minority ().
The nation’s increasing diversity prompted some social conservatives to identify American culture as one of European heritage, including the drive to legally designate English the official language of the United States. This movement was particularly strong in areas of the country with large Spanish-speaking populations such as Arizona, where, in 2006, three-quarters of voters approved a proposition to make English the official language in the state. Proponents in Arizona and elsewhere argued that these laws were necessary, because recent immigrants, especially Hispanic newcomers, were not being sufficiently acculturated to White, middle-class culture. Opponents countered that English was already the de facto official language, and codifying it into law would only amount to unnecessary discrimination.
The fear that English-speaking Americans were being outnumbered by a Hispanic population that was not forced to assimilate was sharpened by the concern that far too many people were illegally emigrating from Latin America to the United States. The Comprehensive Immigration Reform Act proposed by Congress in 2006 sought to simultaneously strengthen security along the U.S.-Mexico border (a task for the Department of Homeland Security), increase the number of temporary “guest workers” allowed in the United States, and provide a pathway for long-term U.S. residents who had entered the country illegally to gain legal status. It also sought to establish English as a “common and unifying language” for the nation. The bill and a similar amended version both failed to become law.
With unemployment rates soaring during the Great Recession, anxiety over illegal immigration rose, even while the incoming flow slowed. State legislatures in Alabama and Arizona passed strict new laws that required police and other officials to verify the immigration status of those they thought had entered the country illegally. In Alabama, the new law made it a crime to rent housing to undocumented immigrants, thus making it difficult for these immigrants to live within the state. Both laws have been challenged in court, and portions have been deemed unconstitutional or otherwise blocked.
Beginning in October 2013, states along the U.S.-Mexico border faced an increase in the immigration of children from a handful of Central American countries. Approximately fifty-two thousand children, some unaccompanied, were taken into custody as they reached the United States. A study by the United Nations High Commissioner for Refugees estimated that 58 percent of those migrants, largely from El Salvador and Honduras, were propelled towards the United States by poverty, violence, and the potential for exploitation in their home countries. Because of a 2008 law originally intended to protect victims of human trafficking, these Central American children are guaranteed a court hearing. Predictably, the crisis has served to underline the need for comprehensive immigration reform. But a number of reform efforts and bills that combine border security with a guest worker program and a path to citizenship have yet to be enacted as law.
### WHAT IS A MARRIAGE?
In the 1990s, the idea of legal, same-sex marriage seemed particularly unlikely; neither of the two main political parties expressed support for it. Things began to change, however, following Vermont’s decision to allow same-sex couples to form state-recognized civil unions in which they could enjoy all the legal rights and privileges of marriage. Although it was the intention of the state to create a type of legal relationship equivalent to marriage, it did not use the word “marriage” to describe it.
Following Vermont’s lead, several other states legalized same-sex marriages or civil unions among gay and lesbian couples. In 2004, the Massachusetts Supreme Judicial Court ruled that barring gay and lesbian people from marrying violated the state constitution. The court held that offering same-sex couples the right to form civil unions but not marriage was an act of discrimination, and Massachusetts became the first state to allow same-sex couples to marry. Not all states followed suit, however, and there was a backlash in several states. Between 1998 and 2012, thirty states banned same-sex marriage either by statute or by amending their constitutions. Other states attempted, unsuccessfully, to do the same. In 2007, the Massachusetts State Legislature rejected a proposed amendment to the state’s constitution that would have prohibited such marriages.
While those in support of broadening civil rights to include same-sex marriage were optimistic, those opposed employed new tactics. In 2008, opponents of same-sex marriage in California tried a ballot initiative to define marriage strictly as a union between a man and a woman. Despite strong support for broadening marriage rights, the proposition was successful. This change was just one of dozens that states had been putting in place since the late 1990s to make same-sex marriage unconstitutional at the state level. Like the California proposition, however, many new state constitutional amendments have faced challenges in court (). As of 2014, leaders in both political parties are more receptive than ever before to the idea of same-sex marriage.
### WHY FIGHT CLIMATE CHANGE?
Even as mainstream members of both political parties moved closer together on same-sex marriage, political divisions on scientific debates continued. One increasingly polarizing debate that baffles much of the rest of the world is about global climate change. Despite near unanimity in the scientific community that climate change is real and will have devastating consequences, large segments of the American population, predominantly on the right, continue to insist that it is little more than a complex hoax and a leftist conspiracy. Much of the Republican Party’s base denies that global warming is the result of human activity; some deny that the earth is getting hotter at all. This popular denial has had huge global consequences. In 1998, the United States, which produces roughly 36 percent of the greenhouse gases like carbon dioxide that prevent the earth’s heat from escaping into space, signed the Kyoto Protocol, an agreement among the world’s nations to reduce their emissions of these gases. President Bush objected to the requirement that major industrialized nations limit their emissions to a greater extent than other parts of the world and argued that doing so might hurt the American economy. He announced that the United States would not be bound by the agreement, and it was never ratified by Congress.
Instead, the Bush administration appeared to suppress scientific reporting on climate change. In 2006, the progressive-leaning Union of Concerned Scientists surveyed sixteen hundred climate scientists, asking them about the state of federal climate research. Of those who responded, nearly three-fourths believed that their research had been subjected to new administrative requirements, third-party editing to change their conclusions, or pressure not to use terms such as “global warming.” Republican politicians, citing the altered reports, argued that there was no unified opinion among members of the scientific community that humans were damaging the climate.
Countering this rejection of science were the activities of many environmentalists, including Al Gore, Clinton’s vice president and Bush’s opponent in the disputed 2000 election. As a new member of Congress in 1976, Gore had developed what proved a steady commitment to environmental issues. In 2004, he established Generation Investment Management, which sought to promote an environmentally responsible system of equity analysis and investment. In 2006, a documentary film, An Inconvenient Truth, represented his attempts to educate people about the realities and dangers of global warming, and won the 2007 Academy Award for Best Documentary. Though some of what Gore said was in error, the film’s main thrust is in keeping with the weight of scientific evidence. In 2007, as a result of these efforts to “disseminate greater knowledge about man-made climate change,” Gore shared the Nobel Peace Prize with the Intergovernmental Panel on Climate Change.
### Section Summary
The nation’s increasing diversity—and with it, the fact that White Caucasians will soon be a demographic minority—prompted a conservative backlash that continues to manifest itself in debates about immigration. Questions of who is an American and what constitutes a marriage continue to be debated, although the answers are beginning to change. As some states broadened civil rights to include gays and lesbians, groups opposed to these developments sought to impose state constitutional restrictions. From this flurry of activity, however, a new political consensus for expanding marriage rights has begun to emerge. On the issue of climate change, however, polarization has increased. A strong distrust of science among Americans has divided the political parties and hampered scientific research.
### Review Questions
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# The Challenges of the Twenty-First Century
## Hope and Change
In 2008, American voters, tired of war and dispirited by the economic downturn, elected a relative newcomer to the political scene who inspired them and made them believe that the United States could rise above political partisanship. Barack Obamas story resembled that of many Americans: a multicultural background; a largely absent father; a single working mother; and care provided by maternal grandparents. As president, Obama would face significant challenges, including managing the economic recovery in the wake of the Great Recession, fighting the war on terror inherited from the previous administration, and implementing the healthcare reform upon which he had campaigned.
### OBAMA TAKES OFFICE
Born in Hawaii in 1961 to a Kenyan father and an American woman from Kansas, Obama excelled at school, going on to attend Occidental College in Los Angeles, Columbia University, and finally Harvard Law School, where he became the first African American president of the Harvard Law Review. As part of his education, he also spent time in Chicago working as a community organizer to help those displaced by the decline of heavy industry in the early 1980s. Obama first came to national attention when he delivered the keynote address at the 2004 Democratic National Convention while running for his first term in the U.S. Senate. Just a couple of years later, he was running for president himself, the first African American nominee for the office from either major political party.
Obamas opponent in 2008 was John McCain, a Vietnam veteran and Republican senator with the reputation of a maverick who had occasionally broken ranks with his party to support bipartisan initiatives. The senator from Arizona faced a number of challenges. As the Republican nominee, he remained closely associated with the two disastrous foreign wars initiated under the Bush administration. His late recognition of the economic catastrophe on the eve of the election did not help matters and further damaged the Republican brand at the polls. At seventy-one, he also had to fight accusations that he was too old for the job, an impression made even more striking by his energetic young challenger. To minimize this weakness, McCain chose a young but inexperienced running mate, Governor Sarah Palin of Alaska. This tactic backfired, however, when a number of poor performances in television interviews convinced many voters that Palin was not prepared for higher office ().
Senator Obama, too, was criticized for his lack of experience with foreign policy, a deficit he remedied by choosing experienced politician Joseph Biden as his running mate. Unlike his Republican opponent, however, Obama offered promises of hope and change. By sending out voter reminders on Twitter and connecting with supporters on Facebook, he was able to harness social media and take advantage of grassroots enthusiasm for his candidacy. His youthful vigor drew independents and first-time voters, and he won 95 percent of the African American vote and 44 percent of the White vote ().
### ECONOMIC AND HEALTHCARE REFORMS
Barack Obama had been elected on a platform of healthcare reform and a wave of frustration over the sinking economy. As he entered office in 2009, he set out to deal with both. Taking charge of the TARP program instituted under George W. Bush to stabilize the countrys financial institutions, Obama oversaw the distribution of some $7.77 trillion designed to help shore up the nations banking system. Recognizing that the economic downturn also threatened major auto manufacturers in the United States, he sought and received congressional authorization for $80 billion to help Chrysler and General Motors. The action was controversial, and some characterized it as a government takeover of industry. The money did, however, help the automakers earn a profit by 2011, reversing the trend of consistent losses that had hurt the industry since 2004. It also helped prevent layoffs and wage cuts. By 2013, the automakers had repaid over $50 billion of bailout funds. Finally, through the 2009 American Recovery and Reinvestment Act (ARRA), the Obama administration pumped almost $800 billion into the economy to stimulate economic growth and job creation.
More important for Obama supporters than his attempts to restore the economy was that he fulfill his promise to enact comprehensive healthcare reform. Many assumed such reforms would move quickly through Congress, since Democrats had comfortable majorities in both houses, and both Obama and McCain had campaigned on healthcare reform. However, as had occurred years before during President Clintons first term, opposition groups saw attempts at reform as an opportunity to put the political brakes on the Obama presidency. After months of political wrangling and condemnations of the healthcare reform plan as socialism, the Patient Protection and Affordable Care Act () was passed and signed into law.
The act, which created the program known as Obamacare, represented the first significant overhaul of the American healthcare system since the passage of Medicaid in 1965. Its goals were to provide all Americans with access to affordable health insurance, to require that everyone in the United States acquire some form of health insurance, and to lower the costs of healthcare. The plan, which made use of government funding, created private insurance company exchanges to market various insurance packages to enrollees.
Although the plan implemented the market-based reforms that they had supported for years, Republicans refused to vote for it. Following its passage, they called numerous times for its repeal, and more than twenty-four states sued the federal government to stop its implementation. Discontent over the Affordable Care Act helped the Republicans capture the majority in the House of Representatives in the 2010 midterm elections. It also helped spawn the Tea Party, a conservative movement focused primarily on limiting government spending and the size of the federal government.
### THE ELECTION OF 2012
By the 2012 presidential election, the Republicans, convinced Obama was vulnerable because of opposition to his healthcare program and a weak economy, nominated Mitt Romney, a well-known business executive-turned politician who had earlier signed healthcare reform into state law as governor of Massachusetts (). Romney had unsuccessfully challenged McCain for the Republican nomination in 2008, but by 2012, he had remade himself politically by moving towards the partys right wing and its newly created Tea Party faction, which was pulling the traditional conservative base further to the right with its strong opposition to abortion, gun control, and immigration.
Romney appealed to a new attitude within the Republican Party. While the percentage of Democrats who agreed that the government should help people unable to provide for themselves had remained relatively stable from 1987 to 2012, at roughly 75 to 79 percent, the percentage of Republicans who felt the same way had decreased from 62 to 40 percent over the same period, with the greatest decline coming after 2007. Indeed, Romney himself revealed his disdain for people on the lower rungs of the socioeconomic ladder when, at a fundraising event attended by affluent Republicans, he remarked that he did not care to reach the 47 percent of Americans who would always vote for Obama because of their dependence on government assistance. In his eyes, this low-income portion of the population preferred to rely on government social programs instead of trying to improve their own lives.
Starting out behind Obama in the polls, Romney significantly closed the gap in the first of three presidential debates, when he moved towards more centrist positions on many issues. Obama regained momentum in the remaining two debates and used his bailout of the auto industry to appeal to voters in the key states of Michigan and Ohio. Romneys remarks about the 47 percent hurt his position among both poor Americans and those who sympathized with them. A long-time critic of FEMA who claimed that it should be eliminated, Romney also likely lost votes in the Northeast when, a week before the election, Hurricane Sandy devastated the New England, New York, and New Jersey coasts. Obama and the federal government had largely rebuilt FEMA since its disastrous showing in New Orleans in 2005, and the agency quickly swung into action to assist the 8.5 million people affected by the disaster.
Obama won the election, but the Republicans retained their hold on the House of Representatives and the Democratic majority in the Senate grew razor-thin. Political bickering and intractable Republican resistance, including a 70 percent increase in filibusters over the 1980s, a refusal to allow a vote on some legislation, such as the 2012 jobs bill, and the glacial pace at which the Senate confirmed the Presidents judicial nominations, created political gridlock in Washington, interfering with Obamas ability to secure any important legislative victories.
### ONGOING CHALLENGES
As Obama entered his second term in office, the economy remained stagnant in many areas. On average, American students continued to fall behind their peers in the rest of the world, and the cost of a college education became increasingly unaffordable for many. Problems continued overseas in Iraq and Afghanistan, and another act of terrorism took place on American soil when bombs exploded at the 2013 Boston Marathon. At the same time, the cause of same-sex marriage made significant advances, and Obama was able to secure greater protection for the environment. He raised fuel-efficiency standards for automobiles to reduce the emissions of greenhouse gases and required coal-burning power plants to capture their carbon emissions.
### Learning and Earning
The quality of American education remains a challenge. The global economy is dominated by those nations with the greatest number of knowledge workers: people with specialized knowledge and skills like engineers, scientists, doctors, teachers, financial analysts, and computer programmers. Furthermore, American students reading, math, and critical thinking skills are less developed than those of their peers in other industrialized nations, including small countries like Estonia.
The Obama administration sought to make higher education more accessible by increasing the amount that students could receive under the federally funded Pell Grant Program, which, by the 201213 academic year, helped 9.5 million students pay for their college education. Obama also worked out a compromise with Congress in 2013, which lowered the interest rates charged on student loans. However, college tuition is still growing at a rate of 2 to 3 percent per year, and the debt burden has surpassed the $1 trillion mark and is likely to increase. With debt upon graduation averaging about $29,000, students may find their economic options limited. Instead of buying cars or paying for housing, they may have to join the boomerang generation and return to their parents homes in order to make their loan payments. Clearly, high levels of debt will affect their career choices and life decisions for the foreseeable future.
Many other Americans continue to be challenged by the state of the economy. Most economists calculate that the Great Recession reached its lowest point in 2009, and the economy has gradually improved since then. The stock market ended 2013 at historic highs, having experienced its biggest percentage gain since 1997. However, despite these gains, the nation struggled to maintain a modest annual growth rate of 2.5 percent after the Great Recession, and the percentage of the population living in poverty continues to hover around 15 percent. Income has decreased (), and, as late as 2011, the unemployment rate was still high in some areas. Eight million full-time workers have been forced into part-time work, whereas 26 million seem to have given up and left the job market.
### LGBTQ Rights
During Barack Obamas second term in office, courts began to counter efforts by conservatives to outlaw same-sex marriage. A series of decisions declared nine states prohibitions against same-sex marriage to be unconstitutional, and the Supreme Court rejected an attempt to overturn a federal court ruling to that effect in California in June 2013. Shortly thereafter, the Supreme Court also ruled that the Defense of Marriage Act of 1996 was unconstitutional, because it violated the Equal Protection Clause of the Fourteenth Amendment. These decisions seem to allow legal challenges in all the states that persist in trying to block same-sex unions.
The struggle against discrimination based on gender identity has also won some significant victories. In 2014, the U.S. Department of Education ruled that schools receiving federal funds may not discriminate against transgender students, and a board within the Department of Health and Human Services decided that Medicare should cover sexual reassignment surgery. Although very few people eligible for Medicare are transgender, the decision is still important, because private insurance companies often base their coverage on what Medicare considers appropriate and necessary forms of treatment for various conditions. Undoubtedly, the fight for greater rights for LGBTQ individuals will continue.
### Violence
Another running debate questions the easy accessibility of firearms. Between the spring of 1999, when two teens killed twelve of their classmates, a teacher, and themselves at their high school in Columbine, Colorado, and the early summer of 2014, fifty-two additional shootings or attempted shootings had occurred at schools (). Nearly always, the violence was perpetrated by young people with severe mental health problems, as at Sandy Hook elementary school in Newtown, Connecticut, in 2012. After killing his mother at home, twenty-year-old Adam Lanza went to the school and fatally shot twenty six- and seven-year-old students, along with six adult staff members, before killing himself. Advocates of stricter gun control noted a clear relationship between access to guns and mass shootings. Gun rights advocates, however, disagreed. They argued that access to guns is merely incidental.
Another shocking act of violence was the attack on the Boston Marathon. On April 15, 2013, shortly before 3:00 p.m., two bombs made from pressure cookers exploded near the finish line (). Three people were killed, and more than 250 were injured. Three days later, two suspects were identified, and a manhunt began. Later that night, the two young men, brothers who had immigrated to the United States from Chechnya, killed a campus security officer at the Massachusetts Institute of Technology, stole a car, and fled. The older, Tamerlan Tsarnaev, was killed in a fight with the police, and Dzhokhar Tsarnaev was captured the next day. In his statements to the police, Dzhokhar Tsarnaev reported that he and his brother, who he claimed had planned the attacks, had been influenced by the actions of fellow radical Islamists in Afghanistan and Iraq, but he denied they had been affiliated with any larger terrorist group.
### America and the World
In May 2014, President Obama announced that, for the most part, U.S. combat operations in Afghanistan were over. Although a residual force of ninety-eight hundred soldiers will remain to continue training the Afghan army, by 2016, all U.S. troops will have left the country, except for a small number to defend U.S. diplomatic posts.
The years of warfare have brought the United States few rewards. In Iraq, 4,475 American soldiers died and 32,220 were wounded. In Afghanistan, the toll through February 2013 was 2,165 dead and 18,230 wounded. By some estimates, the total monetary cost of the wars in Iraq and Afghanistan could easily reach $4 trillion, and the Congressional Budget Office believes that the cost of providing medical care for the veterans might climb to $8 billion by 2020.
In Iraq, the coalition led by then-Prime Minister Nouri al-Maliki was able to win 92 of the 328 seats in parliament in May 2014, and he seemed poised to begin another term as the countrys ruler. The elections, however, did not stem the tide of violence in the country. In June 2014, the Islamic State of Iraq and Syria (ISIS), a radical Islamist militant group consisting of mostly Sunni Muslims and once affiliated with al-Qaeda, seized control of Sunni-dominated areas of Iraq and Syria. On June 29, 2014, it proclaimed the formation of the Islamic State with Abu Bakr al-Baghdadi as caliph, the states political and religious leader.
### Section Summary
Despite Republican resistance and political gridlock in Washington during his first term in office, President Barack Obama oversaw the distribution of the TARP programs $7.77 trillion to help shore up the nations banking system, and Congress authorized $80 billion to help Chrysler and General Motors. The goals of Obamas Patient Protection and Affordable Care Act (Obamacare) were to provide all Americans with access to affordable health insurance, to require that everyone in the United States had some form of health insurance, and to lower the costs of healthcare. During his second term, the nation struggled to grow modestly, the percentage of the population living in poverty remained around 15 percent, and unemployment was still high in some areas. Acceptance of same-sex marriage grew, and the United States sharply reduced its military commitments in Iraq and Afghanistan.
### Review Questions
### Critical Thinking Questions
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# Ideas esenciales
## Introducción
Suena el despertador y, después de darle al botón de “posponer" una o dos veces, se levanta de la cama. Se prepara una taza de café para ponerse en marcha y luego se ducha, se viste, desayuna y comprueba si hay mensajes en su teléfono. De camino a la escuela, se detiene a llenar el tanque de gasolina de su automóvil, lo que hace que casi llegue tarde al primer día de clase de Química. Mientras encuentra un asiento en el aula, lee la pregunta proyectada en la pantalla: “¡Bienvenidos a la clase! ¿Por qué debemos estudiar química?”.
¿Tiene una respuesta? Puede que estudie química porque cumple un requisito académico, pero si tiene en cuenta sus actividades cotidianas, puede que la química le resulte interesante por otras razones. Casi todo lo que se hace y se encuentra durante el día tiene que ver con la química. Hacer café, cocer huevos y tostar el pan es algo que tiene que ver con la química. Los productos que utiliza, como el jabón y el champú, los tejidos que viste, los aparatos electrónicos que lo mantienen conectado al mundo, la gasolina que impulsa su automóvil, todos ellos y otros implican sustancias y procesos químicos. Tanto si es consciente como si no, la química forma parte de su mundo cotidiano. En este curso, aprenderá muchos de los principios esenciales que subyacen en la química de la vida moderna.
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# Ideas esenciales
## La química en su contexto
A lo largo de la historia de la humanidad, la gente ha intentado convertir la materia en formas más útiles. Nuestros antepasados de la Edad de Piedra tallaban trozos de sílex para convertirlos en herramientas útiles y tallaban madera para hacer estatuas y juguetes. Estos esfuerzos implicaban cambiar la forma de una sustancia sin cambiar la propia sustancia. Pero a medida que aumentaban nuestros conocimientos, los humanos empezaron a cambiar también la composición de las sustancias: la arcilla se convirtió en cerámica, las pieles se curaron para hacer prendas de vestir, los minerales de cobre se transformaron en herramientas y armas de cobre, y el grano se convirtió en pan.
Los seres humanos comenzaron a practicar la química cuando aprendieron a controlar el fuego y a utilizarlo para cocinar, fabricar cerámica y fundir metales. Posteriormente, comenzaron a separar y utilizar componentes específicos de la materia. De las plantas se aislaron diversas drogas, como el aloe, la mirra y el opio. Los tintes, como el índigo y la púrpura de Tiro, se extraían de la materia vegetal y animal. Los metales se combinaban para formar aleaciones (por ejemplo, el cobre y el estaño se mezclaban para hacer bronce) y las técnicas de fundición más elaboradas producían hierro. Los álcalis se extraían de las cenizas y los jabones se preparaban combinando estos álcalis con grasas. El alcohol se producía por fermentación y se purificaba por destilación.
Los intentos de comprender el comportamiento de la materia se remontan a más de 2500 años. Ya en el siglo VI a.C., los filósofos griegos discutían un sistema en el que el agua era la base de todas las cosas. Quizás haya oído hablar del postulado griego de que la materia está formada por cuatro elementos: tierra, aire, fuego y agua. Posteriormente, los alquimistas difundieron una amalgama de tecnologías químicas y especulaciones filosóficas desde Egipto, China y el Mediterráneo oriental, que se esforzaron por transformar "metales básicos" como el plomo en "metales nobles" como el oro, y por crear elíxires para curar enfermedades y alargar la vida ().
De la alquimia surgieron los avances históricos que condujeron a la química moderna: el aislamiento de fármacos a partir de fuentes naturales, como plantas y animales. Aunque muchas de las sustancias extraídas o procesadas de esas fuentes naturales eran fundamentales en el tratamiento de las enfermedades, muchas eran escasas. Por ejemplo, la progesterona, que es fundamental para la salud de las mujeres, empezó a estar disponible como medicamento en 1935, pero sus fuentes animales producían cantidades extremadamente pequeñas, lo que limitaba su disponibilidad y aumentaba su costo. Asimismo, en la década de 1940 se empezó a utilizar la cortisona para tratar la artritis y otros trastornos y lesiones, pero su síntesis requirió un proceso de 36 pasos. El químico Percy Lavon Julian recurrió a una fuente más abundante: la soja. Anteriormente, Julian desarrolló un laboratorio para aislar la proteína de la soja, que se utilizaba en la extinción de incendios, entre otras aplicaciones. Se centró en el uso de los esteroles de la soja (sustancias que se utilizan principalmente en las membranas de las plantas) y fue capaz de producir rápidamente progesterona y más tarde testosterona y otras hormonas. Posteriormente desarrolló un proceso para hacer lo mismo con la cortisona y sentó las bases del diseño moderno de fármacos. Dado que la soja y otras fuentes vegetales similares eran extremadamente abundantes, los fármacos pronto estuvieron se masificaron para salvar muchas vidas.
### Química: la ciencia central
La química se conoce a veces como "la ciencia central" debido a su interconexión con una amplia gama de otras disciplinas de Ciencia, Tecnología, Ingeniería y Matemáticas (Science, Technology, Engineering, and Math, STEM). La química y el lenguaje de los químicos desempeñan papeles vitales en la biología, la medicina, la ciencia de los materiales, la ciencia forense, la ciencia ambiental y muchos otros campos (). Los principios básicos de la física son esenciales para entender muchos aspectos de la química, y existe una amplia superposición entre muchas subdisciplinas de ambos campos, como la física química y la química nuclear. Las matemáticas, la informática y la teoría de la información proporcionan importantes herramientas que nos ayudan a calcular, interpretar, describir y, en general, dar sentido al mundo químico. La biología y la química convergen en la bioquímica, que es crucial para comprender los numerosos y complejos factores y procesos que mantienen vivos a los seres vivos (como nosotros). La ingeniería química, la ciencia de los materiales y la nanotecnología combinan los principios químicos y los hallazgos empíricos para producir sustancias útiles, desde la gasolina hasta los tejidos o la electrónica. La agricultura, la ciencia de los alimentos, la veterinaria y la elaboración de cerveza y vino contribuyen a proporcionar el sustento en forma de alimentos y bebidas a la población mundial. La medicina, la farmacología, la biotecnología y la botánica identifican y producen sustancias que nos ayudan a mantenernos sanos. Las ciencias medioambientales, la geología, la oceanografía y las ciencias atmosféricas incorporan muchas ideas químicas para ayudarnos a comprender y proteger mejor nuestro mundo físico. Las ideas químicas se utilizan para ayudar a entender el universo en astronomía y cosmología.
¿Cuáles son algunos de los cambios en la materia que son esenciales para la vida diaria? Digerir y asimilar los alimentos, sintetizar los polímeros que se utilizan para fabricar ropa, envases, utensilios de cocina y tarjetas de crédito y refinar el petróleo crudo para convertirlo en gasolina y otros productos son solo algunos ejemplos. A medida que avance en este curso, descubrirá muchos ejemplos diferentes de cambios en la composición y la estructura de la materia, cómo clasificar estos cambios y cómo se producen, sus causas, los cambios de energía que los acompañan y los principios y las leyes implicados. Mientras aprende sobre estas cosas, estará aprendiendo química, el estudio de la composición, las propiedades y las interacciones de la materia. La práctica de la química no se limita a los libros de química o a los laboratorios: ocurre siempre que alguien se ve envuelto en cambios en la materia o en condiciones que pueden provocar dichos cambios.
### El método científico
La química es una ciencia basada en la observación y la experimentación. Hacer química implica intentar responder preguntas y explicar observaciones en términos de las leyes y teorías de la química, utilizando procedimientos aceptados por la comunidad científica. No existe una única vía para responder una pregunta o explicar una observación, pero hay un aspecto común a todos los enfoques: cada uno de ellos utiliza conocimientos basados en experimentos que se pueden reproducir para verificar los resultados. Algunas rutas implican una hipótesis, que es una explicación tentativa de las observaciones que actúa como guía para reunir y comprobar la información. Una hipótesis se pone a prueba mediante la experimentación, el cálculo o la comparación con los experimentos de otros y, a continuación, se perfecciona según sea necesario.
Algunas hipótesis son intentos de explicar el comportamiento que se resume en leyes. Las leyes de la ciencia resumen un gran número de observaciones experimentales y describen o predicen alguna faceta del mundo natural. Si dicha hipótesis resulta ser capaz de explicar un gran número de datos experimentales, puede alcanzar el estado de teoría. Las teorías científicas son explicaciones bien fundamentadas, completas y comprobables de determinados aspectos de la naturaleza. Las teorías se aceptan porque proporcionan explicaciones satisfactorias, pero se pueden modificar si se dispone de nuevos datos. El camino del descubrimiento que lleva de la pregunta y la observación a la ley o la hipótesis a la teoría, combinado con la verificación experimental de la hipótesis y cualquier modificación necesaria de la teoría, se llama método científico ().
### Los dominios de la química
Los químicos estudian y describen el comportamiento de la materia y la energía en tres dominios diferentes: macroscópico, microscópico y simbólico. Estos dominios proporcionan diferentes formas de considerar y describir el comportamiento químico.
Macro es una palabra griega que significa "grande". El dominio macroscópico nos resulta familiar: es el reino de las cosas cotidianas que son lo suficientemente grandes como para ser percibidas directamente por la vista o el tacto humanos. En la vida cotidiana, esto incluye los alimentos que se comen y la brisa que se siente en la cara. El ámbito macroscópico incluye la química cotidiana y de laboratorio, donde observamos y medimos propiedades físicas y químicas como la densidad, la solubilidad y la inflamabilidad.
Micro viene del griego y significa "pequeño". El dominio microscópico de la química se visita a menudo en la imaginación. Algunos aspectos del dominio microscópico son visibles a través de microscopios ópticos estándar, por ejemplo, muchas células biológicas. Los instrumentos más sofisticados son capaces de obtener imágenes de entidades incluso más pequeñas, como moléculas y átomos (vea la (b)).
Sin embargo, la mayoría de los temas del dominio microscópico de la química son demasiado pequeños para ser vistos incluso con los microscopios más avanzados y solo pueden imaginarse en la mente. Otros componentes del dominio microscópico son los iones y los electrones, los protones y los neutrones y los enlaces químicos, cada uno de los cuales es demasiado pequeño para ser visto.
El dominio simbólico contiene el lenguaje especializado utilizado para representar los componentes de los dominios macroscópico y microscópico. Los símbolos químicos (como los utilizados en la tabla periódica), las fórmulas químicas y las ecuaciones químicas forman parte del dominio simbólico, al igual que los gráficos, los dibujos y los cálculos. Estos símbolos desempeñan un papel importante en la química porque ayudan a interpretar el comportamiento del dominio macroscópico en cuanto a los componentes del dominio microscópico. Uno de los retos para los estudiantes que aprenden química es reconocer que los mismos símbolos pueden representar cosas diferentes en los dominios macroscópico y microscópico, y una de las características que hace que la química sea fascinante es el uso de un dominio que debe imaginarse para explicar el comportamiento en un dominio que puede observarse.
Una forma útil de entender los tres dominios es a través de la sustancia esencial y omnipresente del agua. Que el agua es un líquido a temperaturas moderadas, que se congela para formar un sólido a temperaturas más bajas y que hierve para formar un gas a temperaturas más altas () son observaciones macroscópicas. Pero algunas propiedades del agua caen en el dominio microscópico, es decir, lo que no se puede observar a simple vista. La descripción del agua como compuesta por dos átomos de hidrógeno y un átomo de oxígeno, y la explicación de la congelación y la ebullición en términos de atracciones entre estas moléculas, está dentro del ámbito microscópico. La fórmula H2O, que puede describir el agua a nivel macroscópico o microscópico, es un ejemplo del dominio simbólico. Las abreviaturas (g) para gas, (s) para sólido y (l) para líquido también son simbólicas.
### Conceptos clave y resumen
La química se ocupa de la composición, la estructura y las propiedades de la materia, así como de los modos de interconversión de las distintas formas de materia. Por ello, ocupa un lugar central en el estudio y la práctica de la ciencia y la tecnología. Los químicos utilizan el método científico para realizar experimentos, plantear hipótesis y formular leyes y desarrollar teorías, de modo que puedan comprender mejor el comportamiento del mundo natural. Para ello, operan en los ámbitos macroscópico, microscópico y simbólico. Los químicos miden, analizan, purifican y sintetizan una gran variedad de sustancias importantes para nuestra vida.
### Ejercicios de Química del final del capítulo
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# Ideas esenciales
## Fases y clasificación de la materia
La materia se define como todo lo que ocupa espacio y tiene masa, y está a nuestro alrededor. Los sólidos y los líquidos son más obviamente materia: podemos ver que ocupan espacio y su peso nos indica que tienen masa. Los gases también son materia; si los gases no ocuparan espacio, un globo no se inflaría (aumentaría su volumen) al llenarse de gas.
Sólido, líquido y gaseoso son los tres estados de la materia que se encuentran comúnmente en la tierra (). Un sólido es rígido y posee una forma definida. Un líquido fluye y adopta la forma de su recipiente, salvo que forme una superficie superior plana o ligeramente curvada al actuar sobre ella la gravedad (en gravedad cero, los líquidos adoptan una forma esférica). Tanto las muestras líquidas como las sólidas tienen volúmenes que son casi independientes de la presión. Un gas toma la forma y el volumen de su recipiente.
Un cuarto estado de la materia, el plasma, se da de forma natural en el interior de las estrellas. Un plasma es un estado gaseoso de la materia que contiene un número apreciable de partículas cargadas eléctricamente (). La presencia de estas partículas cargadas confiere propiedades únicas a los plasmas que justifican su clasificación como un estado de la materia distinto de los gases. Además de las estrellas, los plasmas se encuentran en algunos otros ambientes de alta temperatura (tanto naturales como artificiales), como los rayos, ciertas pantallas de televisión e instrumentos analíticos especializados que se utilizan para detectar trazas de metales.
Algunas muestras de materia parecen tener propiedades de sólidos, líquidos o gases al mismo tiempo. Esto puede ocurrir cuando la muestra está compuesta por muchos trozos pequeños. Por ejemplo, podemos verter la arena como si fuera un líquido porque está compuesta por muchos granos pequeños de arena sólida. La materia también puede tener propiedades de más de un estado cuando es una mezcla, como ocurre con las nubes. Las nubes parecen comportarse como gases, pero en realidad son mezclas de aire (gas) y pequeñas partículas de agua (líquida o sólida).
La masa de un objeto es una medida de la cantidad de materia que contiene. Una forma de medir la masa de un objeto es medir la fuerza que se necesita para acelerar el objeto. Se necesita mucha más fuerza para acelerar un automóvil que una bicicleta porque el automóvil tiene mucha más masa. Una forma más común de determinar la masa de un objeto es utilizar una balanza para comparar su masa con una masa estándar.
Aunque el peso está relacionado con la masa, no es lo mismo. El peso se refiere a la fuerza que la gravedad ejerce sobre un objeto. Esta fuerza es directamente proporcional a la masa del objeto. El peso de un objeto cambia cuando cambia la fuerza de gravedad, pero su masa no. La masa de un astronauta no cambia solo porque vaya a la luna. Pero su peso en la luna es solo una sexta parte de su peso en la tierra porque la gravedad de la luna es solo una sexta parte de la de la tierra. Puede sentirse "sin peso" durante su viaje cuando experimenta fuerzas externas insignificantes (gravitacionales o de cualquier otro tipo), aunque, por supuesto, nunca está "sin masa".
La ley de conservación de la materia resume muchas observaciones científicas sobre la materia: afirma que no hay ningún cambio detectable en la cantidad total de materia presente cuando la materia se convierte de un tipo a otro (un cambio químico) o cambia entre los estados sólido, líquido o gaseoso (un cambio físico). La fabricación de cerveza y el funcionamiento de las pilas son ejemplos de la conservación de la materia (). Durante la elaboración de la cerveza, los ingredientes (agua, levadura, cereales, malta, lúpulo y azúcar) se convierten en cerveza (agua, alcohol, carbonatación y sustancias aromáticas) sin que se produzca una pérdida real de sustancia. Esto se ve más claramente durante el proceso de embotellado, cuando la glucosa se convierte en etanol y dióxido de carbono y la masa total de las sustancias no cambia. Esto también puede verse en una batería de plomo y ácido de un automóvil: las sustancias originales (plomo, óxido de plomo y ácido sulfúrico), que son capaces de producir electricidad, se transforman en otras sustancias (sulfato de plomo y agua) que no producen electricidad, sin que cambie la cantidad real de materia.
Aunque esta ley de conservación es válida para todas las conversiones de la materia, los ejemplos convincentes son escasos y poco frecuentes porque, fuera de las condiciones controladas de un laboratorio, rara vez recogemos todo el material que se produce durante una conversión determinada. Por ejemplo, cuando se come, se digiere y se asimila la comida, se conserva toda la materia del alimento original. Pero como una parte de la materia se incorpora al cuerpo y otra parte se excreta en forma de diversos tipos de residuos, es difícil de verificar mediante mediciones.
### Clasificación de la materia
La materia puede clasificarse en varias categorías. Dos grandes categorías son las mezclas y las sustancias puras. Una sustancia pura tiene una composición constante. Todas las muestras de una sustancia pura tienen exactamente la misma composición y propiedades. Cualquier muestra de sacarosa (azúcar de mesa) está compuesta por un 42,1 % de carbono, un 6,5 % de hidrógeno y un 51,4 % de oxígeno en masa. Cualquier muestra de sacarosa tiene también las mismas propiedades físicas, como el punto de fusión, el color y el dulzor, independientemente de la fuente de la que se haya aislado.
Las sustancias puras pueden dividirse en dos clases: elementos y compuestos. Las sustancias puras que no pueden descomponerse en sustancias más simples mediante cambios químicos se denominan elementos. El hierro, la plata, el oro, el aluminio, el azufre, el oxígeno y el cobre son ejemplos comunes de los más de 100 elementos, de los cuales unos 90 se dan de forma natural en la Tierra y unas dos docenas se han creado en laboratorios.
Las sustancias puras, formadas por dos o más elementos, se denominan compuestos. Los compuestos se descomponen mediante cambios químicos para producir elementos u otros compuestos, o ambos. El óxido de mercurio (II), un sólido anaranjado y cristalino, puede descomponerse por el calor en los elementos mercurio y oxígeno (). Cuando se calienta en ausencia de aire, el compuesto sacarosa se descompone en el elemento carbono y el compuesto agua (la fase inicial de este proceso, cuando el azúcar se vuelve marrón, se conoce como caramelización, y es lo que confiere el característico sabor dulce y a nuez a las manzanas caramelizadas, las cebollas caramelizadas y el caramelo). El cloruro de plata(I) es un sólido blanco que puede descomponerse en sus elementos, plata y cloro, por absorción de la luz. Esta propiedad es la base del uso de este compuesto en las películas fotográficas y en los lentes fotocromáticos (aquellos que se oscurecen al exponerse a la luz).
Las propiedades de los elementos combinados son diferentes a las del estado libre o no combinado. Por ejemplo, el azúcar blanco cristalino (sacarosa) es un compuesto resultante de la combinación química del elemento carbono, que es un sólido negro en una de sus formas no combinadas, y los dos elementos hidrógeno y oxígeno, que son gases incoloros cuando no están combinados. El sodio libre, un elemento que es un sólido metálico suave y brillante, y el cloro libre, un elemento que es un gas amarillo-verde, se combinan para formar el cloruro de sodio (sal de mesa), un compuesto que es un sólido blanco y cristalino.
Una mezcla está compuesta por dos o más tipos de materia que pueden estar presentes en cantidades variables y que pueden separarse mediante cambios físicos, como la evaporación (más adelante aprenderá más sobre esto). Una mezcla cuya composición varía de un punto a otro se denomina mezcla heterogénea. El aderezo italiano es un ejemplo de mezcla heterogénea (). Su composición puede variar, ya que puede prepararse con distintas cantidades de aceite, vinagre y hierbas. No es igual de un punto a otro de la mezcla: una gota puede ser mayoritariamente vinagre, mientras que otra gota puede ser mayoritariamente aceite o hierbas porque el aceite y el vinagre se separan y las hierbas se asientan. Otros ejemplos de mezclas heterogéneas son las galletas de chocolate (podemos ver los trozos de chocolate, las nueces y la masa de las galletas por separado) y el granito (podemos ver el cuarzo, la mica, el feldespato, etc.).
Una mezcla homogénea, también llamada solución, presenta una composición uniforme y parece visualmente igual en todo momento. Un ejemplo de solución es una bebida deportiva, que consiste en agua, azúcar, colorante, aromatizante y electrolitos mezclados uniformemente (). Cada gota de una bebida deportiva sabe igual porque cada gota contiene las mismas cantidades de agua, azúcar y otros componentes. Tenga en cuenta que la composición de una bebida deportiva puede variar: puede estar hecha con algo más o menos de azúcar, saborizantes u otros componentes, y seguir siendo una bebida deportiva. Otros ejemplos de mezclas homogéneas son el aire, el sirope de arce, la gasolina y una solución de sal en agua.
Aunque hay poco más de 100 elementos, decenas de millones de compuestos químicos resultan de diferentes combinaciones de estos elementos. Cada compuesto tiene una composición específica y posee propiedades químicas y físicas definidas que lo distinguen de todos los demás compuestos. Y, por supuesto, hay innumerables formas de combinar elementos y compuestos para formar diferentes mezclas. En la se muestra un resumen de cómo distinguir entre las distintas clasificaciones principales de la materia.
El 99 % de la corteza terrestre y la atmósfera están compuestas por, aproximadamente, once elementos (). El oxígeno constituye casi la mitad y el silicio alrededor de la cuarta parte de la cantidad total de estos elementos. La mayoría de los elementos de la Tierra se encuentran en combinaciones químicas con otros elementos; aproximadamente una cuarta parte de los elementos se encuentran también en estado libre.
### Átomos y moléculas
Un átomo es la partícula más pequeña de un elemento que tiene las propiedades de ese elemento y puede entrar en una combinación química. Consideremos el elemento oro, por ejemplo. Imagine que corta una pepita de oro por la mitad, luego corta una de las mitades por la mitad y repite este proceso hasta que queda un trozo de oro tan pequeño que no se puede cortar por la mitad (por muy pequeño que sea su cuchillo). Esta pieza de oro de tamaño mínimo es un átomo (del griego átomos, que significa "indivisible") (). Este átomo dejaría de ser oro si se dividiera más.
La primera sugerencia de que la materia está compuesta por átomos se atribuye a los filósofos griegos Leucipo y Demócrito, que desarrollaron sus ideas en el siglo V a. C. Sin embargo, no fue hasta principios del siglo XIX cuando John Dalton (1766-1844), un maestro de escuela británico muy interesado en la ciencia, apoyó esta hipótesis con mediciones cuantitativas. Desde entonces, repetidos experimentos han confirmado muchos aspectos de esta hipótesis, y se ha convertido en una de las teorías centrales de la química. Otros aspectos de la teoría atómica de Dalton se siguen utilizando, pero con pequeñas revisiones (los detalles de la teoría de Dalton se proporcionan en el capítulo sobre átomos y moléculas).
Un átomo es tan pequeño que su tamaño es difícil de imaginar. Una de las cosas más pequeñas que podemos ver a simple vista es un solo hilo de una tela de araña: Estas hebras tienen un diámetro de aproximadamente 1/10.000 de un centímetro (0,0001 cm). Aunque la sección transversal de una hebra es casi imposible de ver sin un microscopio, es enorme a escala atómica. Un solo átomo de carbono en la red tiene un diámetro de unos 0,000000015 centímetros, y se necesitarían unos 7.000 átomos de carbono para abarcar el diámetro de la hebra. Para ponerlo en perspectiva, si un átomo de carbono tuviera el tamaño de una moneda de diez centavos, la sección transversal de una hebra sería mayor que un campo de fútbol, lo que requeriría unos 150 millones de “monedas de diez centavos" de átomos de carbono para cubrirla. La muestra vistas microscópicas y a nivel atómico cada vez más cercanas de algodón ordinario.
Un átomo es tan ligero que su masa también es difícil de imaginar. Mil millones de átomos de plomo (1.000.000.000 de átomos) pesan aproximadamente 3 10-13 gramos, una masa demasiado ligera para ser pesada incluso en las balanzas más sensibles del mundo. Se necesitarían más de 300.000.000.000.000 de átomos de plomo (300 billones, o 3 1014) para ser pesados, y solo pesarían 0,0000001 gramos.
Es raro encontrar colecciones de átomos individuales. Solo unos pocos elementos, como los gases helio, neón y argón, están formados por un conjunto de átomos individuales que se mueven independientemente unos de otros. Otros elementos, como los gases hidrógeno, nitrógeno, oxígeno y cloro, se componen de unidades formadas por pares de átomos (). Una forma del elemento fósforo consiste en unidades compuestas por cuatro átomos de fósforo. El elemento azufre existe en varias formas, una de las cuales consiste en unidades compuestas por ocho átomos de azufre. Estas unidades se denominan moléculas. Una molécula está formada por dos o más átomos unidos por fuerzas fuertes llamadas enlaces químicos. Los átomos de una molécula se mueven como una unidad, como las latas de refresco de un paquete de seis o un manojo de llaves unidas en un mismo llavero. Una molécula puede estar formada por dos o más átomos idénticos, como las moléculas de los elementos hidrógeno, oxígeno y azufre, o puede estar formada por dos o más átomos diferentes, como las moléculas del agua. Cada molécula de agua es una unidad que contiene dos átomos de hidrógeno y uno de oxígeno. Cada molécula de glucosa es una unidad que contiene 6 átomos de carbono, 12 de hidrógeno y 6 de oxígeno. Al igual que los átomos, las moléculas son increíblemente pequeñas y ligeras. Si un vaso de agua ordinario se ampliara al tamaño de la Tierra, las moléculas de agua de su interior tendrían el tamaño de una pelota de golf.
### Conceptos clave y resumen
La materia es todo lo que ocupa espacio y tiene masa. El bloque básico de la materia es el átomo, la unidad más pequeña de un elemento que puede formar combinaciones con átomos del mismo tipo o con átomos de otros elementos. En muchas sustancias, los átomos se combinan en moléculas. En la Tierra, la materia existe comúnmente en tres estados: sólidos, de forma y volumen fijos; líquidos, de forma variable, pero volumen fijo; y gases, de forma y volumen variables. En condiciones de alta temperatura, la materia también puede existir como plasma. La mayor parte de la materia es una mezcla: Se compone de dos o más tipos de materias que pueden estar presentes en cantidades variables y pueden separarse por medios físicos. Las mezclas heterogéneas varían su composición de un punto a otro; las mezclas homogéneas tienen la misma composición de un punto a otro. Las sustancias puras están formadas por un solo tipo de materia. Una sustancia pura puede ser un elemento, que consta de un solo tipo de átomo y no puede descomponerse mediante un cambio químico, o un compuesto, que consta de dos o más tipos de átomos.
### Ejercicios de química del final del capítulo
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# Ideas esenciales
## Propiedades físicas y químicas
Las características que distinguen una sustancia de otra se llaman propiedades. Una propiedad física es una característica de la materia que no está asociada a un cambio en su composición química. Algunos ejemplos conocidos de propiedades físicas son la densidad, el color, la dureza, los puntos de fusión y ebullición y la conductividad eléctrica. Algunas propiedades físicas, como la densidad y el color, pueden observarse sin cambiar el estado físico de la materia. Otras propiedades físicas, como la temperatura de fusión del hierro o la temperatura de congelación del agua, solo pueden observarse cuando la materia sufre un cambio físico. Un cambio físico es un cambio en el estado o las propiedades de la materia sin que se produzca un cambio en las identidades químicas de las sustancias contenidas en la materia. Los cambios físicos se observan cuando la cera se derrite, cuando el azúcar se disuelve en el café y cuando el vapor se condensa en agua líquida (). Otros ejemplos de cambios físicos son la magnetización y desmagnetización de metales (como se hace con las etiquetas de seguridad antirrobo habituales) y la molienda de sólidos en polvo (que a veces puede producir cambios de color notables). En cada uno de estos ejemplos, hay un cambio en el estado físico, la forma o las propiedades de la sustancia, pero no hay cambio en su composición química.
El cambio de un tipo de materia en otro tipo (o la incapacidad de cambiar) es una propiedad química. Algunos ejemplos de propiedades químicas son la inflamabilidad, la toxicidad, la acidez y muchos otros tipos de reactividad. El hierro, por ejemplo, se combina con el oxígeno en presencia del agua para formar óxido; el cromo no se oxida (). La nitroglicerina es muy peligrosa porque explota con facilidad; el neón no representa casi ningún peligro porque es muy poco reactivo.
Un cambio químico siempre produce uno o más tipos de materia que difieren de la materia presente antes del cambio. La formación de óxido es un cambio químico porque el óxido es un tipo de materia diferente del hierro, el oxígeno y el agua presentes antes de que se formara el óxido. La explosión de la nitroglicerina es un cambio químico porque los gases producidos son tipos de materia muy diferentes de la sustancia original. Otros ejemplos de cambios químicos son las reacciones que se llevan a cabo en un laboratorio (como la reacción del cobre con el ácido nítrico), todas las formas de combustión (quema) y la cocción, digestión o putrefacción de los alimentos ().
Las propiedades de la materia se dividen en dos categorías. Si la propiedad depende de la cantidad de materia presente, es una propiedad extensiva. La masa y el volumen de una sustancia son ejemplos de propiedades extensivas; por ejemplo, un galón de leche tiene una masa mayor que un vaso de leche. El valor de una propiedad extensiva es directamente proporcional a la cantidad de materia en cuestión. Si la propiedad de una muestra de materia no depende de la cantidad de materia presente, es una propiedad intensiva. La temperatura es un ejemplo de propiedad intensiva. Si el galón y la taza de leche están cada uno a 20 °C (temperatura ambiente), cuando se combinan, la temperatura sigue siendo de 20 °C. Como otro ejemplo, considere las propiedades distintas, pero relacionadas del calor y la temperatura. Una gota de aceite de cocina caliente salpicada en el brazo provoca una breve y leve molestia, mientras que una olla de aceite caliente produce graves quemaduras. Tanto la gota como la olla de aceite están a la misma temperatura (propiedad intensiva), pero la olla contiene claramente mucho más calor (propiedad extensiva).
Aunque muchos elementos difieren drásticamente en sus propiedades químicas y físicas, algunos elementos tienen propiedades similares. Por ejemplo, muchos elementos conducen bien el calor y la electricidad, mientras que otros son conductores deficientes. Estas propiedades pueden utilizarse para clasificar los elementos en tres clases: metales (elementos que conducen bien), no metales (elementos que conducen de forma deficiente) y metaloides (elementos que tienen conductividades intermedias).
La tabla periódica es una tabla que agrupa los elementos con propiedades similares (). Aprenderá más sobre la tabla periódica a medida que continúe su estudio de la química.
### Conceptos clave y resumen
Todas las sustancias tienen propiedades físicas y químicas distintas, y pueden sufrir cambios físicos o químicos. Las propiedades físicas, como la dureza y el punto de ebullición, y los cambios físicos, como la fusión o la congelación, no implican un cambio en la composición de la materia. Las propiedades químicas, como la inflamabilidad y la acidez, y los cambios químicos, como la oxidación, implican la producción de una materia diferente a la presente.
Las propiedades medibles pertenecen a una de las dos categorías. Las propiedades extensivas dependen de la cantidad de materia presente, por ejemplo, la masa del oro. Las propiedades intensivas no dependen de la cantidad de materia presente, por ejemplo, la densidad del oro. El calor es un ejemplo de propiedad extensiva, y la temperatura es un ejemplo de propiedad intensiva.
### Ejercicios de Química del final del capítulo
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# Ideas esenciales
## Mediciones
Las mediciones proporcionan gran parte de la información que sirve de base a las hipótesis, teorías y leyes que describen el comportamiento de la materia y la energía en los dominios macroscópico y microscópico de la química. Toda medición proporciona tres tipos de información: el tamaño o la magnitud de la medición (un número); un patrón de comparación para la medición (una unidad); y una indicación de la incertidumbre de la medición. Mientras que el número y la unidad se representan explícitamente cuando se escribe una cantidad, la incertidumbre es un aspecto del resultado de la medición que se representa más implícitamente y que se tratará más adelante.
El número de la medida puede representarse de diferentes maneras, incluida la forma decimal y la notación científica. (La notación científica también se conoce como notación exponencial; en el Apéndice B se puede encontrar una revisión de este tema). Por ejemplo, el peso máximo de despegue de un avión Boeing 777-200ER es de 298.000 kilogramos, lo que también puede escribirse como 2,98 105 kg. La masa del mosquito medio es de unos 0,0000025 kilogramos, lo que puede escribirse como 2,5 10-6 kg.
Las unidades, como los litros, las libras y los centímetros, son estándares de comparación para las mediciones. Una botella de 2 litros de un refresco contiene un volumen de bebida que es el doble del volumen aceptado de 1 litro. La carne con la que se prepara una hamburguesa de 0,25 libras pesa una cuarta parte de lo que se acepta como peso de 1 libra. Sin unidades, un número puede carecer de sentido, ser confuso o poner en peligro la vida. Supongamos que un médico prescribe fenobarbital para controlar las convulsiones de un paciente y establece una dosis de "100" sin especificar las unidades. Esto no solo será confuso para el profesional médico que administra la dosis, sino que las consecuencias pueden ser fatales: 100 mg administrados tres veces al día pueden ser eficaces como anticonvulsivos, pero una sola dosis de 100 g es más de 10 veces la cantidad letal.
En la se enumeran las unidades de medida de siete propiedades fundamentales ("unidades base"). Los estándares de estas unidades se fijan por acuerdo internacional y se denominan como el Sistema Internacional de Unidades o Unidades SI (del francés, “Le Système International d'Unités”). El Instituto Nacional de Normas y Tecnología (National Institute of Standards and Technology, NIST) de los Estados Unidos utiliza las unidades del SI desde 1964. Las unidades para otras propiedades pueden derivarse de estas siete unidades base.
Las unidades de medida cotidianas suelen definirse como fracciones o múltiplos de otras unidades. La leche se suele envasar en recipientes de 1 galón (4 cuartos), 1 cuarto (0,25 galones) y una pinta (0,5 cuartos). Este mismo enfoque se utiliza con las unidades del SI, pero estas fracciones o múltiplos son siempre potencias de 10. Las unidades fraccionarias o múltiples del SI se nombran utilizando un prefijo y el nombre de la unidad base. Por ejemplo, una longitud de 1.000 metros también se llama kilómetro porque el prefijo kilo significa "mil", que en notación científica es 103 (1 kilómetro = 1.000 m = 103 m). Los prefijos utilizados y las potencias a las que se elevan 10 se encuentran en la .
### Unidades básicas del SI
Las unidades iniciales del sistema métrico, que acabaron evolucionando hacia el sistema SI, se establecieron en Francia durante la Revolución Francesa. Los estándares originales del metro y el kilogramo fueron adoptados allí en 1799 y, con el tiempo, por otros países. En esta sección se presentan cuatro de las unidades básicas del SI utilizadas habitualmente en química. En capítulos posteriores se introducirán otras unidades del SI.
### Longitud
La unidad estándar de longitud, tanto en el sistema SI como en el sistema métrico original, es el metro (m). Un metro se especificó originalmente como 1/10.000.000 de la distancia del Polo Norte al ecuador. Ahora se define como la distancia que recorre la luz en el vacío en 1/299.792.458 de segundo. Un metro es aproximadamente 3 pulgadas más largo que una yarda (); un metro es aproximadamente 39,37 pulgadas o 1,094 yardas. Las distancias más largas suelen indicarse en kilómetros (1 km = 1.000 m = 103 m), mientras que las más cortas pueden indicarse en centímetros (1 cm = 0,01 m = 10–2 m) o en milímetros (1 mm = 0,001 m = 10–3 m).
### Masa
La unidad estándar de masa en el sistema SI es el kilogramo (kg). El kilogramo fue definido anteriormente por la Unión Internacional de Química Pura y Aplicada (IUPAC) como la masa de un objeto de referencia específico. Este objeto era originalmente un litro de agua pura, y más recientemente era un cilindro de metal hecho de una aleación de platino-iridio con una altura y un diámetro de 39 mm (). En mayo de 2019, esta definición se cambió por otra que se basa en valores medidos con precisión de varias constantes físicas fundamentalesPara conocer más detalles, consulte https://www.nist.gov/pml/weights-and-measures/si-units-mass. Un kilo es aproximadamente 2,2 libras. El gramo (g) es exactamente igual a 1/1.000 de la masa del kilogramo (10–3 kg).
### Temperatura
La temperatura es una propiedad intensiva. La unidad de temperatura del SI es el kelvin (K). La convención de la IUPAC es utilizar kelvin (todo en minúsculas) para la palabra, K (en mayúsculas) para el símbolo de la unidad, y no usar ni la palabra "grado" ni el símbolo de grado (°). El grado Celsius (°C) también está permitido en el sistema SI, utilizándose tanto la palabra "grado" como el símbolo de grado para las mediciones Celsius. Los grados Celsius tienen la misma magnitud que los kelvin, pero las dos escalas colocan sus ceros en lugares diferentes. El agua se congela a 273,15 K (0 °C) y hierve a 373,15 K (100 °C) por definición, y la temperatura normal del cuerpo humano es de aproximadamente 310 K (37 °C). La conversión entre estas dos unidades y la escala Fahrenheit se tratará más adelante en este capítulo.
### Tiempo
La unidad básica de tiempo del SI es el segundo (s). Los intervalos de tiempo pequeños y grandes pueden expresarse con los prefijos adecuados; por ejemplo, 3 microsegundos = 0,000003 s = 3 10-6 y 5 megasegundos = 5.000.000 s = 5 106 s. También se pueden utilizar horas, días y años.
### Unidades derivadas del SI
Podemos derivar muchas unidades a partir de las siete unidades básicas del SI. Por ejemplo, podemos utilizar la unidad base de longitud para definir una unidad de volumen, y las unidades base de masa y longitud para definir una unidad de densidad.
### Volumen
El volumen es la medida de la cantidad de espacio que ocupa un objeto. La unidad de volumen estándar del SI está definida por la unidad base de longitud (). El volumen estándar es un metro cúbico (m, un cubo con una longitud de arista de exactamente un metro. Para dispensar un metro cúbico de agua, podríamos construir una caja cúbica con longitudes de borde de exactamente un metro. Esta caja contendría un metro cúbico de agua o cualquier otra sustancia.
Una unidad de volumen más utilizada se deriva del decímetro (0,1 m, o 10 cm). Un cubo con longitudes de aristas de exactamente un decímetro contiene un volumen de un decímetro cúbico (dm3). Un litro (L) es el nombre más común para el decímetro cúbico. Un litro es aproximadamente 1,06 cuartos de galón.
Un centímetro cúbico (cm es el volumen de un cubo con una longitud de arista de exactamente un centímetro. La abreviatura cc (de centímetro cúbico) es utilizada a menudo por los profesionales de la salud. Un centímetro cúbico equivale a un mililitro (mL) y es 1/1.000 de un litro.
### Densidad
Utilizamos la masa y el volumen de una sustancia para determinar su densidad. Por lo tanto, las unidades de densidad se definen por las unidades base de masa y longitud.
La densidad de una sustancia es la relación entre la masa de una muestra de la sustancia y su volumen. La unidad del SI para la densidad es el kilogramo por metro cúbico (kg/m3). Sin embargo, para muchas situaciones, esta es una unidad inconveniente, y a menudo utilizamos gramos por centímetro cúbico (g/cm3) para las densidades de sólidos y líquidos, y gramos por litro (g/L) para los gases. Aunque hay excepciones, la mayoría de los líquidos y sólidos tienen densidades que oscilan entre unos 0,7 g/cm3 (la densidad de la gasolina) y 19 g/cm3 (la densidad del oro). La densidad del aire es de aproximadamente 1,2 g/L. La muestra las densidades de algunas sustancias comunes.
Aunque hay muchas formas de determinar la densidad de un objeto, quizá el método más sencillo consista en hallar por separado la masa y el volumen del objeto, y luego dividir la masa de la muestra entre su volumen. En el siguiente ejemplo, la masa se halla directamente mediante el pesaje, pero el volumen se halla indirectamente mediante las mediciones de la longitud.
### Conceptos clave y resumen
Las mediciones proporcionan información cuantitativa que es fundamental en el estudio y la práctica de la química. Cada medida tiene una cantidad, una unidad de comparación y una incertidumbre. Las medidas pueden representarse en notación decimal o científica. Los científicos utilizan principalmente unidades del SI (Sistema Internacional), como los metros, los segundos y los kilogramos, así como unidades derivadas, como los litros (para el volumen) y los g/cm3 (para la densidad). En muchos casos, es conveniente utilizar prefijos que den lugar a unidades fraccionarias y múltiples, como microsegundos (10-6 segundos) y megahercios (106 hercios), respectivamente.
### Ecuaciones clave
### Ejercicios de Química del final del capítulo
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# Ideas esenciales
## Incertidumbre, exactitud y precisión de las mediciones
El conteo es el único tipo de medición que está libre de incertidumbre, siempre que el número de objetos contados no cambie mientras se realiza el proceso de conteo. El resultado de esta medición de conteo es un ejemplo de número exacto. Al contar los huevos de un cartón, se puede determinar exactamente cuántos huevos contiene el cartón. Los números de las cantidades definidas también son exactos. Por definición, 1 pie es exactamente 12 pulgadas, 1 pulgada es exactamente 2,54 centímetros y 1 gramo es exactamente 0,001 kilogramos. Sin embargo, las cantidades derivadas de mediciones distintas del conteo son inciertas en mayor o menor medida debido a las limitaciones prácticas del proceso de medición utilizado.
### Cifras significativas en la medición
Los números de las cantidades medidas, a diferencia de las cantidades definidas o contadas directamente, no son exactos. Para medir el volumen de un líquido en una probeta graduada, debe hacer una lectura en el fondo del menisco, el punto más bajo de la superficie curva del líquido.
Consulte la ilustración en la . El fondo del menisco en este caso se encuentra claramente entre las marcas 21 y 22, lo que significa que el volumen de líquido es ciertamente mayor de 21 mL, pero menor de 22 mL. El menisco parece estar un poco más cerca de la marca de 22 mL que de la de 21 mL, por lo que una estimación razonable del volumen del líquido sería de 21,6 mL. En el número 21,6, por tanto, los dígitos 2 y 1 son ciertos, pero el 6 es una estimación. Algunas personas podrían estimar que la posición del menisco está igualmente distante de cada una de las marcas y estimar el dígito de la décima posición como 5, mientras que otras podrían pensar que está aún más cerca de la marca de 22 mL y estimar este dígito como 7. Tenga en cuenta que sería inútil intentar estimar un dígito para la centésima, dado que el dígito de la décima es incierto. En general, las escalas numéricas como la de este cilindro graduado permitirán realizar mediciones hasta la décima parte de la división más pequeña de la escala. La escala en este caso tiene divisiones de 1 mL, por lo que los volúmenes pueden medirse con una precisión de 0,1 mL.
Este concepto es válido para todas las mediciones, incluso si no se hace una estimación de forma activa. Si coloca una moneda de 25 centavos en una balanza electrónica estándar, puede obtener una lectura de 6,72 g. Las cifras 6 y 7 son ciertas, y el 2 indica que la masa de la moneda de 25 centavos está probablemente entre 6,71 y 6,73 gramos. La moneda de 25 centavos pesa aproximadamente 6,72 gramos, con una incertidumbre nominal en la medición de ± 0,01 gramos. Si la moneda se pesa en una balanza más sensible, la masa podría ser de 6,723 g. Esto significa que su masa está entre 6,722 y 6,724 gramos, lo que supone una incertidumbre de 0,001 gramos. Toda medición tiene cierta incertidumbre, que depende del dispositivo utilizado (y de la habilidad del usuario). Todos los dígitos de una medida, incluido el último dígito incierto, se denominan cifras significativas o dígitos significativos. Tenga en cuenta que el cero puede ser un valor medido; por ejemplo, si se sube a una balanza que muestra el peso a la libra más cercana y muestra "120", entonces el 1 (centenas), el 2 (decenas) y el 0 (unidades) son todos valores significativos (medidos).
Un resultado de medición se comunica correctamente cuando sus dígitos significativos representan con precisión la certeza del proceso de medición. Pero ¿qué pasaría si se analizara un valor notificado y se intentara determinar qué es significativo y qué no? Bueno, para empezar, todos los dígitos que no son ceros son significativos, y los ceros son los únicos que requieren alguna reflexión. Utilizaremos los términos "inicial", “último" y "cautivo" para los ceros y estudiaremos cómo tratarlos.
Empezando por el primer dígito distinto de cero a la izquierda, cuente este dígito y todos los dígitos restantes a la derecha. Es el número de cifras significativas de la medida, a menos que el último dígito sea un cero a la izquierda del punto decimal.
Los ceros cautivos son el resultado de la medición y, por tanto, siempre son significativos. Los ceros a la izquierda, sin embargo, nunca son significativos; simplemente nos indican dónde se encuentra el punto decimal.
Los ceros a la izquierda en este ejemplo no son significativos. Podríamos utilizar la notación exponencial (como se describe en el Apéndice B) y expresar el número como 8,32407 10-3; entonces el número 8,32407 contiene todas las cifras significativas, y 10-3 ubica el punto decimal.
El número de cifras significativas es incierto en un número que termina con un cero a la izquierda de la ubicación del punto decimal. Los ceros de la medida 1.300 gramos podrían ser significativos o simplemente indicar dónde se encuentra el punto decimal. La ambigüedad puede resolverse con el uso de la notación exponencial: 1,3 103 (dos cifras significativas), 1,30 103 (tres cifras significativas, si se miden las decenas), o 1.300 103 (cuatro cifras significativas, si también se midió el lugar de las unidades). En los casos en los que solo se dispone del número con formato decimal, es prudente asumir que todos los últimos ceros no son significativos.
Al determinar las cifras significativas, asegúrese de prestar atención a los valores comunicados y piense en la medición y las cifras significativas en términos de lo que es razonable o probable al evaluar si el valor tiene sentido. Por ejemplo, el censo oficial de enero de 2014 informó de que la población residente en los EE. UU. era de 317.297.725 personas. ¿Cree usted que la población de los EE. UU. se determinó correctamente con las nueve cifras significativas indicadas, es decir, con el número exacto de personas? Constantemente las personas nacen, mueren o se trasladan al país o fuera de él, y se hacen suposiciones para tener en cuenta el gran número de personas que no se contabilizan realmente. Debido a estas incertidumbres, podría ser más razonable esperar que conozcamos la población con una aproximación de un millón de personas, en cuyo caso la población debería indicarse como 3,17 108 personas.
### Cifras significativas en los cálculos
Un segundo principio importante de la incertidumbre es que los resultados calculados a partir de una medición son al menos tan inciertos como la propia medición. Hay que tener en cuenta la incertidumbre de las mediciones para no tergiversarla en los resultados calculados. Una forma de hacerlo es informar del resultado de un cálculo con el número correcto de cifras significativas, que está determinado por las siguientes tres reglas de redondeo de números:
1. Al sumar o restar números, redondee el resultado al mismo número de decimales que el número con menos decimales (el valor menos seguro en términos de suma y resta).
2. Al multiplicar o dividir números, redondee el resultado al mismo número de cifras que el número con el menor número de cifras significativas (el menor valor seguro en términos de multiplicación y división).
3. Si el dígito que hay que descartar (el que está inmediatamente a la derecha del dígito que hay que retener) es inferior a 5, "se redondea hacia abajo" y se mantiene el dígito sin modificar; si es superior a 5, "se redondea hacia arriba" y se incrementa el dígito retenido en 1. Si el dígito eliminado es 5, y es el último dígito del número o está seguido solo por ceros, redondee hacia arriba o hacia abajo, lo que dé un valor par para el dígito retenido. Si algún dígito distinto de cero sigue al 5 descartado, redondee hacia arriba. (La última parte de esta regla puede parecerle un poco extraña, pero se basa en estadísticas fiables y tiene por objeto evitar cualquier sesgo al descartar el dígito "5", ya que se acerca por igual a los dos valores posibles del dígito retenido).
Los siguientes ejemplos ilustran la aplicación de esta regla en el redondeo de algunos números diferentes a tres cifras significativas:
1. 0,028675 se redondea a 0,0287 (el dígito descartado, 7, es mayor que 5)
2. 18,3384 se redondea "hacia abajo" a 18,3 (el dígito descartado, 3, es menor que 5)
3. 6,8752 redondea "hacia arriba" a 6,88 (el dígito descartado es 5, y le sigue un dígito distinto de cero)
4. 92,85 redondea "hacia abajo" a 92,8 (el dígito descartado es 5, y el dígito retenido es par)
Repasemos estas reglas con algunos ejemplos.
En medio de todos estos tecnicismos, es importante tener en cuenta la razón de ser de estas reglas sobre las cifras significativas y el redondeo: representar correctamente la certeza de los valores comunicados y garantizar que un resultado calculado no se represente como más seguro que el valor menos seguro utilizado en el cálculo.
### Precisión y exactitud
Los científicos suelen realizar mediciones repetidas de una cantidad para garantizar la calidad de sus hallazgos y evaluar tanto la precisión como la exactitud de sus resultados. Se dice que las mediciones son precisas si dan resultados muy similares cuando se repiten de la misma manera. Se considera que una medición es exacta si da un resultado muy cercano al valor verdadero o aceptado. Los valores precisos coinciden entre sí; los valores exactos coinciden con un valor verdadero. Estas caracterizaciones pueden extenderse a otros contextos, como los resultados de una competición de tiro con arco ().
Supongamos que a una química de control de calidad de una empresa farmacéutica se le encarga la comprobación de la exactitud y la precisión de tres máquinas diferentes que deben dispensar 10 onzas (296 mL) de sirope para la tos en frascos de almacenamiento. Procede a utilizar cada máquina para llenar cinco botellas y luego determina cuidadosamente el volumen real dispensado, obteniendo los resultados tabulados en la .
Teniendo en cuenta estos resultados, informará de que el dispensador N.º 1 es preciso (los valores son todos cercanos entre sí, con una diferencia de unas pocas décimas de mililitro) pero no es exacto (ninguno de los valores se acerca al valor objetivo de 296 mL, siendo cada uno de ellos más de 10 mL demasiado bajo). Los resultados del dispensador N.º 2 representan una mayor exactitud (cada volumen está a menos de 3 mL de 296 mL) pero una peor precisión (los volúmenes varían en más de 4 mL). Por último, puede informar que el dispensador N.º 3 funciona bien, dispensando el sirope para la tos con precisión (todos los volúmenes están a 0,1 mL del volumen objetivo) y con exactitud (los volúmenes difieren entre sí en no más de 0,2 mL).
### Conceptos clave y resumen
Las cantidades pueden definirse o medirse. Las cantidades medidas tienen una incertidumbre asociada que está representada por el número de cifras significativas del número de la cantidad. La incertidumbre de una cantidad calculada depende de las incertidumbres de las cantidades utilizadas en el cálculo y se refleja en el redondeo del valor. Las cantidades se caracterizan con respecto a la exactitud (proximidad a un valor verdadero o aceptado) y la precisión (variación entre los resultados de las mediciones repetidas).
### Ejercicios de Química del final del capítulo
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# Ideas esenciales
## Tratamiento matemático de los resultados de las mediciones
A menudo ocurre que una cantidad de interés puede no ser fácil (ni incluso posible) de medir directamente, sino que debe calcularse a partir de otras propiedades medidas directamente y de relaciones matemáticas adecuadas. Por ejemplo, considere la posibilidad de medir la rapidez media de un atleta que corre “sprints”. Esto se consigue normalmente midiendo el tiempo que necesita el atleta para correr desde la línea de salida hasta la línea de meta, y la distancia entre estas dos líneas, y luego calculando la velocidad a partir de la ecuación que relaciona estas tres propiedades:
Un velocista de calidad olímpica puede correr 100 m en aproximadamente 10 s, lo que corresponde a una rapidez media de
Observe que esta simple aritmética consiste en dividir los números de cada cantidad medida para obtener el número de la cantidad calculada (100/10 = 10) y, del mismo modo, dividir las unidades de cada cantidad medida para obtener la unidad de la cantidad calculada (m/s = m/s). Ahora, considere la posibilidad de utilizar esta misma relación para predecir el tiempo que necesita una persona que corre a esta velocidad, para poder recorrer una distancia de 25 m. Se utiliza la misma relación entre las tres propiedades, pero en este caso, las dos cantidades proporcionadas son una velocidad (10 m/s) y una distancia (25 m). Para obtener la propiedad buscada, el tiempo, hay que reordenar la ecuación de forma adecuada:
El tiempo se puede calcular entonces como
Una vez más, la aritmética de los números (25/10 = 2,5) se acompañó de la misma aritmética de las unidades (m/m/s = s) para producir el número y la unidad del resultado, 2,5 s. Tenga en cuenta que, al igual que en el caso de los números, cuando una unidad se divide entre otra idéntica (en este caso, m/m), el resultado es "1" o, como se suele decir, las unidades se "cancelan".
Estos cálculos son ejemplos de un enfoque matemático versátil conocido como análisis dimensional (o método de factores de conversión). El análisis dimensional se basa en esta premisa: las unidades de las cantidades deben someterse a las mismas operaciones matemáticas que sus números asociados. Este método puede aplicarse a cálculos que van desde simples conversiones de unidades hasta cálculos más complejos de varios pasos que implican varias cantidades diferentes.
### Factores de conversión y análisis dimensional
Una relación de dos cantidades equivalentes expresadas con diferentes unidades de medida puede utilizarse como factor de conversión de unidades. Por ejemplo, las longitudes de 2,54 cm y 1 pulgada son equivalentes (por definición), por lo que se puede derivar un factor de conversión de unidades a partir de la relación,
En la figuran otros factores de conversión que se utilizan comúnmente.
Cuando una cantidad (como la distancia en pulgadas) se multiplica por un factor de conversión de unidades adecuado, la cantidad se convierte en un valor equivalente con unidades diferentes (como la distancia en centímetros). Por ejemplo, el salto vertical de un jugador de baloncesto de 34 pulgadas se puede convertir a centímetros mediante:
Dado que esta simple aritmética implica cantidades, la premisa del análisis dimensional requiere que multipliquemos tanto los números como las unidades. Los números de estas dos cantidades se multiplican para obtener el número de la cantidad del producto, 86, mientras que las unidades se multiplican para obtener . Al igual que en el caso de los números, una relación de unidades idénticas también es numéricamente igual a uno, y el producto unitario se simplifica así a cm. (Cuando las unidades son idénticas se dividen para dar un factor de 1, entonces se dice que se "cancelan"). El análisis dimensional puede utilizarse para confirmar la aplicación correcta de los factores de conversión de unidades, como se demuestra en el siguiente ejemplo.
Más allá de las simples conversiones de unidades, el método de factores de conversión puede utilizarse para resolver problemas más complejos que impliquen cálculos. Independientemente de los detalles, el enfoque básico es el mismo: todos los factores que intervienen en el cálculo deben orientarse adecuadamente para garantizar que sus etiquetas (unidades) se anulen o combinen adecuadamente para dar la unidad deseada en el resultado. A medida que se avanza en el estudio de la química, se encontrarán muchas oportunidades para aplicar este enfoque.
### Conversión de unidades de temperatura
Utilizamos la palabra temperatura para referirnos al calor o al frío de una sustancia. Una forma de medir un cambio de temperatura es utilizar el hecho de que la mayoría de las sustancias se expanden cuando su temperatura aumenta y se contraen cuando su temperatura disminuye. El líquido de un termómetro de vidrio común cambia su volumen a medida que cambia la temperatura, y la posición de la superficie del líquido atrapado a lo largo de una escala impresa puede utilizarse como medida de la temperatura.
Las escalas de temperatura se definen en relación con las temperaturas de referencia seleccionadas: Dos de los más utilizados son las temperaturas de congelación y ebullición del agua a una presión atmosférica determinada. En la escala Celsius, 0 °C se define como la temperatura de congelación del agua y 100 °C como la temperatura de ebullición del agua. El espacio entre las dos temperaturas se divide en 100 intervalos iguales, que llamamos grados. En la escala Fahrenheit, el punto de congelación del agua se define como 32 °F y la temperatura de ebullición como 212 °F. El espacio entre estos dos puntos en un termómetro Fahrenheit se divide en 180 partes iguales (grados).
La definición de las escalas de temperatura Celsius y Fahrenheit, tal y como se ha descrito en el párrafo anterior, da lugar a una relación ligeramente más compleja entre los valores de temperatura en estas dos escalas que para las diferentes unidades de medida de otras propiedades. La mayoría de las unidades de medida de una propiedad determinada son directamente proporcionales entre sí (y = mx). Utilizando las unidades de longitud conocidas como un ejemplo:
donde y = longitud en pies, x = longitud en pulgadas, y la constante de proporcionalidad, m, es el factor de conversión. Sin embargo, las escalas de temperatura Celsius y Fahrenheit no comparten un punto cero común, por lo que la relación entre estas dos escalas es lineal y no proporcional (y = mx + b). En consecuencia, la conversión de una temperatura de una de estas escalas a la otra requiere algo más que la simple multiplicación por un factor de conversión, m, también se debe tener en cuenta las diferencias en los puntos cero de las escalas (b).
La ecuación lineal que relaciona las temperaturas Celsius y Fahrenheit se deriva fácilmente de las dos temperaturas utilizadas para definir cada escala. Al representar la temperatura en grados Celsius como x y la temperatura en grados Fahrenheit como y, se calcula que la pendiente, m, es:
La intersección en y de la ecuación, b, se calcula entonces utilizando cualquiera de los pares de temperaturas equivalentes, (100 °C, 212 °F) o (0 °C, 32 °F), como:
La ecuación que relaciona las escalas de temperatura (T) es entonces:
Una forma abreviada de esta ecuación que omite las unidades de medida es:
Al reordenar esta ecuación se obtiene la forma útil para convertir de Fahrenheit a Celsius:
Como se ha mencionado anteriormente en este capítulo, la unidad del SI de temperatura es el kelvin (K). A diferencia de las escalas Celsius y Fahrenheit, la escala kelvin es una escala de temperatura absoluta en la que el 0 (cero) K corresponde a la temperatura más baja que teóricamente se puede alcanzar. Dado que la escala de temperatura kelvin es absoluta, no se incluye el símbolo del grado en la abreviatura de la unidad, K. El descubrimiento a principios del siglo XIX de la relación entre el volumen de un gas y la temperatura sugirió que el volumen de un gas sería cero a -273,15 °C. En 1848, el físico británico William Thompson, que más tarde adoptó el título de Lord Kelvin, propuso una escala de temperatura absoluta basada en este concepto (en el capítulo de este texto dedicado a los gases se trata con más detalle este tema).
La temperatura de congelación del agua en esta escala es de 273,15 K y su temperatura de ebullición es de 373,15 K. Observe que la diferencia numérica de estas dos temperaturas de referencia es de 100, la misma que para la escala Celsius, por lo que la relación lineal entre estas dos escalas de temperatura presentará una pendiente de . Con el mismo enfoque, se deducen que las ecuaciones para convertir entre las escalas de temperatura kelvin y Celsius son:
El 273,15 de estas ecuaciones se ha determinado experimentalmente, por lo que no es exacto. La muestra la relación entre las tres escalas de temperatura.
Aunque la escala de temperatura kelvin (absoluta) es la escala oficial de temperatura del SI, la escala Celsius se utiliza habitualmente en muchos contextos científicos y es la escala elegida para contextos no científicos en casi todo el mundo. Muy pocos países (los Estados Unidos y sus territorios, las Bahamas, Belice, las Islas Caimán y Palau) siguen utilizando la temperatura Fahrenheit para el clima, la medicina y la cocina.
### Conceptos clave y resumen
Las mediciones se realizan utilizando diversas unidades. A menudo es útil o necesario convertir una cantidad medida de una unidad a otra. Estas conversiones se llevan a cabo mediante factores de conversión de unidades, que se obtienen mediante aplicaciones sencillas de un enfoque matemático denominado método de factores de conversión o análisis dimensional. Esta estrategia también se emplea para calcular las cantidades buscadas utilizando las cantidades medidas y las relaciones matemáticas adecuadas.
### Ecuaciones clave
### Ejercicios de Química del final del capítulo
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# Átomos, moléculas e iones
## Introducción
Las afecciones pulmonares y el cáncer de pulmón se encuentran entre las enfermedades más devastadoras del mundo, en parte debido a la detección y el diagnóstico tardíos. La mayoría de los procedimientos de detección no invasivos no son fiables, y los pacientes suelen resistirse a los métodos más precisos debido a la incomodidad de los procedimientos o al peligro potencial que estos conllevan. Sin embargo, ¿qué pasaría si se pudiera diagnosticar con precisión mediante una simple prueba de aliento?
La detección precoz de biomarcadores, sustancias que indican la enfermedad o el estado fisiológico de un organismo, podría permitir el diagnóstico y el tratamiento antes de que una afección se vuelva grave o irreversible. Estudios recientes han demostrado que el aliento exhalado puede contener moléculas que pueden ser biomarcadores de una exposición reciente a contaminantes ambientales o de patologías que van desde el asma hasta el cáncer de pulmón. Los científicos están trabajando en el desarrollo de "huellas" de biomarcadores que podrían utilizarse para diagnosticar una enfermedad específica basándose en las cantidades e identidades de ciertas moléculas del aliento exhalado por un paciente. En el laboratorio de Sangeeta Bhatia en el MIT, un equipo utilizó sustancias que reaccionan específicamente en el interior del tejido pulmonar enfermo; los productos de las reacciones estarán presentes como biomarcadores que pueden identificarse mediante espectrometría de masas (un método analítico que se comenta más adelante en el capítulo). Una posible aplicación permitiría a los pacientes con síntomas tempranos inhalar o ingerir una sustancia "sensor" y, minutos después, respirar en un detector para el diagnóstico. Investigaciones similares realizadas por científicos como Laura López-Sánchez ofrecen procesos similares para el cáncer de pulmón. Un concepto esencial que subyace a este objetivo es el de la identidad de una molécula, que viene determinada por el número y los tipos de átomos que contiene, y por cómo están unidos entre sí. En este capítulo se describen algunos de los principios químicos fundamentales relacionados con la composición de la materia, incluidos los fundamentales para el concepto de identidad molecular. |
# Átomos, moléculas e iones
## Las primeras ideas de la teoría atómica
La primera discusión registrada sobre la estructura básica de la materia proviene de los antiguos filósofos griegos, los científicos de su época. En el siglo V a.C., Leucipo y Demócrito sostenían que toda la materia estaba compuesta por partículas pequeñas y finitas que llamaban átomos, término derivado de la palabra griega "indivisible". Pensaron en los átomos como partículas móviles que diferían en forma y tamaño, y que podían unirse. Más tarde, Aristóteles y otros llegaron a la conclusión de que la materia estaba formada por diversas combinaciones de los cuatro “elementos”: fuego, tierra, aire y agua, y podía dividirse infinitamente. Curiosamente, estos filósofos pensaban en los átomos y los "elementos" como conceptos filosóficos, pero aparentemente nunca se plantearon realizar experimentos para comprobar sus ideas.
La visión aristotélica de la composición de la materia se mantuvo durante más de dos mil años, hasta que el maestro de escuela inglés John Dalton contribuyó a revolucionar la química con su hipótesis de que el comportamiento de la materia podía explicarse mediante una teoría atómica. Publicada por primera vez en 1807, muchas de las hipótesis de Dalton sobre las características microscópicas de la materia siguen siendo válidas en la teoría atómica moderna. Estos son los postulados de la teoría atómica de Dalton.
1. La materia está compuesta por partículas extremadamente pequeñas llamadas átomos. Un átomo es la unidad más pequeña de un elemento que puede participar en un cambio químico.
2. Un elemento está formado por un solo tipo de átomo, que tiene una masa característica del elemento y que es la misma para todos los átomos de ese elemento (). Una muestra macroscópica de un elemento contiene un número increíblemente grande de átomos, todos los cuales tienen propiedades químicas idénticas.
3. Los átomos de un elemento difieren en propiedades de los átomos de todos los demás elementos.
4. Un compuesto está formado por átomos de dos o más elementos combinados en una pequeña proporción de números enteros. En un determinado compuesto, el número de átomos de cada uno de sus elementos está siempre presente en la misma proporción ().
5. Los átomos no se crean ni se destruyen durante un cambio químico, sino que se reordenan para dar lugar a sustancias diferentes de las presentes antes del cambio ().
La teoría atómica de Dalton ofrece una explicación microscópica de las numerosas propiedades macroscópicas de la materia de las que ha aprendido. Por ejemplo, si un elemento como el cobre está formado por un solo tipo de átomos, no puede descomponerse en sustancias más simples, es decir, en sustancias compuestas por menos tipos de átomos. Y si los átomos no se crean ni se destruyen durante un cambio químico, entonces la masa total de materia presente cuando la materia cambia de un tipo a otro permanecerá constante (ley de conservación de la materia).
Dalton conocía los experimentos del químico francés Joseph Proust, quien demostró que todas las muestras de un compuesto puro contienen los mismos elementos en la misma proporción en masa. Esta afirmación se conoce como la ley de las proporciones definidas o la ley de la composición constante. La sugerencia de que el número de átomos de los elementos de un determinado compuesto existe siempre en la misma proporción es coherente con estas observaciones. Por ejemplo, cuando se analizan diferentes muestras de isooctano (un componente de la gasolina y uno de los estándares utilizados en el sistema de octanaje), se encuentra que tienen una proporción de masa de carbono a hidrógeno de 5,33:1, como se muestra en la .
Cabe destacar que, aunque todas las muestras de un determinado compuesto tengan la misma relación de masas, lo contrario no es cierto en general. Es decir, las muestras que tienen la misma relación de masa no son necesariamente la misma sustancia. Por ejemplo, hay muchos compuestos, además del isooctano, que también tienen una relación de masas de carbono a hidrógeno de 5,33:1,00.
Dalton también utilizó los datos de Proust, así como los resultados de sus propios experimentos, para formular otra ley interesante. La ley de las proporciones múltiples establece que cuando dos elementos reaccionan para formar más de un compuesto, una masa fija de un elemento reaccionará con masas del otro elemento en una relación de números enteros y sencillos. Por ejemplo, el cobre y el cloro pueden formar un sólido verde y cristalino con una relación de masas de 0,558 g de cloro por 1 g de cobre, así como un sólido cristalino marrón con una relación de masas de 1,116 g de cloro por 1 g de cobre. Estas relaciones por sí mismas pueden no parecer especialmente interesantes o informativas; sin embargo, si tomamos una relación de estas proporciones obtenemos un resultado útil y posiblemente sorprendente: una relación de números enteros y sencillos.
Esta relación de 2 a 1 significa que el compuesto marrón tiene el doble de cantidad de cloro por cantidad de cobre que el compuesto verde.
Esto puede explicarse mediante la teoría atómica si la relación cobre-cloro en el compuesto marrón es de 1 átomo de cobre por 2 átomos de cloro, y la relación en el compuesto verde es de 1 átomo de cobre por 1 átomo de cloro. La relación de los átomos de cloro (y, por lo tanto, la relación de sus masas) es por consiguiente de 2 a 1 ().
### Conceptos clave y resumen
Los antiguos griegos propusieron que la materia está formada por partículas extremadamente pequeñas llamadas átomos. Dalton postuló que cada elemento tiene un tipo de átomo característico que difiere en sus propiedades de los átomos de todos los demás elementos, y que los átomos de diferentes elementos pueden combinarse en proporciones fijas, sencillas y enteras para formar compuestos. Las muestras de un determinado compuesto tienen todas las mismas proporciones elementales en masa. Cuando dos elementos forman compuestos diferentes, una masa determinada de un elemento se combina con masas del otro elemento en una relación de números enteros sencilla. Durante cualquier cambio químico, los átomos no se crean ni se destruyen.
### Ejercicios de Química del final del capítulo
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# Átomos, moléculas e iones
## Evolución de la teoría atómica
Si la materia está compuesta de átomos, ¿de qué están compuestos los átomos? ¿Son las partículas más pequeñas o hay algo más pequeño? A finales del siglo XIX, varios científicos interesados en cuestiones como estas investigaron las descargas eléctricas que podían producirse en los gases a baja presión, siendo el descubrimiento más importante el realizado por el físico inglés J. J. Thomson con un tubo de rayos catódicos. Este aparato consistía en un tubo de vidrio sellado al que se le había quitado casi todo el aire; el tubo contenía dos electrodos metálicos. Cuando se aplicaba un alto voltaje a través de los electrodos, aparecía entre ellos un rayo visible llamado rayo catódico. Este haz se desviaba hacia la carga positiva y se alejaba de la carga negativa, y se producía de la misma manera con idénticas propiedades cuando se utilizaban diferentes metales para los electrodos. En experimentos similares, el rayo fue desviado simultáneamente por un campo magnético aplicado, y las mediciones de la extensión de la desviación y la intensidad del campo magnético permitieron a Thomson calcular la relación carga-masa de las partículas del rayo catódico. Los resultados de estas mediciones indicaron que estas partículas eran mucho más ligeras que los átomos ().
Basándose en sus observaciones, esto es lo que propuso Thomson y por qué: Las partículas son atraídas por cargas positivas (+) y repelidas por cargas negativas (-), por lo que deben estar cargadas negativamente (las cargas similares se repelen y las cargas diferentes se atraen); son menos masivos que los átomos y no se distinguen, independientemente del material de origen, por lo que deben ser componentes fundamentales y subatómicos de todos los átomos. Aunque controvertida en su momento, la idea de Thomson fue aceptada gradualmente, y su partícula de rayos catódicos es lo que ahora llamamos electrón, una partícula subatómica con carga negativa y una masa más de mil veces inferior a la de un átomo. El término "electrón" fue acuñado en 1891 por el físico irlandés George Stoney, a partir de "ion eléctrico“.
En 1909, el físico estadounidense Robert A. Millikan descubrió más información sobre el electrón gracias a sus experimentos con "gotas de aceite". Millikan creó gotas de aceite microscópicas, que podían cargarse eléctricamente por fricción mientras se formaban o utilizando rayos X. Estas gotas caen inicialmente por gravedad, pero su avance hacia abajo puede ser frenado o incluso invertido por un campo eléctrico situado en la parte inferior del aparato. Al ajustar la intensidad del campo eléctrico y realizar cuidadosas mediciones y cálculos adecuados, Millikan pudo determinar la carga de las gotas individuales ().
Observando los datos de carga que recogió Millikan, se habrá reconocido que la carga de una gota de aceite es siempre un múltiplo de una carga específica, 1,6 10-19 C. Millikan llegó a la conclusión de que este valor debe ser, por tanto, una carga fundamental (la carga de un solo electrón) y que sus cargas medidas se deben a un exceso de un electrón (1 por 1,6 10-19 C), dos electrones (2 por 1,6 10-19 C), tres electrones (3 por 1,6 10-19 C), y así sucesivamente, en una determinada gota de aceite. Dado que la carga de un electrón ya se conocía gracias a las investigaciones de Millikan, y la relación carga/masa ya se conocía gracias a las investigaciones de Thomson (1759 1011 C/kg), solo hacía falta un simple cálculo para determinar también la masa del electrón.
Para ese momento, los científicos habían establecido que el átomo no era indivisible, como creía Dalton, y gracias al trabajo de Thomson, Millikan y otros, se conocía la carga y la masa de las partículas subatómicas negativas, los electrones. Sin embargo, la parte de carga positiva de un átomo aún no se comprendía bien. En 1904, Thomson propuso el modelo del "pudín de pasas" de los átomos, que describía una masa cargada positivamente con una cantidad igual de carga negativa en forma de electrones incrustados en ella, ya que todos los átomos son eléctricamente neutros. En 1903, Hantaro Nagaoka propuso un modelo que le hacía competencia y era un átomo similar a Saturno, compuesto por una esfera con carga positiva rodeada de un halo de electrones ().
El siguiente gran avance en la comprensión del átomo vino de la mano de Ernest Rutherford, un físico neozelandés que desarrolló gran parte de su carrera científica en Canadá e Inglaterra. Realizó una serie de experimentos utilizando un haz de partículas alfa (partículas α) de alta velocidad y carga positiva que se producían por el decaimiento radiactivo del radio; las partículas α están formadas por dos protones y dos neutrones (aprenderá más sobre el decaimiento radiactivo en el capítulo sobre química nuclear). Rutherford y sus colegas Hans Geiger (más tarde famoso por el contador Geiger) y Ernest Marsden dirigieron un haz de partículas α, cuya fuente estaba incrustada en un bloque de plomo para absorber la mayor parte de la radiación, a una pieza muy fina de lámina de oro y examinaron la dispersión resultante de las partículas α utilizando una pantalla luminiscente que brillaba brevemente cuando era golpeada por una partícula α.
¿Qué descubrieron? La mayoría de las partículas atravesaron la lámina sin ser desviadas en absoluto. Sin embargo, algunas se desviaron ligeramente, y un número muy pequeño se desvió casi directamente hacia la fuente (). Rutherford describió el hallazgo de estos resultados: "Fue el acontecimiento más increíble que me ha ocurrido en mi vida. Era casi tan increíble como si disparara un proyectil de 15 pulgadas a un trozo de papel de seda y este volviera y lo golpeara”.Ernest Rutherford, "The Development of the Theory of Atomic Structure" ("El desarrollo de la teoría de la estructura atómica"), ed. J. A. Ratcliffe, en
Esto es lo que Rutherford dedujo: dado que la mayoría de las partículas α de movimiento rápido atravesaron los átomos de oro sin desviarse, deben haber viajado a través de un espacio esencialmente vacío dentro del átomo. Las partículas alfa están cargadas positivamente, por lo que las desviaciones surgieron cuando se encontraron con otra carga positiva (las cargas similares se repelen). Como las cargas similares se repelen, las pocas partículas α con carga positiva que cambiaron bruscamente de trayectoria debieron chocar, o acercarse, a otro cuerpo que también tenía una carga positiva muy concentrada. Debido a que las desviaciones se produjeron una pequeña fracción de tiempo, esta carga solo ocupó una pequeña cantidad del espacio en la lámina de oro. Analizando detalladamente una serie de estos experimentos, Rutherford llegó a dos conclusiones:
1. El volumen ocupado por un átomo debe consistir en una gran cantidad de espacio vacío.
2. En el centro de cada átomo debe haber un cuerpo pequeño, relativamente pesado y con carga positiva, el núcleo.
Este análisis llevó a Rutherford a proponer un modelo en el que un átomo consiste en un núcleo muy pequeño, cargado positivamente, en el que se concentra la mayor parte de la masa del átomo, rodeado por los electrones cargados negativamente, de modo que el átomo es eléctricamente neutro (). Después de muchos más experimentos, Rutherford también descubrió que los núcleos de otros elementos contienen el núcleo de hidrógeno como un "bloque de construcción", y llamó a esta partícula más fundamental el protón, la partícula subatómica de carga positiva que se encuentra en el núcleo. Este modelo nuclear del átomo, propuesto hace más de un siglo, se sigue utilizando hoy en día, con un pequeño añadido que aprenderá a continuación.
Otro hallazgo importante fue el descubrimiento de los isótopos. A principios del siglo XX, los científicos identificaron varias sustancias que parecían ser nuevos elementos, aislándolas de minerales radiactivos. Por ejemplo, un "nuevo elemento" producido por el decaimiento radiactivo del torio recibió inicialmente el nombre de mesotorio. Sin embargo, un análisis más detallado demostró que el mesotorio era químicamente idéntico al radio (otro producto de decaimiento), a pesar de tener una masa atómica diferente. Este resultado, junto con hallazgos similares para otros elementos, llevó al químico inglés Frederick Soddy a darse cuenta de que un elemento podía tener tipos de átomos con masas diferentes que eran químicamente idénticos. Estos diferentes tipos se denominan isótopos, es decir, átomos del mismo elemento que difieren en masa. Soddy recibió el Premio Nobel de Química en 1921 por este descubrimiento.
Aún quedaba un enigma: Se sabía que el núcleo contenía casi toda la masa de un átomo, y que el número de protones solo aportaba la mitad, o menos, de esa masa. Se hicieron diferentes propuestas para explicar lo que constituía la masa restante, incluida la existencia de partículas neutras en el núcleo. Como es de esperar, detectar partículas sin carga es un gran reto, y no fue hasta 1932 cuando James Chadwick encontró pruebas de la existencia de neutrones, partículas subatómicas sin carga con una masa aproximadamente igual a la de los protones. La existencia del neutrón también explica los isótopos: Difieren en masa porque tienen diferente número de neutrones, pero son químicamente idénticos porque tienen el mismo número de protones. Esto se explicará con más detalle más adelante en este capítulo.
### Conceptos clave y resumen
Aunque nadie ha visto realmente el interior de un átomo, los experimentos han demostrado mucho sobre la estructura atómica. El tubo de rayos catódicos de Thomson demostró que los átomos contienen pequeñas partículas con carga negativa llamadas electrones. Millikan descubrió que existe una carga eléctrica fundamental: la carga de un electrón. El experimento de la lámina de oro de Rutherford demostró que los átomos tienen un núcleo pequeño, denso y con carga positiva; las partículas con carga positiva dentro del núcleo se llaman protones. Chadwick descubrió que el núcleo también contiene partículas neutras llamadas neutrones. Soddy demostró que los átomos de un mismo elemento pueden diferir en masa, lo que se denomina isótopos.
### Ejercicios de Química del final del capítulo
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# Átomos, moléculas e iones
## Estructura atómica y simbolismo
El desarrollo de la teoría atómica moderna reveló mucho sobre la estructura interna de los átomos. Se aprendió que un átomo contiene un núcleo muy pequeño compuesto por protones con carga positiva y neutrones sin carga, rodeado por un volumen de espacio mucho mayor que contiene electrones con carga negativa. El núcleo contiene la mayor parte de la masa de un átomo porque los protones y los neutrones son mucho más pesados que los electrones, mientras que estos ocupan casi todo el volumen del átomo. El diámetro de un átomo es del orden de 10-10 m, mientras que el diámetro del núcleo es de aproximadamente 10-15 m, aproximadamente unas 100,000 veces menor. Para tener una perspectiva sobre sus tamaños relativos, tome en cuenta esto: si el núcleo fuera del tamaño de un arándano, el átomo tendría el tamaño de un estadio de fútbol ().
Los átomos, y los protones, neutrones y electrones que los componen, son extremadamente pequeños. Por ejemplo, un átomo de carbono pesa menos de 2 10-23 g, y un electrón tiene una carga inferior a 2 10-19 (culombio). Al describir las propiedades de objetos diminutos como los átomos, utilizamos unidades de medida adecuadamente pequeñas, como la unidad de masa atómica (uma o su equivalente u) y la unidad de carga fundamental (e). La u se definió originalmente en función del hidrógeno, el elemento más ligero, y posteriormente en función del oxígeno. Desde 1961, se define con respecto al isótopo más abundante del carbono, cuyos átomos tienen asignadas masas de exactamente 12 u. (Este isótopo se conoce como "carbono-12", como se verá más adelante en este módulo). Por lo tanto, una u es exactamente de la masa de un átomo de carbono-12: 1 u = 1,6605 10-24 g. (El Dalton (Da) y la unidad de masa atómica unificada (u) son unidades alternativas equivalentes a la uma). La unidad fundamental de carga (también llamada carga elemental) es igual a la magnitud de la carga de un electrón (e) donde e = 1,602 10-19 C.
Un protón tiene una masa de 1,0073 u y una carga de 1+. Un neutrón es una partícula ligeramente más pesada con una masa de 1,0087 u y una carga de cero; como su nombre indica, es neutral. El electrón tiene una carga de 1, y es una partícula mucho más ligera con una masa de aproximadamente 0,00055 u (se necesitarían unos 1800 electrones para igualar la masa de un protón). Las propiedades de estas partículas fundamentales se resumen en la . (Un estudiante observador podría notar que la suma de las partículas subatómicas de un átomo no es igual a la masa real del átomo: la masa total de seis protones, seis neutrones y seis electrones es de 12,0993 u, ligeramente mayor que 12,00 u. Esta masa "ausente" se conoce como defecto de masa, y lo aprenderá en el capítulo de química nuclear).
El número de protones en el núcleo de un átomo es su número atómico (Z). Es el rasgo que define a un elemento: Su valor determina la identidad del átomo. Por ejemplo, cualquier átomo que contenga seis protones es el elemento carbono y tiene el número atómico 6, independientemente del número de neutrones o electrones que pueda tener. Un átomo neutro debe contener el mismo número de cargas positivas y negativas, por lo que el número de protones es igual al número de electrones. Por lo tanto, el número atómico también indica el número de electrones de un átomo. El número total de protones y neutrones de un átomo se denomina número de masa (A). El número de neutrones es, por tanto, la diferencia entre el número de masa y el número atómico: A – Z = número de neutrones.
Los átomos son eléctricamente neutros si contienen el mismo número de protones con carga positiva y de electrones con carga negativa. Cuando los números de estas partículas subatómicas no son iguales, el átomo está cargado eléctricamente y se llama ion. La carga de un átomo se define de la siguiente forma:
Carga atómica = número de protones − número de electrones
Como se verá con más detalle más adelante en este capítulo, los átomos (y las moléculas) suelen adquirir carga al ganar o perder electrones. Un átomo que gana uno o más electrones mostrará una carga negativa y se llama anión. Los átomos con carga positiva, llamados cationes, se forman cuando un átomo pierde uno o más electrones. Por ejemplo, un átomo de sodio neutro (Z = 11) tiene 11 electrones. Si este átomo pierde un electrón, se convertirá en un catión con carga 1+ (11 - 10 = 1+). Un átomo de oxígeno neutro (Z = 8) tiene ocho electrones, y si gana dos electrones se convertirá en un anión con carga 2 (8 - 10 = 2-).
### Símbolos químicos
Un símbolo químico es una abreviatura que utilizamos para indicar un elemento o un átomo de un elemento. Por ejemplo, el símbolo del mercurio es Hg (). Utilizamos el mismo símbolo para indicar un átomo de mercurio (en un dominio microscópico) o para marcar un contenedor de muchos átomos del elemento mercurio (en un dominio macroscópico).
Los símbolos de varios elementos comunes y de sus átomos se muestran en la . Algunos símbolos se derivan del nombre común del elemento; otros son abreviaturas del nombre en otro idioma. La mayoría de los símbolos tienen una o dos letras, pero se han utilizado símbolos de tres letras para describir algunos elementos que tienen números atómicos superiores a 112. Para evitar confusiones con otras notaciones, solo se escribe en mayúsculas la primera letra de un símbolo. Por ejemplo, Co es el símbolo del elemento cobalto, pero CO es la notación del compuesto monóxido de carbono, que contiene átomos de los elementos carbono (C) y oxígeno (O). Todos los elementos conocidos y sus símbolos se encuentran en la tabla periódica en la (que también se encuentra en el Apéndice A).
Tradicionalmente, el descubridor (o los descubridores) de un nuevo elemento le da el nombre. Sin embargo, hasta que el nombre sea reconocido por la Unión Internacional de Química Pura y Aplicada (IUPAC), el nombre recomendado del nuevo elemento se basa en las palabras latinas de su número atómico. Por ejemplo, el elemento 106 se llamó unnilhexium (Unh), el elemento 107 se llamó unnilseptium (Uns) y el elemento 108 se llamó unniloctium (Uno) durante varios años. Estos elementos reciben ahora el nombre de los científicos (u ocasionalmente de los lugares), por ejemplo, el elemento 106 se conoce ahora como seaborgio (Sg) en honor a Glenn Seaborg, un premio Nobel que participó en el descubrimiento de varios elementos pesados. El elemento 109 recibió su nombre en honor a Lise Meitner, que descubrió la fisión nuclear, un fenómeno que tendría repercusiones en todo el mundo. Meitner también contribuyó al descubrimiento de algunos isótopos importantes, que se comentan a continuación.
### Isótopos
El símbolo de un isótopo específico de cualquier elemento se escribe colocando el número de masa como superíndice a la izquierda del símbolo del elemento (). El número atómico se escribe a veces como un subíndice que precede al símbolo, pero como este número define la identidad del elemento, al igual que su símbolo, a menudo se omite. Por ejemplo, el magnesio existe como una mezcla de tres isótopos, cada uno con un número atómico de 12 y con números de masa de 24, 25 y 26, respectivamente. Estos isótopos pueden identificarse como 24Mg, 25Mg, y 26Mg. Estos símbolos de isótopos se leen como "elemento, número de masa" y se pueden simbolizar de acuerdo con esta lectura. Por ejemplo, 24Mg se lee como "magnesio 24", y puede escribirse como "magnesio-24" o "Mg-24" 25Mg se lee como "magnesio 25", y puede escribirse como "magnesio-25" o "Mg-25" Todos los átomos de magnesio tienen 12 protones en su núcleo. Solo se diferencian porque un átomo de 24Mg tiene 12 neutrones en su núcleo, un átomo de 25Mg tiene 13 neutrones y un 26Mg tiene 14 neutrones.
La información sobre los isótopos naturales de los elementos con números atómicos del 1 al 10 se encuentra en la . Observe que, además de los nombres y símbolos estándar, los isótopos del hidrógeno suelen denominarse con nombres comunes y los símbolos que los acompañan. El hidrógeno-2, simbolizado como 2H, también se llama deuterio y a veces se simboliza como D. El hidrógeno-3, simbolizado como 3H, también se llama tritio y a veces se simboliza como T.
### Masa atómica
Dado que cada protón y cada neutrón contribuyen aproximadamente con una u a la masa de un átomo, y cada electrón contribuye con mucho menos, la masa atómica de un solo átomo es aproximadamente igual a su número de masa (un número entero). Sin embargo, las masas medias de los átomos de la mayoría de los elementos no son números enteros porque la mayoría de los elementos existen de forma natural como mezclas de dos o más isótopos.
La masa de un elemento que aparece en una tabla periódica o en una tabla de masas atómicas es una masa promedio ponderada de todos los isótopos presentes en una muestra natural de ese elemento. Es igual a la suma de la masa de cada isótopo individual multiplicada por su abundancia fraccionada.
Por ejemplo, el elemento boro está compuesto por dos isótopos: Alrededor del 19,9 % de todos los átomos de boro son 10B con una masa de 10,0129 u, y el 80,1 % restante son 11B con una masa de 11,0093 u. Se calcula que la masa atómica promedio del boro es:
Es importante entender que ningún átomo de boro pesa exactamente 10,8 u; 10,8 u es la masa media de todos los átomos de boro, y los átomos de boro individuales pesan aproximadamente 10 u o también 11 u.
También podemos hacer variaciones de este tipo de cálculo, como se muestra en el siguiente ejemplo.
Como podrá descubrir, los isótopos son importantes en la naturaleza y, sobre todo, en la comprensión humana de la ciencia y la medicina. Consideremos un solo isótopo natural y estable: el oxígeno-18, que aparece en la tabla anterior, es uno de los isótopos ambientales. Es importante en paleoclimatología, por ejemplo, porque los científicos pueden utilizar la relación entre el oxígeno-18 y el oxígeno-16 en un núcleo de hielo para determinar la temperatura de las precipitaciones a lo largo del tiempo. El oxígeno-18 también fue fundamental para descubrir las vías metabólicas y los mecanismos de las enzimas. Mildred Cohn fue pionera en el uso de estos isótopos para que actuaran como trazadores, de modo que los investigadores pudieran seguir su trayectoria a través de las reacciones y comprender mejor lo que ocurre. Uno de sus primeros descubrimientos permitió conocer la fosforilación de la glucosa que tiene lugar en las mitocondrias. Además, los métodos de utilización de los isótopos para esta investigación contribuyeron a campos de estudio enteros.
La presencia y la abundancia natural de los isótopos pueden determinarse experimentalmente mediante un instrumento llamado espectrómetro de masas. La espectrometría de masas (EM) se utiliza ampliamente en química, medicina forense, ciencias medioambientales y muchos otros campos para analizar y ayudar a identificar las sustancias de una muestra de material. En un espectrómetro de masas típico (), la muestra se vaporiza y se expone a un haz de electrones de alta energía que hace que los átomos (o moléculas) de la muestra se carguen eléctricamente, normalmente perdiendo uno o más electrones. A continuación, estos cationes atraviesan un campo eléctrico o magnético (variable) que desvía la trayectoria de cada catión en una medida que depende tanto de su masa como de su carga (de forma similar a como se desvía la trayectoria de una gran bola de acero que rueda junto a un imán en menor medida que la de una pequeña bola de acero). Los iones se detectan y se realiza un gráfico del número relativo de iones generados frente a sus relaciones masa/carga (un espectro de masas). La altura de cada característica vertical o pico en un espectro de masas es proporcional a la fracción de cationes con la relación masa/carga especificada. Desde su uso inicial durante el desarrollo de la teoría atómica moderna, la EM ha evolucionado hasta convertirse en una potente herramienta de análisis químico en una amplia gama de aplicaciones.
### Conceptos clave y resumen
Un átomo está formado por un pequeño núcleo con carga positiva rodeado de electrones. El núcleo contiene protones y neutrones; su diámetro es aproximadamente unas 100.000 veces menor que el del átomo. La masa de un átomo suele expresarse en unidades de masa atómica (u), lo que se denomina masa atómica. Una u se define exactamente como de la masa de un átomo de carbono-12 y es igual a 1,6605 10-24 g.
Los protones son partículas relativamente pesadas con una carga de 1+ y una masa de 1,0073 u. Los neutrones son partículas relativamente pesadas, sin carga y con una masa de 1,0087 u. Los electrones son partículas ligeras con una carga de 1 y una masa de 0,00055 u. El número de protones en el núcleo se llama número atómico (Z) y es la propiedad que define la identidad elemental de un átomo. La suma de los números de protones y neutrones del núcleo se denomina número de masa y, expresado en u, es aproximadamente igual a la masa del átomo. Un átomo es neutro cuando contiene igual número de electrones y protones.
Los isótopos de un elemento son átomos con el mismo número atómico, pero diferente número de masa; los isótopos de un elemento, por lo tanto, difieren entre sí solo en el número de neutrones dentro del núcleo. Cuando un elemento natural está compuesto por varios isótopos, la masa atómica del elemento representa el promedio de las masas de los isótopos implicados. Un símbolo químico identifica los átomos de una sustancia mediante símbolos, que son abreviaturas de una, dos o tres letras para los átomos.
### Ecuaciones clave
### Ejercicios de Química del final del capítulo
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# Átomos, moléculas e iones
## Fórmulas químicas
Una fórmula molecular es una representación de una molécula que utiliza símbolos químicos para indicar los tipos de átomos seguidos de subíndices para mostrar el número de átomos de cada tipo en la molécula. (Solo se utiliza un subíndice cuando hay más de un átomo de un tipo determinado). Las fórmulas moleculares también se utilizan como abreviaturas de los nombres de los compuestos.
La fórmula estructural de un compuesto proporciona la misma información que su fórmula molecular (los tipos y números de átomos de la molécula), pero también muestra cómo están conectados los átomos en la molécula. La fórmula estructural del metano contiene símbolos para un átomo de C y cuatro átomos de H, indicando el número de átomos de la molécula (). Las líneas representan los enlaces que mantienen unidos los átomos. (Un enlace químico es una atracción entre átomos o iones que los mantiene unidos en una molécula o un cristal). Más adelante hablaremos de los enlaces químicos y veremos cómo predecir la disposición de los átomos en una molécula. Por ahora, basta con saber que las líneas son una indicación de cómo están conectados los átomos en una molécula. Un modelo de barras y esferas muestra la disposición geométrica de los átomos con tamaños atómicos no a escala, y un modelo de espacio lleno muestra los tamaños relativos de los átomos.
Aunque muchos elementos están formados por átomos individuales, algunos existen como moléculas formadas por dos o más átomos del elemento unidos químicamente. Por ejemplo, la mayoría de las muestras de los elementos hidrógeno, oxígeno y nitrógeno están compuestas por moléculas que contienen dos átomos cada una (llamadas moléculas diatómicas) y, por tanto, tienen las fórmulas moleculares H2, O2, y N2, respectivamente. Otros elementos que suelen encontrarse como moléculas diatómicas son el flúor (F2), cloro (Cl2), bromo (Br2), y el yodo (I2). La forma más común del elemento azufre está compuesta por moléculas que constan de ocho átomos de azufre; su fórmula molecular es S8 ().
Es importante tener en cuenta que un subíndice a continuación de un símbolo y un número delante de un símbolo no representan lo mismo; por ejemplo, H2 y 2H representan especies claramente diferentes. H2 es una fórmula molecular; representa una molécula diatómica de hidrógeno, formada por dos átomos del elemento que están químicamente enlazados. La expresión 2H, en cambio, indica dos átomos de hidrógeno separados que no están combinados como una unidad. La expresión 2H2 representa dos moléculas de hidrógeno diatómico ().
Los compuestos se forman cuando dos o más elementos se combinan químicamente, dando lugar a la formación de enlaces. Por ejemplo, el hidrógeno y el oxígeno pueden reaccionar para formar agua, y el sodio y el cloro pueden reaccionar para formar sal de mesa. A veces describimos la composición de estos compuestos con una fórmula empírica, que indica los tipos de átomos presentes y la relación numérica más sencilla del número de átomos (o iones) del compuesto. Por ejemplo, el dióxido de titanio (utilizado como pigmento en la pintura blanca y en los protectores solares de tipo blanco y espeso) tiene una fórmula empírica de TiO2. Esto identifica los elementos titanio (Ti) y oxígeno (O) como constituyentes del dióxido de titanio, e indica la presencia del doble de átomos del elemento oxígeno que de átomos del elemento titanio ().
Como se ha comentado anteriormente, podemos describir un compuesto con una fórmula molecular, en la que los subíndices indican el número real de átomos de cada elemento en una molécula del compuesto. En muchos casos, la fórmula molecular de una sustancia se deriva de la determinación experimental tanto de su fórmula empírica como de su masa molecular (la suma de las masas atómicas de todos los átomos que componen la molécula). Por ejemplo, se puede determinar experimentalmente que el benceno contiene dos elementos, carbono (C) e hidrógeno (H), y que por cada átomo de carbono en el benceno hay un átomo de hidrógeno. Así, la fórmula empírica es CH. Una determinación experimental de la masa molecular revela que una molécula de benceno contiene seis átomos de carbono y seis de hidrógeno, por lo que la fórmula molecular del benceno es C6H6 ().
Si conocemos la fórmula de un compuesto, podemos determinar fácilmente la fórmula empírica. (Este es un ejercicio un tanto académico; en la práctica se suele seguir la cronología inversa). Por ejemplo, la fórmula molecular del ácido acético, el componente que da al vinagre su sabor fuerte, es C2H4O2. Esta fórmula indica que una molécula de ácido acético () contiene dos átomos de carbono, cuatro de hidrógeno y dos de oxígeno. La relación de átomos es de 2:4:2. Al dividir entre el mínimo común denominador (2) se obtiene la relación más sencilla de números enteros de átomos, 1:2:1, por lo que la fórmula empírica es CH2O. Tome en cuenta que una fórmula molecular es siempre un múltiplo entero de una fórmula empírica.
Es importante tener en cuenta que es posible que los mismos átomos estén dispuestos de diferentes maneras: Los compuestos con la misma fórmula molecular pueden tener diferentes enlaces entre átomos y, por tanto, diferentes estructuras. Por ejemplo, ¿podría haber otro compuesto con la misma fórmula que el ácido acético, C2H4O2? Y si es así, ¿cuál sería la estructura de sus moléculas?
Si predice que podría existir otro compuesto con la fórmula C2H4O2, entonces ha demostrado una buena perspicacia química y está en lo cierto. Dos átomos de C, cuatro átomos de H y dos átomos de O también pueden disponerse para formar un formiato de metilo, que se utiliza en la fabricación, como insecticida y para acabados de secado rápido. Las moléculas de formiato de metilo tienen uno de los átomos de oxígeno entre los dos átomos de carbono, lo que difiere de la disposición de las moléculas de ácido acético. El ácido acético y el formiato de metilo son ejemplos de isómeros, es decir, compuestos con la misma fórmula química, pero con estructuras moleculares diferentes (). Observe que esta pequeña diferencia en la disposición de los átomos tiene un efecto importante en sus respectivas propiedades químicas. Desde luego, no querrá utilizar una solución de formiato de metilo como sustituto de una solución de ácido acético (vinagre) cuando prepare un aliño para la ensalada.
Existen muchos tipos de isómeros (). El ácido acético y el formiato de metilo son isómeros estructurales, compuestos en los que las moléculas difieren en la forma en que los átomos están conectados entre sí. También hay varios tipos de isómeros espaciales, en los que las orientaciones relativas de los átomos en el espacio pueden ser diferentes. Por ejemplo, el compuesto carvona (que se encuentra en las semillas de alcaravea, la menta verde y las cáscaras de mandarina) consta de dos isómeros que son imágenes especulares entre sí. La S-(+)-carvona huele a alcaravea, y la R-(-)-carvona huele a menta verde.
### Conceptos clave y resumen
Una fórmula molecular utiliza símbolos químicos y subíndices para indicar el número exacto de los diferentes átomos de una molécula o compuesto. Una fórmula empírica da la relación más simple de números enteros de átomos en un compuesto. Una fórmula estructural indica la disposición de los enlaces de los átomos en la molécula. Los modelos de barras y esferas y de espacio lleno muestran la disposición geométrica de los átomos en una molécula. Los isómeros son compuestos con la misma fórmula molecular, pero con distinta disposición de los átomos.
### Ejercicios de Química del final del capítulo
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# Átomos, moléculas e iones
## La tabla periódica
A medida que los primeros químicos trabajaban en la purificación de los minerales y descubrían más elementos, se dieron cuenta de que varios elementos podían agruparse por sus comportamientos químicos similares. Una de estas agrupaciones incluye el litio (Li), el sodio (Na) y el potasio (K): Todos estos elementos son brillantes, conducen bien el calor y la electricidad y tienen propiedades químicas similares. Una segunda agrupación incluye el calcio (Ca), el estroncio (Sr) y el bario (Ba), que también son brillantes, buenos conductores del calor y la electricidad, y tienen propiedades químicas en común. Sin embargo, las propiedades específicas de estas dos agrupaciones son notablemente diferentes entre sí. Por ejemplo: El Li, el Na y el K son mucho más reactivos que el Ca, el Sr y el Ba; el Li, el Na y el K forman compuestos con el oxígeno en una relación de dos de sus átomos por uno de oxígeno, mientras que el Ca, el Sr y el Ba forman compuestos con uno de sus átomos por uno de oxígeno. El flúor (F), el cloro (Cl), el bromo (Br) y el yodo (I) también presentan propiedades similares entre sí, pero estas propiedades son drásticamente diferentes a las de cualquiera de los elementos anteriores.
Dimitri Mendeleev en Rusia (1869) y Lothar Meyer en Alemania (1870) reconocieron de forma independiente que existía una relación periódica entre las propiedades de los elementos conocidos en aquella época. Ambos publicaron tablas con los elementos ordenados según el aumento de la masa atómica. Pero Mendeleev fue un paso más allá que Meyer: Utilizó su tabla para predecir la existencia de elementos que tendrían propiedades similares al aluminio y al silicio, pero que aún eran desconocidos. Los descubrimientos del galio (1875) y del germanio (1886) supusieron un gran apoyo para los trabajos de Mendeleev. Aunque Mendeleev y Meyer mantuvieron una larga disputa sobre la prioridad, las contribuciones de Mendeleev al desarrollo de la tabla periódica son ahora más reconocidas ().
En el siglo XX, se hizo evidente que la relación periódica implicaba números atómicos en lugar de masas atómicas. El enunciado moderno de esta relación, la ley periódica, es el siguiente: las propiedades de los elementos son funciones periódicas de sus números atómicos. Una tabla periódica moderna organiza los elementos en orden creciente de sus números atómicos y agrupa los átomos con propiedades similares en la misma columna vertical (). Cada casilla representa un elemento y contiene su número atómico, símbolo, masa atómica promedio y (a veces) su nombre. Los elementos están dispuestos en siete filas horizontales, llamadas periodos o series, y 18 columnas verticales, llamadas grupos. Los grupos están marcados en la parte superior de cada columna. En los Estados Unidos, las marcaciones eran tradicionalmente números con letras mayúsculas. Sin embargo, la IUPAC recomienda que se utilicen los números del 1 al 18, y estas marcaciones son más comunes. Para que la tabla quepa en una sola página, se suelen escribir partes de dos de las filas, un total de 14 columnas, debajo del cuerpo principal de la tabla.
Incluso después de que la naturaleza periódica de los elementos y la propia tabla fueran ampliamente aceptadas, seguían existiendo lagunas. Mendeleev predijo, y otros, como Henry Moseley, lo confirmaron más tarde, que debía haber elementos por debajo del manganeso en el grupo 7. Los químicos alemanes Ida Tacke y Walter Noddack se propusieron encontrar los elementos, una búsqueda que continúan científicos de todo el mundo. Su método era único, ya que no solo tenían en cuenta las propiedades del manganeso, sino también los elementos horizontalmente adyacentes a los elementos 43 y 75 que faltaban en la tabla. Por lo tanto, al investigar las menas que contenían minerales de rutenio (Ru), wolframio (W), osmio (Os), etc., pudieron identificar elementos naturales que ayudaron a completar la tabla. El renio, uno de sus descubrimientos, fue uno de los últimos elementos naturales que se descubrieron y es el último elemento estable que se descubrió (el francio, el último elemento natural descubierto, fue identificado por Marguerite Perey en 1939).
Muchos elementos difieren drásticamente en sus propiedades químicas y físicas, pero algunos elementos son similares en sus comportamientos. Por ejemplo, muchos elementos tienen un aspecto brillante, son maleables (se pueden deformar sin romperse) y dúctiles (se pueden estirar en forma de alambres), y conducen bien el calor y la electricidad. Otros elementos no son brillantes, maleables o dúctiles, y son malos conductores del calor y la electricidad. Podemos clasificar los elementos en grandes clases con propiedades comunes: metales (elementos que son brillantes, maleables, buenos conductores del calor y la electricidad, sombreados en amarillo); no metales (elementos que parecen opacos, malos conductores del calor y la electricidad, sombreados en verde); y metaloides (elementos que conducen el calor y la electricidad moderadamente bien, y poseen algunas propiedades de los metales y otras de los no metales, sombreados en púrpura).
Los elementos también se pueden clasificar en los elementos del grupo principal (o elementos representativos) en las columnas marcadas como 1, 2 y 13 a 18; los metales de transición en las columnas marcadas como 3 a 12Según la definición de la IUPAC, los elementos del grupo 12 no son metales de transición, aunque a menudo se les llama así. En el capítulo dedicado a los metales de transición y la química de coordinación se ofrecen más detalles sobre los elementos de este grupo.y los metales de transición interna en las dos filas de la parte inferior de la tabla (los elementos de la fila superior se denominan lantánidos y los de la fila inferior actínidos; ). Los elementos pueden subdividirse en función de propiedades más específicas, como la composición de los compuestos que forman. Por ejemplo, los elementos del grupo 1 (la primera columna) forman compuestos que constan de un átomo del elemento y un átomo de hidrógeno. Estos elementos (excepto el hidrógeno) se conocen como metales alcalinos, y todos ellos tienen propiedades químicas similares. Los elementos del grupo 2 (la segunda columna) forman compuestos formados por un átomo del elemento y dos átomos de hidrógeno: Son los llamados metales alcalinotérreos, con propiedades similares entre los miembros de ese grupo. Otros grupos con nombres específicos son los pnictógenos (grupo 15), los calcógenos (grupo 16), los halógenos (grupo 17) y los gases nobles (grupo 18, también conocidos como gases inertes). También se puede hacer referencia a los grupos por el primer elemento del grupo: Por ejemplo, los calcógenos pueden denominarse grupo de oxígeno o familia de oxígeno. El hidrógeno es un elemento único, no metálico, con propiedades similares a los elementos del grupo 1 y del grupo 17. Por ello, el hidrógeno puede aparecer en la parte superior de ambos grupos, o por sí mismo.
Como podrá comprobar en sus estudios posteriores de química, los elementos que forman parte de un grupo suelen comportarse de forma similar. Esto se debe, en parte, al número de electrones de su capa exterior y a su similar disposición a enlazarse. Estas propiedades compartidas pueden tener implicaciones de gran alcance en la naturaleza, la ciencia y la medicina. Por ejemplo, cuando Gertrude Elion y George Hitchens investigaban formas de interrumpir la replicación de las células y los virus para luchar contra las enfermedades, utilizaron la similitud entre el azufre y el oxígeno (ambos en el grupo 16) y su capacidad de enlazarse de forma similar. Elion se centró en las purinas, que son componentes clave del ADN y que contienen oxígeno. Descubrió que, al introducir compuestos a base de azufre (llamados análogos de la purina) que imitan la estructura de las purinas, las moléculas del ADN se unían a los análogos en lugar de a la purina "normal" del ADN. Con la unión y la estructura normal del ADN alterada, Elion interrumpió con éxito la replicación celular. En el fondo, la estrategia funcionó por la similitud entre el azufre y el oxígeno. Su descubrimiento condujo directamente a importantes tratamientos para la leucemia. En general, el trabajo de Elion con George Hitchens no solo permitió obtener más tratamientos, sino que cambió toda la metodología del desarrollo de fármacos. Al utilizar elementos y compuestos específicos para atacar aspectos concretos de las células tumorales, los virus y las bacterias, sentaron las bases de muchos de los medicamentos actuales más comunes e importantes, utilizados para ayudar a millones de personas cada año. Se les otorgó el Premio Nobel en 1988.
Al estudiar la tabla periódica, es posible que haya notado algo sobre las masas atómicas de algunos de los elementos. El elemento 43 (tecnecio), el elemento 61 (prometio) y la mayoría de los elementos con número atómico 84 (polonio) y superiores tienen su masa atómica entre corchetes. Esto se hace en el caso de los elementos que están formados en su totalidad por isótopos inestables y radiactivos (aprenderá más sobre la radiactividad en el capítulo de química nuclear). No se puede determinar un peso atómico medio para estos elementos porque sus radioisótopos pueden variar significativamente en abundancia relativa, dependiendo de la fuente, o incluso pueden no existir en la naturaleza. El número entre corchetes es el número de masa atómica (una masa atómica aproximada) del isótopo más estable de ese elemento.
### Conceptos clave y resumen
El descubrimiento de la recurrencia periódica de propiedades similares entre los elementos condujo a la formulación de la tabla periódica, en la que los elementos están dispuestos en orden de número atómico creciente en filas conocidas como periodos y columnas conocidas como grupos. Los elementos del mismo grupo de la tabla periódica tienen propiedades químicas similares. Los elementos pueden clasificarse como metales, metaloides y no metales, o como elementos del grupo principal, metales de transición y metales de transición interna. Los grupos están numerados del 1 al 18 de izquierda a derecha. Los elementos del grupo 1 se conocen como metales alcalinos, los del grupo 2 son los metales alcalinotérreos, los del 15 son los pnictógenos, los del 16 son los calcógenos, los del 17 son los halógenos, y los del 18 son los gases nobles.
### Ejercicios de Química del final del capítulo
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# Átomos, moléculas e iones
## Compuestos iónicos y moleculares
En las reacciones químicas ordinarias, el núcleo de cada átomo (y, por lo tanto, la identidad del elemento) permanece inalterado. Sin embargo, los electrones pueden añadirse a los átomos por transferencia desde otros átomos, perderse por transferencia a otros átomos o compartirse con otros átomos. La transferencia y el intercambio de electrones entre los átomos rigen la química de los elementos. Durante la formación de algunos compuestos, los átomos ganan o pierden electrones y forman partículas cargadas eléctricamente llamadas iones ().
Puede utilizar la tabla periódica para predecir si un átomo formará un anión o un catión, y a menudo se puede predecir la carga del ion resultante. Los átomos de muchos metales del grupo principal pierden suficientes electrones para dejarlos con el mismo número de electrones que un átomo del gas noble anterior. Por ejemplo, un átomo de un metal alcalino (grupo 1) pierde un electrón y forma un catión con carga 1+; un metal alcalinotérreo (grupo 2) pierde dos electrones y forma un catión con carga 2+, y así sucesivamente. Por ejemplo, un átomo de calcio neutro, con 20 protones y 20 electrones, pierde fácilmente dos electrones. El resultado es un catión con 20 protones, 18 electrones y una carga 2+. Tiene el mismo número de electrones que los átomos del gas noble anterior, el argón, y se simboliza como Ca2+. El nombre de un ion metálico es el mismo que el del átomo metálico del que se forma, por lo que el Ca2+ se llama ion calcio.
Cuando los átomos de los elementos no metálicos forman iones, generalmente ganan suficientes electrones para tener el mismo número de electrones que un átomo del siguiente gas noble de la tabla periódica. Los átomos del grupo 17 ganan un electrón y forman aniones con carga 1-; los átomos del grupo 16 ganan dos electrones y forman iones con carga 2-, y así sucesivamente. Por ejemplo, el átomo neutro de bromo, con 35 protones y 35 electrones, puede ganar un electrón para disponer de 36 electrones. El resultado es un anión con 35 protones, 36 electrones y una carga de 1-. Tiene el mismo número de electrones que los átomos del siguiente gas noble, el criptón, y se simboliza como Br-. (En un capítulo posterior de este texto se ofrece una discusión de la teoría que apoya el estatus favorecido de los números de electrones de los gases nobles reflejados en estas reglas de predicción para la formación de iones).
Observe la utilidad de la tabla periódica para predecir la formación y la carga probable de los iones (). Al desplazarse del extremo izquierdo al derecho en la tabla periódica, los elementos del grupo principal tienden a formar cationes con una carga igual al número de grupo. Es decir, los elementos del grupo 1 forman iones 1+; los del grupo 2, iones 2+, y así sucesivamente. Al desplazarse del extremo derecho al izquierdo en la tabla periódica, los elementos suelen formar aniones con una carga negativa igual al número de grupos desplazados a la izquierda de los gases nobles. Por ejemplo, los elementos del grupo 17 (un grupo a la izquierda de los gases nobles) forman iones 1-; los elementos del grupo 16 (dos grupos a la izquierda) forman iones 2-, y así sucesivamente. Esta tendencia puede servir de guía en muchos casos, pero su valor predictivo disminuye cuando se avanza hacia el centro de la tabla periódica. De hecho, los metales de transición y algunos otros metales suelen presentar cargas variables que no son predecibles por su ubicación en la tabla. Por ejemplo, el cobre puede formar iones con una carga 1+ o 2+, y el hierro puede formar iones con una carga 2+ o 3+.
Los iones de los que hemos hablado hasta ahora se llaman iones monoatómicos, es decir, son iones formados por un solo átomo. También encontramos muchos iones poliatómicos. Estos iones, que actúan como unidades discretas, son moléculas cargadas eléctricamente (un grupo de átomos enlazados con una carga global). Algunos de los iones poliatómicos más importantes se enumeran en la . Los oxianiones son iones poliatómicos que contienen uno o más átomos de oxígeno. A estas alturas de su estudio de la química, debería memorizar los nombres, fórmulas y cargas de los iones poliatómicos más comunes. Como los utilizará repetidamente, pronto se le harán familiares.
Tenga en cuenta que existe un sistema para nombrar algunos iones poliatómicos; -ato e -ito son sufijos que designan iones poliatómicos que contienen más o menos átomos de oxígeno. Per- (abreviatura de "hiper") e hipo- (que significa "bajo") son prefijos que significan más átomos de oxígeno que -ato y menos átomos de oxígeno que -ito, respectivamente. Por ejemplo, el perclorato es el clorato es el clorito es y el hipoclorito es ClO-. Por desgracia, el número de átomos de oxígeno que corresponde a un sufijo o prefijo determinado no es coherente; por ejemplo, el nitrato es mientras que el sulfato es Esto se tratará con más detalle en el próximo módulo sobre nomenclatura.
La naturaleza de las fuerzas de atracción que mantienen unidos a los átomos o iones dentro de un compuesto es la base para clasificar el enlace químico. Cuando se transfieren electrones y se forman iones, se producen enlaces iónicos. Los enlaces iónicos son fuerzas electrostáticas de atracción, es decir, las fuerzas de atracción experimentadas entre objetos de carga eléctrica opuesta (en este caso, cationes y aniones). Cuando se "comparten" electrones y se forman moléculas, se producen enlaces covalentes. Los enlaces covalentes son las fuerzas de atracción entre los núcleos cargados positivamente de los átomos enlazados y uno o más pares de electrones que se encuentran entre los átomos. Los compuestos se clasifican como iónicos o moleculares (covalentes) en función de los enlaces presentes en ellos.
### Compuestos iónicos
Cuando un elemento compuesto por átomos que pierden fácilmente electrones (un metal) reacciona con un elemento compuesto por átomos que ganan fácilmente electrones (un no metal), suele producirse una transferencia de electrones que da lugar a iones. El compuesto formado por esta transferencia se estabiliza por las atracciones electrostáticas (enlaces iónicos) entre los iones de carga opuesta presentes en el compuesto. Por ejemplo, cuando cada átomo de sodio en una muestra de sodio metálico (grupo 1) cede un electrón para formar un catión de sodio, Na+, y cada átomo de cloro en una muestra de cloro gaseoso (grupo 17) acepta un electrón para formar un anión de cloruro, Cl-, el compuesto resultante, NaCl, está formado por iones de sodio e iones de cloruro en la proporción de un ion Na+ por cada ion Cl-. Del mismo modo, cada átomo de calcio (grupo 2) puede ceder dos electrones y transferir uno a cada uno de los dos átomos de cloro para formar CaCl2, que está compuesto por iones Ca2+ y Cl- en la proporción de un ion Ca2+ por dos iones Cl-.
Un compuesto que contiene iones y se mantiene unido por enlaces iónicos se llama compuesto iónico. La tabla periódica puede ayudarnos a reconocer muchos de los compuestos que son iónicos: Cuando un metal se combina con uno o más no metales, el compuesto suele ser iónico. Esta pauta funciona bien para predecir la formación de compuestos iónicos para la mayoría de los compuestos que se encuentran típicamente en un curso de introducción a la química. Sin embargo, no siempre es cierto (por ejemplo, el cloruro de aluminio, AlCl3, no es iónico).
A menudo se pueden reconocer los compuestos iónicos por sus propiedades. Los compuestos iónicos son sólidos que suelen fundirse a altas temperaturas y hervir a temperaturas aún más altas. Por ejemplo, el cloruro de sodio se funde a 801 °C y hierve a 1413 °C. (Como comparación, el compuesto molecular agua se funde a 0 °C y hierve a 100 °C) En forma sólida, un compuesto iónico no es conductor de electricidad porque sus iones no pueden fluir (la "electricidad" es el flujo de partículas cargadas). Sin embargo, cuando está fundido, puede conducir la electricidad porque sus iones pueden moverse libremente por el líquido ().
En todo compuesto iónico, el número total de cargas positivas de los cationes es igual al número total de cargas negativas de los aniones. Así, los compuestos iónicos son eléctricamente neutros en su conjunto, aunque contengan iones positivos y negativos. Podemos utilizar esta observación para ayudarnos a escribir la fórmula de un compuesto iónico. La fórmula de un compuesto iónico debe tener una proporción de iones tal que los números de cargas positivas y negativas sean iguales.
Muchos compuestos iónicos contienen iones poliatómicos () como el catión, el anión o ambos. Al igual que los compuestos iónicos simples, estos compuestos también deben ser eléctricamente neutros, por lo que sus fórmulas pueden predecirse tratando los iones poliatómicos como unidades discretas. Utilizamos paréntesis en una fórmula para indicar un grupo de átomos que se comportan como una unidad. Por ejemplo, la fórmula del fosfato de calcio, uno de los minerales de nuestros huesos, es Ca3(PO4)2. Esta fórmula indica que hay tres iones de calcio (Ca2+) por cada dos de grupos de fosfato . Los grupos son unidades discretas, cada una de ellas formada por un átomo de fósforo y cuatro de oxígeno, y con una carga global de 3-. El compuesto es eléctricamente neutro, y su fórmula muestra un recuento total de tres átomos de Ca, dos de P y ocho de O.
Dado que un compuesto iónico no está formado por moléculas individuales y discretas, no puede simbolizarse adecuadamente mediante una fórmula molecular. En cambio, los compuestos iónicos deben simbolizarse mediante una fórmula que indique el número relativo de sus iones constituyentes. Para los compuestos que solo contienen iones monoatómicos (como el NaCl) y para muchos compuestos que contienen iones poliatómicos (como el CaSO4), estas fórmulas son solo las fórmulas empíricas introducidas anteriormente en este capítulo. Sin embargo, las fórmulas de algunos compuestos iónicos que contienen iones poliatómicos no son fórmulas empíricas. Por ejemplo, el compuesto iónico oxalato de sodio está formado por iones Na+ y combinados en una proporción de 2:1, y su fórmula se escribe como Na2C2O4. Los subíndices de esta fórmula no son los números enteros más pequeños posibles, ya que cada uno puede dividirse entre 2 para obtener la fórmula empírica, NaCO2. Sin embargo, esta no es la fórmula aceptada para el oxalato de sodio, ya que no representa con exactitud el anión poliatómico del compuesto,
### Compuestos moleculares
Muchos compuestos no contienen iones, sino que están formados únicamente por moléculas discretas y neutras. Estos compuestos moleculares (compuestos covalentes) resultan cuando los átomos comparten, en lugar de transferir (ganar o perder), electrones. El enlace covalente es un concepto importante y extenso en química, y se tratará con bastante detalle en un capítulo posterior de este texto. A menudo podemos identificar los compuestos moleculares en función de sus propiedades físicas. En condiciones normales, los compuestos moleculares suelen existir como gases, líquidos de bajo punto de ebullición y sólidos de bajo punto de fusión, aunque existen muchas excepciones importantes.
Mientras que los compuestos iónicos suelen formarse cuando se combinan un metal y un no metal, los compuestos covalentes suelen formarse por una combinación de no metales. Por lo tanto, la tabla periódica puede ayudarnos a reconocer muchos de los compuestos que son covalentes. Aunque en este punto de nuestro estudio de la química podemos utilizar las posiciones de los elementos de un compuesto en la tabla periódica para predecir si es iónico o covalente, se debes ser consciente de que se trata de un enfoque muy simplista que no tiene en cuenta una serie de excepciones interesantes. Existen matices entre los compuestos iónicos y los moleculares, de los que aprenderá más adelante.
### Conceptos clave y resumen
Los metales (especialmente los de los grupos 1 y 2) tienden a perder el número de electrones que los dejaría con el mismo número de electrones que el gas noble anterior en la tabla periódica. De este modo, se forma un ion con carga positiva. Del mismo modo, los no metales (especialmente los de los grupos 16 y 17 y, en menor medida, los del grupo 15) pueden ganar el número de electrones necesario para proporcionar a los átomos el mismo número de electrones que en el siguiente gas noble de la tabla periódica. Por tanto, los no metales tienden a formar iones negativos. Los iones con carga positiva se llaman cationes y los de carga negativa, aniones. Los iones pueden ser monoatómicos (contienen un solo átomo) o poliatómicos (contienen más de un átomo).
Los compuestos que contienen iones se llaman compuestos iónicos. Los compuestos iónicos se forman generalmente a partir de metales y no metales. Los compuestos que no contienen iones, sino que están formados por átomos fuertemente unidos en moléculas (grupos de átomos sin carga que se comportan como una sola unidad), se llaman compuestos covalentes. Los compuestos covalentes suelen formarse a partir de dos no metales.
### Ejercicios de Química del final del capítulo
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# Átomos, moléculas e iones
## Nomenclatura química
La nomenclatura, un conjunto de reglas para nombrar las cosas, es importante en la ciencia y en muchas otras situaciones. Este módulo describe un enfoque que se utiliza para nombrar compuestos iónicos y moleculares simples, como NaCl, CaCO3 y N2O4. Los más sencillos son los compuestos binarios, los que contienen solo dos elementos, pero también consideraremos cómo nombrar los compuestos iónicos que contienen iones poliatómicos, y una clase específica y muy importante de compuestos conocidos como ácidos (los capítulos siguientes de este texto se centrarán en estos compuestos con gran detalle). Nos limitaremos aquí a los compuestos inorgánicos, compuestos que están formados principalmente por elementos distintos del carbono, y seguiremos las directrices de nomenclatura propuestas por la IUPAC. Las reglas de los compuestos orgánicos, en los que el carbono es el elemento principal, se tratarán en un capítulo posterior sobre química orgánica.
### Compuestos iónicos
Para nombrar un compuesto inorgánico, debemos tener en cuenta las respuestas a las siguientes preguntas. En primer lugar, ¿el compuesto es iónico o molecular? Si el compuesto es iónico, ¿el metal forma iones de un solo tipo (carga fija) o de más de un tipo (carga variable)? ¿Los iones son monoatómicos o poliatómicos? Si el compuesto es molecular, ¿contiene hidrógeno? Si es así, ¿también contiene oxígeno? A partir de las respuestas que obtenemos, colocamos el compuesto en una categoría adecuada y le damos el nombre correspondiente.
### Compuestos que solo contienen iones monoatómicos
El nombre de un compuesto binario que contiene iones monoatómicos consiste en el nombre del catión (el nombre del metal) seguido del nombre del anión (el nombre del elemento no metálico con su terminación sustituida por el sufijo -uro). Algunos ejemplos se recogen en la .
### Compuestos que contienen iones poliatómicos
Los compuestos que contienen iones poliatómicos se nombran de forma similar a los que solo contienen iones monoatómicos, es decir, nombrando primero el catión y luego el anión. Los ejemplos se muestran en la .
### Compuestos que contienen un ion metálico con carga variable
La mayoría de los metales de transición y algunos metales del grupo principal pueden formar dos o más cationes con cargas diferentes. Los compuestos de estos metales con no metales se nombran con el mismo método que los compuestos de la primera categoría, salvo que la carga del ion metálico se especifica con un número romano entre paréntesis después del nombre del metal. La carga del ion metálico se determina a partir de la fórmula del compuesto y la carga del anión. Por ejemplo, consideremos los compuestos iónicos binarios de hierro y cloro. El hierro suele presentar una carga de 2+ o 3+ (vea la ), y las dos fórmulas compuestas correspondientes son FeCl2 y FeCl3. El nombre más sencillo, "cloruro de hierro", será en este caso ambiguo, ya que no distingue entre estos dos compuestos. En estos casos, la carga del ion metálico se incluye como un número romano entre paréntesis inmediatamente después del nombre del metal. Estos dos compuestos se denominan inequívocamente cloruro de hierro(II) y cloruro de hierro(III), respectivamente. Otros ejemplos se encuentran en la .
La nomenclatura anticuada utilizaba los sufijos -ico y -oso para designar los metales con mayor y menor carga, respectivamente: El cloruro de hierro(III), FeCl3, se denominaba anteriormente cloruro férrico, y el cloruro de hierro(II), FeCl2, se conocía como cloruro ferroso. Aunque la comunidad científica ha abandonado en gran medida esta convención de nomenclatura, sigue siendo utilizada por algunos segmentos de la industria. Por ejemplo, puede ver las palabras fluoruro de estañoso en un tubo de pasta de dientes. Esto representa la fórmula SnF2, que se denomina más correctamente fluoruro de estaño(II). El otro fluoruro de estaño es el SnF4, que antes se llamaba fluoruro estánico, pero que ahora se denomina fluoruro de estaño(IV).
### Hidratos iónicos
Los compuestos iónicos que contienen moléculas de agua como componentes integrales de sus cristales se denominan hidratos. El nombre de un hidrato iónico se obtiene añadiendo un término al nombre del compuesto anhidro (que significa "no hidratado") que indica el número de moléculas de agua asociadas a cada unidad de fórmula del compuesto. La palabra añadida comienza con un prefijo griego que denota el número de moléculas de agua (vea la ) y termina con "hidrato”. Por ejemplo, el compuesto anhidro de sulfato de cobre(II) también existe como un hidrato que contiene cinco moléculas de agua y se denomina sulfato de cobre(II) pentahidratado. La sosa es el nombre común de un hidrato de carbonato de sodio que contiene 10 moléculas de agua; el nombre sistemático es carbonato de sodio decahidratado.
Las fórmulas de los hidratos iónicos se escriben añadiendo un punto centrado verticalmente, un coeficiente que representa el número de moléculas de agua y la fórmula del agua. Los dos ejemplos mencionados en el párrafo anterior están representados por las fórmulas
### Compuestos moleculares (covalentes)
Las características de enlace de los compuestos moleculares inorgánicos son diferentes a las de los compuestos iónicos, y también se nombran utilizando un sistema diferente. Las cargas de los cationes y aniones dictan sus proporciones en los compuestos iónicos, por lo que especificar los nombres de los iones proporciona información suficiente para determinar las fórmulas químicas. Sin embargo, como el enlace covalente permite una variación significativa en las relaciones de combinación de los átomos de una molécula, los nombres de los compuestos moleculares deben identificar explícitamente estas relaciones.
### Compuestos formados por dos elementos
Cuando dos elementos no metálicos forman un compuesto molecular, suelen ser posibles varias relaciones de combinación. Por ejemplo, el carbono y el oxígeno pueden formar los compuestos CO y CO2. Como se trata de sustancias diferentes con propiedades distintas, no pueden tener ambas el mismo nombre (no pueden llamarse ambas óxido de carbono). Para hacer frente a esta situación, utilizamos un método de nomenclatura algo similar al utilizado para los compuestos iónicos, pero con prefijos añadidos para especificar el número de átomos de cada elemento. El nombre del elemento más metálico (el que está más a la izquierda o abajo de la tabla periódica) va primero, seguido del nombre del elemento que sea más no metálico (el que está más a la derecha o arriba) con su terminación cambiada por el sufijo -uro. Los números de átomos de cada elemento se designan con los prefijos griegos que aparecen en la .
Cuando solo hay un átomo del primer elemento, se suele eliminar el prefijo mono- de esa parte. Así, el CO se denomina monóxido de carbono y CO2 dióxido de carbono. Cuando dos vocales son adyacentes, la a del prefijo griego se suele suprimir. Algunos otros ejemplos se muestran en la .
Hay algunos nombres comunes que encontrará a medida que continúe su estudio de la química. Por ejemplo, aunque el NO se llama a menudo óxido nítrico, su nombre correcto es monóxido de nitrógeno. Del mismo modo, el N2O se conoce como óxido nitroso aunque nuestras normas especificarían el nombre de monóxido de dinitrógeno. (Y el H2O suele llamarse agua, no monóxido de dihidrógeno). Debe memorizar los nombres comunes de los compuestos a medida que los encuentre.
### Ácidos binarios
Algunos compuestos que contienen hidrógeno son miembros de una importante clase de sustancias conocidas como ácidos. La química de estos compuestos se explora con más detalle en capítulos posteriores de este texto, pero por ahora bastará con señalar que muchos ácidos liberan iones de hidrógeno, H+, cuando se disuelven en agua. Para denotar esta propiedad química distintiva, una mezcla de agua con un ácido recibe un nombre derivado del nombre del compuesto. Si el compuesto es un ácido binario (formado por hidrógeno y otro elemento no metálico):
1. La palabra "hidrógeno" se cambia por el prefijo hidro-
2. El nombre del otro elemento no metálico se modifica añadiendo el sufijo -ico
3. La palabra "ácido" se agrega como segunda palabra
Por ejemplo, cuando el gas HCl (cloruro de hidrógeno) se disuelve en agua, la solución se llama ácido clorhídrico. Otros ejemplos de esta nomenclatura se muestran en la .
### Oxiácidos
Muchos compuestos que contienen tres o más elementos (como los compuestos orgánicos o de coordinación) están sujetos a reglas de nomenclatura especializadas que aprenderá más adelante. Sin embargo, hablaremos brevemente de los importantes compuestos conocidos como oxiácidos, compuestos que contienen hidrógeno, oxígeno y al menos otro elemento, y que se enlazan de tal manera que imparten propiedades ácidas al compuesto (aprenderá los detalles de esto en un capítulo posterior). Los oxiácidos típicos están formados por hidrógeno combinado con un ion poliatómico que contiene oxígeno. Para nombrar a los oxiácidos:
1. Omita el "hidrógeno"
2. Comience con el nombre de la raíz del anión
3. Sustituya –ato con –ico, o –ito con –oso
4. Añada "ácido"
Por ejemplo, consideremos el H2CO3 (que podríamos llamar "carbonato de hidrógeno"). Para nombrarlo correctamente, se omite el "hidrógeno"; se sustituye el –ato de carbonato por –ico; y se añade ácido, por lo que su nombre es ácido carbónico. Otros ejemplos se encuentran en la . Hay algunas excepciones al método general de denominación (por ejemplo, el H2SO4 se denomina ácido sulfúrico, no ácido súlfico, y el H2SO3 es ácido sulfuroso, no ácido sulfoso).
### Conceptos clave y resumen
Los químicos utilizan reglas de nomenclatura para nombrar claramente los compuestos. Los compuestos iónicos y moleculares se nombran con métodos algo diferentes. Los compuestos iónicos binarios suelen estar formados por un metal y un no metal. Primero se escribe el nombre del metal, seguido del nombre del no metal con su terminación cambiada auro/ido. Por ejemplo, el K2O se llama óxido de potasio. Si el metal puede formar iones con diferentes cargas, un número romano entre paréntesis sigue al nombre del metal para especificar su carga. Así, el FeCl2 es cloruro de hierro(II) y el FeCl3 es cloruro de hierro(III). Algunos compuestos contienen iones poliatómicos; hay que memorizar los nombres de los iones poliatómicos más comunes. Los compuestos moleculares pueden formar compuestos con diferentes proporciones de sus elementos, por lo que se utilizan prefijos para especificar el número de átomos de cada elemento en una molécula del compuesto. Algunos ejemplos son el SF6, hexafluoruro de azufre, y el N2O4, tetróxido de dinitrógeno. Los ácidos son una clase importante de compuestos que contienen hidrógeno y tienen reglas de nomenclatura especiales. Los ácidos binarios se nombran utilizando el prefijo hidro-, cambiando el sufijo -uro por -ico y añadiendo "ácido"; HCl es ácido clorhídrico. Los oxiácidos se nombran cambiando la terminación del anión (–ato a –ico e –ito a –oso), y añadiendo "ácido"; H2CO3 es ácido carbónico.
### Ejercicios de Química del final del capítulo
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# Composición de sustancias y soluciones
## Introducción
Las piscinas han sido durante mucho tiempo un medio popular de recreo, ejercicio y terapia física. Dado que no es práctico llenar las piscinas grandes con agua dulce con frecuencia, el agua de la piscina se trata regularmente con productos químicos para evitar el crecimiento de bacterias y algas dañinas. El mantenimiento adecuado de la piscina requiere la adición periódica de diversos compuestos químicos en cantidades medidas con cuidado. Por ejemplo, la cantidad relativa de iones de calcio, Ca2+, en el agua debe mantenerse dentro de ciertos límites para prevenir la irritación de los ojos y evitar daños en el fondo de la piscina y en las tuberías. Para mantener los niveles adecuados de calcio, se añaden los cationes de calcio al agua en forma de un compuesto iónico que también contiene aniones; por lo tanto, es necesario conocer tanto la cantidad relativa de Ca2+ en el compuesto como el volumen de agua de la piscina para conseguir el nivel adecuado de calcio. Los aspectos cuantitativos de la composición de las sustancias (como el compuesto que contiene calcio) y de las mezclas (como el agua de la piscina) son objeto de este capítulo. |
# Composición de sustancias y soluciones
## La fórmula de masa y el concepto de mol
Muchos sostienen que la ciencia química moderna comenzó cuando los científicos empezaron a explorar los aspectos cuantitativos y cualitativos de la química. Por ejemplo, la teoría atómica de Dalton fue un intento de explicar los resultados de las mediciones que le permitieron calcular las masas relativas de los elementos combinados en diversos compuestos. Entender la relación entre las masas de los átomos y las fórmulas químicas de los compuestos nos permite describir cuantitativamente la composición de las sustancias.
### Fórmula de masa
En un capítulo anterior de este texto se describía el desarrollo de la unidad de masa atómica, el concepto de masas atómicas promedio y el uso de fórmulas químicas para representar la composición elemental de las sustancias. Estas ideas pueden ampliarse para calcular la fórmula de masa de una sustancia sumando las masas atómicas promedio de todos los átomos representados en la fórmula de la sustancia.
### Fórmula de masa de las sustancias covalentes
En el caso de las sustancias covalentes, la fórmula representa el número y el tipo de átomos que componen una única molécula de la sustancia; por tanto, la fórmula de masa puede denominarse correctamente masa molecular. Pensemos en el cloroformo (CHCl3), un compuesto covalente que en su día se utilizaba como anestesia quirúrgica y que ahora se emplea principalmente en la producción de tetrafluoroetileno, el componente básico del polímero "antiadherente", el teflón. La fórmula molecular del cloroformo indica que una sola molécula contiene un átomo de carbono, uno de hidrógeno y tres de cloro. La masa molecular promedio de una molécula de cloroformo es, por tanto, igual a la suma de las masas atómicas promedio de estos átomos. La resume los cálculos utilizados para obtener la masa molecular del cloroformo, que es de 119,37 u.
Asimismo, la masa molecular de una molécula de aspirina, C9H8O4, es la suma de las masas atómicas de nueve átomos de carbono, ocho átomos de hidrógeno y cuatro átomos de oxígeno, que asciende a 180,15 u ().
### Fórmula de masa de los compuestos iónicos
Los compuestos iónicos están formados por cationes y aniones discretos combinados en proporciones que dan lugar a una materia masiva eléctricamente neutra. La fórmula de masa de un compuesto iónico se calcula de la misma manera que la fórmula de masa de los compuestos covalentes: sumando las masas atómicas promedio de todos los átomos de la fórmula del compuesto. Sin embargo, hay que tener en cuenta que la fórmula de un compuesto iónico no representa la composición de una molécula discreta, por lo que no puede denominarse correctamente "masa molecular”.
Como ejemplo, consideremos el cloruro de sodio, NaCl, el nombre químico de la sal de mesa común. El cloruro de sodio es un compuesto iónico formado por cationes de sodio, Na+, y aniones de cloruro, Cl-, combinados en una relación 1:1. La fórmula de masa de este compuesto se calcula en 58,44 u (vea la ).
Observe que en este cálculo se han utilizado las masas medias de los átomos neutros de sodio y cloro, en lugar de las masas de los cationes de sodio y los aniones de cloro. Este enfoque es perfectamente aceptable cuando se calcula la fórmula de masa de un compuesto iónico. Aunque un catión de sodio tiene una masa ligeramente menor que un átomo de sodio (ya que le falta un electrón), esta diferencia se verá compensada por el hecho de que un anión de cloruro es ligeramente más masivo que un átomo de cloruro (debido al electrón extra). Además, la masa de un electrón es insignificante con respecto a la masa de un átomo típico. Incluso cuando se calcula la masa de un ion aislado, los electrones faltantes o adicionales pueden generalmente ignorarse, ya que su contribución a la masa total es insignificante, reflejándose solo en los dígitos no significativos que se perderán al redondear adecuadamente la masa calculada. Las pocas excepciones a esta norma son los iones muy ligeros derivados de elementos con masas atómicas conocidas con precisión.
### El mol
La identidad de una sustancia se define no solo por los tipos de átomos o iones que contiene, sino por la cantidad de cada tipo de átomo o ion. Por ejemplo, el agua, H2O, y el peróxido de hidrógeno, H2O2, se parecen en que sus respectivas moléculas están compuestas por átomos de hidrógeno y oxígeno. Sin embargo, como una molécula de peróxido de hidrógeno contiene dos átomos de oxígeno, a diferencia de la molécula de agua, que solo tiene uno, ambas sustancias presentan propiedades muy diferentes. Hoy en día, instrumentos sofisticados permiten la medición directa de estos rasgos microscópicos definitorios; sin embargo, los mismos rasgos se derivaron originalmente de la medición de las propiedades macroscópicas (las masas y los volúmenes de las cantidades de materia a granel) utilizando herramientas relativamente simples (balanzas y cristalería volumétrica). Este enfoque experimental requirió la introducción de una nueva unidad para la cantidad de sustancias, el mol, que sigue siendo indispensable en la ciencia química moderna.
El mol es una unidad de cantidad similar a las unidades familiares como el par, la docena, el bruto, etc. Proporciona una medida específica del número de átomos o moléculas en una muestra de materia. Una de las connotaciones latinas de la palabra "mol" es "gran masa" o “gran cantidad", lo que coincide con su uso como nombre de esta unidad. El mol proporciona un vínculo entre una propiedad macroscópica fácil de medir, la masa aparente, y una propiedad fundamental extremadamente importante, el número de átomos, moléculas, etc. Un mol de sustancia es la cantidad en la que hay 6,02214076 1023 entidades discretas (átomos o moléculas). Este gran número es una constante fundamental conocida como número de Avogadro ( o constante de Avogadro en honor al científico italiano Amedeo Avogadro. Esta constante se indica correctamente con una unidad explícita de "por mol", siendo una versión convenientemente redondeada 6,022 1023/mol.
De acuerdo con su definición como unidad de cantidad, 1 mol de cualquier elemento contiene el mismo número de átomos que 1 mol de cualquier otro elemento. Sin embargo, las masas de 1 mol de diferentes elementos son diferentes, ya que las masas de los átomos individuales son drásticamente diferentes. La masa molar de un elemento (o compuesto) es la masa en gramos de 1 mol de esa sustancia, propiedad que se expresa en unidades de gramos por mol (g/mol) (vea la ).
La masa molar de cualquier sustancia equivale numéricamente a su peso atómico o de fórmula en u. Según la definición de u, un solo átomo 12C pesa 12 u (su masa atómica es de 12 u). Un mol de 12C pesa 12 g (su masa molar es 12 g/mol). Esta relación es válida para todos los elementos, ya que sus masas atómicas se miden en relación con la de la sustancia de referencia de u, 12C. Ampliando este principio, la masa molar de un compuesto en gramos es igualmente equivalente numéricamente a su fórmula de masa en u ().
Aunque la masa atómica y la masa molar son numéricamente equivalentes, hay que tener en cuenta que son enormemente diferentes en términos de escala, como lo representa la gran diferencia en las magnitudes de sus respectivas unidades (u frente a g). Para apreciar la enormidad del mol, considere una pequeña gota de agua que pesa aproximadamente 0,03 g (vea la ). Aunque esto representa solo una pequeña fracción de 1 mol de agua (~18 g), contiene más moléculas de agua de las que se pueden imaginar claramente. Si las moléculas se distribuyeran por igual entre los aproximadamente siete mil millones de habitantes de la Tierra, cada persona recibiría más de 100 mil millones de moléculas.
Las relaciones entre la fórmula de masa, el mol y el número de Avogadro pueden aplicarse para calcular diversas cantidades que describen la composición de sustancias y compuestos, como se demuestra en los siguientes problemas de ejemplo.
### Conceptos clave y resumen
La fórmula de masa de una sustancia es la suma de las masas atómicas promedio de cada átomo representado en la fórmula química y se expresa en unidades de masa atómica. La fórmula de masa de un compuesto covalente también se llama masa molecular. Una unidad de cantidad conveniente para expresar números muy grandes de átomos o moléculas es el mol. Las mediciones experimentales han determinado que el número de entidades que componen 1 mol de sustancia es de 6,022 1023, una cantidad llamada número de Avogadro. La masa en gramos de 1 mol de sustancia es su masa molar. Debido al uso de la misma sustancia de referencia para definir la unidad de masa atómica y el mol, la fórmula de masa (u) y la masa molar (g/mol) de cualquier sustancia son numéricamente equivalentes (por ejemplo, una molécula de H2O pesa aproximadamente 18 u y 1 mol de moléculas de H2O pesa aproximadamente 18 g).
### Ejercicios de Química del final del capítulo
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# Composición de sustancias y soluciones
## Determinación de fórmulas empíricas y moleculares
En el apartado anterior se ha tratado la relación entre la masa aparente de una sustancia y el número de átomos o moléculas que contiene (moles). Dada la fórmula química de la sustancia, se puede determinar su cantidad (moles) a partir de su masa, y viceversa. Pero ¿qué ocurre si se desconoce la fórmula química de una sustancia? En esta sección, estos mismos principios se aplicarán para derivar las fórmulas químicas de sustancias desconocidas a partir de mediciones experimentales de masa.
### Composición porcentual
La composición elemental de un compuesto define su identidad química y las fórmulas químicas son la forma más sucinta de representar esta composición elemental. Cuando se desconoce la fórmula de un compuesto, la medición de la masa de cada uno de sus elementos constitutivos suele ser el primer paso en el proceso de determinación experimental de la fórmula. Los resultados de estas mediciones permiten calcular la composición porcentual del compuesto, definida como el porcentaje en masa de cada elemento en el compuesto. Por ejemplo, consideremos un compuesto gaseoso formado únicamente por carbono e hidrógeno. La composición porcentual de este compuesto podría representarse como sigue:
Si el análisis de una muestra de 10,0 g de este gas muestra que contiene 2,5 g de H y 7,5 g de C, la composición porcentual se calcularía en un 25 % de H y un 75 % de C:
### Determinar la composición porcentual a partir de fórmulas moleculares o empíricas
La composición porcentual también es útil para evaluar la abundancia relativa de un elemento determinado en diferentes compuestos de fórmulas conocidas. Como ejemplo, consideremos los fertilizantes comunes que contienen nitrógeno: amoníaco (NH3), nitrato de amonio (NH4NO3) y urea (CH4N2O). El elemento nitrógeno es el ingrediente activo para fines agrícolas, por lo que el porcentaje de masa de nitrógeno en el compuesto es una preocupación práctica y económica para los consumidores que eligen entre estos fertilizantes. Para este tipo de aplicaciones, la composición porcentual de un compuesto se obtiene fácilmente a partir de su fórmula de masa y de las masas atómicas de sus elementos constitutivos. Una molécula de NH3 contiene un átomo de N que pesa 14,01 u y tres átomos de H que pesan un total de (3 1,008 u) = 3,024 u. La fórmula de masa del amoníaco es, por tanto, (14,01 u + 3,024 u) = 17,03 u, y su composición porcentual es:
Este mismo enfoque puede adoptarse considerando un par de moléculas, una docena de moléculas o un mol de moléculas, etc. Esta última cantidad es la más conveniente y simplemente implicaría el uso de masas molares en lugar de fórmulas de masa y atómicas, como se ha demostrado en el . Siempre que se conozca la fórmula molecular o empírica del compuesto en cuestión, la composición porcentual puede derivarse de las masas atómicas o molares de los elementos del compuesto.
### Determinación de fórmulas empíricas
Como se ha mencionado anteriormente, el enfoque más común para determinar la fórmula química de un compuesto es medir primero las masas de sus elementos constitutivos. Sin embargo, hay que tener en cuenta que las fórmulas químicas representan los números relativos, no las masas, de los átomos de la sustancia. Por lo tanto, cualquier dato derivado experimentalmente que involucre la masa debe ser utilizado para derivar los números correspondientes de átomos en el compuesto. Esto se consigue utilizando las masas molares para convertir la masa de cada elemento en un número de moles. Estas cantidades molares se utilizan para calcular las relaciones de números enteros que pueden utilizarse para obtener la fórmula empírica de la sustancia. Considere una muestra de compuesto que contiene 1,71 g de C y 0,287 g de H. Los números correspondientes de átomos (en moles) son:
Por lo tanto, este compuesto puede estar representado por la fórmula C0,142H0,284. Por convención, las fórmulas contienen subíndices de números enteros, lo que puede lograrse dividiendo cada subíndice por el subíndice menor:
(Recordemos que los subíndices de "1" no se escriben, sino que se suponen si no hay ningún otro número)
La fórmula empírica de este compuesto es, pues, CH2. Esta puede ser o no la fórmula molecular del compuesto; sin embargo, se necesita información adicional para hacer esa determinación (como se trata más adelante en esta sección).
Consideremos como otro ejemplo una muestra de compuesto que se ha determinado que contiene 5,31 g de Cl y 8,40 g de O. Siguiendo el mismo enfoque se obtiene una fórmula empírica tentativa de:
En este caso, al dividir por el subíndice más pequeño todavía nos queda un subíndice decimal en la fórmula empírica. Para convertir esto en un número entero, multiplique cada uno de los subíndices por dos, conservando la misma proporción de átomos y dando como resultado Cl2O7 como fórmula empírica final.
En resumen, las fórmulas empíricas se derivan de las masas de los elementos que se miden experimentalmente al:
1. Derivar el número de moles de cada elemento a partir de su masa.
2. Dividir la cantidad molar de cada elemento entre la cantidad molar más pequeña para obtener los subíndices de una fórmula empírica tentativa.
3. Multiplicar todos los coeficientes por un número entero, si es necesario, para garantizar que se obtiene la menor relación de números enteros de los subíndices.
En la se describe este procedimiento en forma de diagrama de flujo para una sustancia que contiene los elementos A y X.
### Derivar fórmulas empíricas a partir de la composición porcentual
Por último, con respecto a la derivación de fórmulas empíricas, considere los casos en los que se dispone de la composición porcentual de un compuesto en lugar de las masas absolutas de los elementos que lo componen. En estos casos, la composición porcentual puede utilizarse para calcular las masas de los elementos presentes en cualquier masa conveniente del compuesto; estas masas pueden utilizarse entonces para derivar la fórmula empírica de la manera habitual.
### Calcular fórmulas moleculares
Recordemos que las fórmulas empíricas son símbolos que representan los números relativos de los elementos de un compuesto. Para determinar el número absoluto de átomos que componen una única molécula de un compuesto covalente es necesario conocer tanto su fórmula empírica como su masa molecular o masa molar. Estas magnitudes pueden determinarse experimentalmente mediante diversas técnicas de medición. La masa molecular, por ejemplo, suele obtenerse a partir del espectro de masas del compuesto (vea el análisis de esta técnica en el capítulo anterior sobre átomos y moléculas). La masa molar puede medirse mediante una serie de métodos experimentales, muchos de los cuales se presentarán en capítulos posteriores de este texto.
Las fórmulas moleculares se obtienen comparando la masa molecular o molar del compuesto con su masa de fórmula empírica. Como su nombre indica, una masa de fórmula empírica es la suma de las masas atómicas promedio de todos los átomos representados en una fórmula empírica. Si se conoce la masa molecular (o molar) de la sustancia, puede dividirse por la masa de fórmula empírica para obtener el número de unidades de fórmula empírica por molécula(n):
La fórmula molecular se obtiene entonces multiplicando cada subíndice de la fórmula empírica por n, como muestra la fórmula empírica genérica AxBy:
Por ejemplo, consideremos un compuesto covalente cuya fórmula empírica se determina como CH2O. La masa de fórmula empírica de este compuesto es de aproximadamente 30 u (la suma de 12 u para un átomo de C, 2 u para dos átomos de H y 16 u para un átomo de O). Si se determina que la masa molecular del compuesto es de 180 u, esto indica que las moléculas de este compuesto contienen seis veces el número de átomos representados en la fórmula empírica:
Las moléculas de este compuesto se representan entonces con fórmulas moleculares cuyos subíndices son seis veces mayores que los de la fórmula empírica:
Observe que este mismo enfoque puede utilizarse cuando se emplea la masa molar (g/mol) en lugar de la masa molecular (u). En este caso, se considera un mol de unidades y moléculas de fórmula empírica, a diferencia de las unidades y moléculas individuales.
### Conceptos clave y resumen
La identidad química de una sustancia se define por los tipos y números relativos de átomos que componen sus entidades fundamentales (moléculas en el caso de los compuestos covalentes, iones en el caso de los compuestos iónicos). La composición porcentual de un compuesto proporciona el porcentaje de masa de cada elemento en el compuesto, y a menudo se determina experimentalmente y se utiliza para derivar la fórmula empírica del compuesto. La masa de la fórmula empírica de un compuesto covalente puede compararse con la masa molecular o molar del compuesto para obtener una fórmula molecular.
### Ecuaciones clave
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# Composición de sustancias y soluciones
## Molaridad
Las secciones anteriores de este capítulo se centraron en la composición de las sustancias: muestras de materia que contienen un solo tipo de elemento o compuesto. Sin embargo, las mezclas (muestras de materia que contienen dos o más sustancias combinadas físicamente) son más frecuentes en la naturaleza que las sustancias puras. Al igual que una sustancia pura, la composición relativa de una mezcla desempeña un papel importante en la determinación de sus propiedades. La cantidad relativa de oxígeno en la atmósfera de un planeta determina su capacidad para mantener la vida aeróbica. Las cantidades relativas de hierro, carbono, níquel y otros elementos en el acero (una mezcla conocida como "aleación") determinan su fuerza física y su resistencia a la corrosión. La cantidad relativa del principio activo de un medicamento determina su eficacia para conseguir el efecto farmacológico deseado. La cantidad relativa de azúcar en una bebida determina su dulzor (vea la ). Esta sección describirá una de las formas más comunes de cuantificar las composiciones relativas de las mezclas.
### Soluciones
Las soluciones se han definido previamente como mezclas homogéneas, lo que significa que la composición de la mezcla (y por tanto sus propiedades) es uniforme en todo su volumen. Las soluciones son frecuentes en la naturaleza y también se han utilizado en diversas formas de tecnología creada por el hombre. En el capítulo sobre soluciones y coloides se ofrece un tratamiento más exhaustivo de las propiedades de las soluciones, pero aquí se ofrece una introducción a algunas de las propiedades básicas de las soluciones.
La cantidad relativa de un determinado componente de la solución se conoce como su concentración. A menudo, aunque no siempre, una solución contiene un componente con una concentración significativamente mayor que la de todos los demás componentes. Este componente se denomina solvente y puede considerarse como el medio en el que se dispersan o disuelven los demás componentes. Las soluciones en las que el agua es el solvente son, por supuesto, muy comunes en nuestro planeta. Una solución en la que el agua es el solvente se llama solución acuosa.
Un soluto es un componente de una solución que suele estar presente en una concentración mucho menor que la del solvente. Las concentraciones de solutos suelen describirse con términos cualitativos como diluida (de concentración relativamente baja) y concentrada (de concentración relativamente alta).
Las concentraciones pueden evaluarse cuantitativamente utilizando una amplia variedad de unidades de medida, cada una de ellas conveniente para aplicaciones particulares. La molaridad ( es una unidad de concentración útil para muchas aplicaciones en química. La molaridad se define como el número de moles de soluto en exactamente 1 litro (1 L) de la solución:
Cuando se realizan cálculos por etapas, como en el , es importante abstenerse de redondear los resultados de los cálculos intermedios, lo que puede dar lugar a errores de redondeo en el resultado final. En el , la cantidad molar de NaCl calculada en el primer paso, 1,325 mol, se redondearía correctamente a 1,32 mol si se tuviera que informar; sin embargo, aunque el último dígito (5) no es significativo, debe conservarse como dígito de guardia en el cálculo intermedio. Si no se hubiera retenido el dígito de guardia, el cálculo final de la masa de NaCl habría sido de 77,1 g, una diferencia de 0,3 g.
Además de conservar un dígito de guardia para los cálculos intermedios, también se pueden evitar los errores de redondeo realizando los cálculos en un solo paso (vea el ). Esto elimina los pasos intermedios para que solo se redondee el resultado final.
### Dilución de soluciones
La dilución es el proceso por el que se reduce la concentración de una solución mediante la adición de un solvente. Por ejemplo, un vaso de té helado se diluye cada vez más a medida que se derrite el hielo. El agua del hielo derretido aumenta el volumen del solvente (agua) y el volumen global de la solución (té helado), reduciendo así las concentraciones relativas de los solutos que dan sabor a la bebida ().
La dilución es también un medio habitual para preparar soluciones de una concentración deseada. Añadiendo solvente a una porción medida de una solución madre más concentrada, se puede preparar una solución de menor concentración. Por ejemplo, los plaguicidas comerciales suelen venderse como soluciones en las que los ingredientes activos están mucho más concentrados de lo que es apropiado para su aplicación. Antes de poder utilizarlos en los cultivos, los plaguicidas deben diluirse. Esta es también una práctica muy común para la preparación de una serie de reactivos comunes de laboratorio.
Se puede utilizar una relación matemática sencilla para relacionar los volúmenes y las concentraciones de una solución antes y después del proceso de dilución. Según la definición de molaridad, el número de moles de soluto en una solución (n) es igual al producto de la molaridad de la solución (M) por su volumen en litros (L):
Expresiones como estas pueden escribirse para una solución antes y después de diluirla:
donde los subíndices "1" y "2" se refieren a la solución antes y después de la dilución, respectivamente. Como el proceso de dilución no cambia la cantidad de soluto en la solución, n1 = n2. Por lo tanto, estas dos ecuaciones pueden ser iguales entre sí:
Esta relación se denomina comúnmente ecuación de dilución. Aunque esta ecuación utiliza la molaridad como unidad de concentración y los litros como unidad de volumen, se pueden utilizar otras unidades de concentración y volumen siempre que las unidades se cancelen adecuadamente según el método de los factores de conversión. Reflejando esta versatilidad, la ecuación de dilución se escribe a menudo en la forma más general:
donde C y V son la concentración y el volumen, respectivamente.
### Conceptos clave y resumen
Las soluciones son mezclas homogéneas. Muchas soluciones contienen un componente, llamado solvente, en el que se disuelven otros componentes, llamados solutos. Una solución acuosa es aquella cuyo solvente es el agua. La concentración de una solución es una medida de la cantidad relativa de soluto en una cantidad determinada de solución. Las concentraciones pueden medirse utilizando varias unidades, y una unidad muy útil es la molaridad, que se define como el número de moles de soluto por litro de solución. La concentración de soluto de una solución puede disminuirse añadiendo solvente, proceso que se denomina dilución. La ecuación de dilución es una relación simple entre las concentraciones y los volúmenes de una solución antes y después de la dilución.
### Ejercicios de Química del final del capítulo
### Ecuaciones clave
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# Composición de sustancias y soluciones
## Otras unidades para las concentraciones de las soluciones
En el apartado anterior se ha introducido la molaridad, una unidad de medida muy útil para evaluar la concentración de las soluciones. Sin embargo, la molaridad es solo una medida de la concentración. Esta sección describirá algunas otras unidades de concentración que se utilizan comúnmente en varias aplicaciones, ya sea por conveniencia o por convención.
### Porcentaje de masa
Anteriormente en este capítulo, se introdujo la composición porcentual como una medida de la cantidad relativa de un elemento determinado en un compuesto. Los porcentajes también se utilizan habitualmente para expresar la composición de las mezclas, incluidas las soluciones. El porcentaje de masa de un componente de la solución se define como la relación entre la masa del componente y la masa de la solución, expresada en porcentaje:
El porcentaje de masa también recibe nombres similares, como tanto por ciento en masa, porcentaje de peso, porcentaje de peso/peso, y otras variaciones sobre este tema. El símbolo más común para el porcentaje de masa es simplemente el signo de porcentaje, %, aunque a menudo se utilizan símbolos más detallados cómo %masa, %peso y (p/p)%. El uso de estos símbolos más detallados puede evitar la confusión de los porcentajes de masa con otros tipos de porcentajes, como los porcentajes de volumen (que se tratarán más adelante en esta sección).
Los porcentajes de masa son unidades de concentración populares para los productos de consumo. La etiqueta de una botella típica de blanqueador líquido () indica que la concentración de su ingrediente activo, el hipoclorito de sodio (NaOCl), es del 7,4 %. Por lo tanto, una muestra de 100,0 g de blanqueador debería contener 7,4 g de NaOCl
### Porcentaje de volumen
Los volúmenes de líquidos en una amplia gama de magnitudes se miden de forma conveniente utilizando equipos de laboratorio comunes y relativamente baratos. Por lo tanto, la concentración de una solución formada por la disolución de un soluto líquido en un disolvente líquido suele expresarse como un porcentaje de volumen, %vol o (v/v)%:
### Porcentaje de masa volumen
Las unidades porcentuales "mixtas", derivadas de la masa del soluto y el volumen de la solución, son populares para ciertas aplicaciones bioquímicas y médicas. Un porcentaje de masa volumen es una relación entre la masa de un soluto y el volumen de la solución, expresada en forma de porcentaje. Las unidades específicas utilizadas para la masa del soluto y el volumen de la solución pueden variar, dependiendo de la solución. Por ejemplo, la solución salina fisiológica, utilizada para preparar fluidos intravenosos, tiene una concentración de 0,9 % masa/volumen (m/v), lo que indica que la composición es de 0,9 g de soluto por 100 mL de solución. La concentración de glucosa en la sangre (comúnmente denominada "azúcar en la sangre") también suele expresarse en términos de una relación masa volumen. Aunque no se exprese explícitamente en porcentaje, su concentración suele darse en miligramos de glucosa por decilitro (100 mL) de sangre ().
### Partes por millón y partes por mil millones
Las concentraciones de solutos muy bajas se expresan a menudo utilizando unidades adecuadamente pequeñas, como partes por millón (ppm) o partes por mil millones (ppb). Al igual que las unidades de porcentaje ("parte por cien"), las ppm y las ppb pueden definirse en términos de masas, volúmenes o unidades mixtas de masa y volumen. También hay unidades de ppm y ppb definidas con respecto al número de átomos y moléculas.
A continuación, se dan las definiciones de ppm y ppb basadas en la masa:
Tanto las ppm como las ppb son unidades convenientes para informar las concentraciones de contaminantes y de otros contaminantes en trazas en el agua. Las concentraciones de estos contaminantes suelen ser muy bajas en las aguas tratadas y naturales, y sus niveles no pueden superar los umbrales de concentración relativamente bajos sin causar efectos adversos en la salud y la fauna. Por ejemplo, la EPA ha determinado que el nivel máximo seguro de iones de flúor en el agua del grifo es de 4 ppm. Los filtros de agua en línea están diseñados para reducir la concentración de flúor y otros contaminantes del agua del grifo ().
### Resumen de la sección
Además de la molaridad, se utilizan otras unidades de concentración de soluciones en diversas aplicaciones. Las concentraciones porcentuales basadas en las masas de los componentes de la solución, los volúmenes o ambos son útiles para expresar concentraciones relativamente altas, mientras que las concentraciones más bajas se expresan convenientemente utilizando unidades de ppm o ppb. Estas unidades son populares en los campos del medio ambiente, la medicina y otros en los que las unidades basadas en el mol, como la molaridad, no se utilizan con tanta frecuencia.
### Ecuaciones clave
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# Estequiometría de las reacciones químicas
## Introducción
Los cohetes de combustible sólido son un elemento central en los programas de exploración espacial del mundo, incluido el nuevo Sistema de Lanzamiento Espacial que está desarrollando la Administración Nacional de Aeronáutica y del Espacio (NASA) para sustituir a la flota de transbordadores espaciales retirados (). Los motores de estos cohetes se basan en mezclas sólidas de sustancias químicas cuidadosamente preparadas y combinadas en cantidades exactamente medidas. Al encender la mezcla, se inicia una vigorosa reacción química que genera rápidamente grandes cantidades de productos gaseosos. Estos gases son expulsados del motor del cohete a través de su tobera, proporcionando el empuje necesario para propulsar cargas pesadas al espacio. Tanto la naturaleza de esta reacción química, como las relaciones entre las cantidades de las sustancias consumidas y producidas por la reacción, son consideraciones de importancia crítica que determinan el éxito de la tecnología. Este capítulo describirá cómo simbolizar las reacciones químicas utilizando ecuaciones químicas, cómo clasificar algunas reacciones químicas comunes identificando patrones de reactividad y cómo determinar las relaciones cuantitativas entre las cantidades de sustancias que intervienen en las reacciones químicas, es decir, la estequiometría de la reacción. |
# Estequiometría de las reacciones químicas
## Escritura y balance de ecuaciones químicas
En un capítulo anterior de este texto se introdujo el uso de símbolos de elementos para representar átomos individuales. Cuando los átomos ganan o pierden electrones para dar lugar a iones, o se combinan con otros átomos para formar moléculas, sus símbolos se modifican o combinan para generar fórmulas químicas que representen adecuadamente estas especies. La extensión de este simbolismo para representar tanto las identidades como las cantidades relativas de las sustancias que sufren un cambio químico (o físico) implica escribir y equilibrar una ecuación química. Consideremos como ejemplo la reacción entre una molécula de metano (CH4) y dos moléculas de oxígeno diatómico (O2) para producir una molécula de dióxido de carbono (CO2) y dos moléculas de agua (H2O). La ecuación química que representa este proceso aparece en la mitad superior de la , con modelos moleculares de espacio lleno en la mitad inferior de la figura.
Este ejemplo ilustra los aspectos fundamentales de cualquier ecuación química:
1. Las sustancias que reaccionan se llaman reactivos y sus fórmulas se colocan en el lado izquierdo de la ecuación.
2. Las sustancias generadas por la reacción se llaman productos, y sus fórmulas se colocan en el lado derecho de la ecuación.
3. Los signos más (+) separan las fórmulas individuales del reactivo y del producto, y una flecha separa los lados del reactivo y del producto (izquierda y derecha) de la ecuación.
4. Los números relativos de las especies de reactivos y productos están representados por coeficientes (números colocados inmediatamente a la izquierda de cada fórmula). Un coeficiente de 1 se suele omitir.
Es una práctica común utilizar los coeficientes de números enteros más pequeños posibles en una ecuación química, como se hace en este ejemplo. Sin embargo, hay que tener en cuenta que estos coeficientes representan los números relativos de reactivos y productos y, por lo tanto, pueden interpretarse correctamente como cocientes. El metano y el oxígeno reaccionan para producir dióxido de carbono y agua en un cociente de 1:2:1:2. Este cociente se cumple si los números de estas moléculas son, respectivamente, 1-2-1-2, o 2-4-2-4, o 3-6-3-6, y así sucesivamente (). Así mismo, estos coeficientes pueden interpretarse con respecto a cualquier unidad de cantidad (número), por lo que esta ecuación puede leerse correctamente de muchas maneras, entre ellas:
1. Una molécula de metano y dos de oxígeno reaccionan para dar lugar a una molécula de dióxido de carbono y dos de agua.
2. Una docena de moléculas de metano y dos docenas de moléculas de oxígeno reaccionan para producir una docena de moléculas de dióxido de carbono y dos docenas de moléculas de agua.
3. Un mol de moléculas de metano y 2 moles de moléculas de oxígeno reaccionan para producir 1 mol de moléculas de dióxido de carbono y 2 moles de moléculas de agua.
### Balance de ecuaciones
La ecuación química descrita en el apartado 4.1 está balanceada, lo que significa que en los lados del reactivo y del producto se representan números iguales de átomos de cada elemento que interviene en la reacción. Este es un requisito que la ecuación debe satisfacer para ser consistente con la ley de conservación de la materia. Se puede confirmar simplemente sumando los números de átomos a cada lado de la flecha y comparando estas sumas para asegurarse de que son iguales. Tenga en cuenta que el número de átomos de un elemento determinado se calcula multiplicando el coeficiente de cualquier fórmula que contenga ese elemento por el subíndice del elemento en la fórmula. Si un elemento aparece en más de una fórmula en un lado determinado de la ecuación, hay que calcular el número de átomos representados en cada una y luego sumarlos. Por ejemplo, ambas especies de productos en la reacción de ejemplo, CO2 y H2O, contienen el elemento oxígeno, por lo que el número de átomos de oxígeno en el lado del producto de la ecuación es
Se confirma que la ecuación de la reacción entre el metano y el oxígeno para producir dióxido de carbono y agua está balanceada según este enfoque, como se muestra aquí:
Una ecuación química balanceada a menudo puede derivarse de una descripción cualitativa de alguna reacción química mediante un enfoque bastante simple conocido como balance por inspección. Consideremos como ejemplo la descomposición del agua para producir hidrógeno y oxígeno moleculares. Este proceso se representa cualitativamente mediante una ecuación química desbalanceada:
La comparación del número de átomos de H y O en cada lado de esta ecuación confirma su desbalance:
Los números de átomos de H en los lados del reactivo y del producto de la ecuación son iguales, pero los números de átomos de O no lo son. Para lograr el balance, los coeficientes de la ecuación pueden modificarse según sea necesario. Hay que tener en cuenta, por supuesto, que los subíndices de la fórmula definen, en parte, la identidad de la sustancia, por lo que no se pueden cambiar sin alterar el significado cualitativo de la ecuación. Por ejemplo, si se cambia la fórmula del reactivo de H2O a H2O2, se balancea el número de átomos, pero al hacerlo también cambia la identidad del reactivo (ahora es peróxido de hidrógeno y no agua). El balance del átomo de O puede lograrse cambiando el coeficiente del H2O a 2.
El balance de los átomos de H se vio alterado por este cambio, pero se restablece fácilmente cambiando el coeficiente del producto H2 a 2.
Estos coeficientes dan lugar a un número igual de átomos de H y O en los lados del reactivo y del producto, y la ecuación balanceada es, por tanto:
A veces es conveniente utilizar fracciones en lugar de números enteros como coeficientes intermedios en el proceso de balancear una ecuación química. Cuando se consigue el balance, todos los coeficientes de la ecuación pueden multiplicarse por un número entero para convertir los coeficientes fraccionarios en enteros sin alterar el balance de los átomos. Por ejemplo, considere la reacción del etano (C2H6) con el oxígeno para producir H2O y CO2, representada por la ecuación desbalanceada:
Siguiendo el enfoque habitual de inspección, se podrían primero balancear los átomos de C y H cambiando los coeficientes para las dos especies del producto, como se muestra:
Esto da como resultado siete átomos de O en el lado del producto de la ecuación, un número impar, no se puede utilizar un coeficiente entero con el reactivo O2 para obtener un número impar, así que un coeficiente fraccionario, para obtener una ecuación balanceada provisional:
Una ecuación balanceada convencional con coeficientes solo enteros se obtiene multiplicando cada coeficiente por 2:
Por último, con respecto a las ecuaciones balanceadas, recuerde que la convención dicta el uso de los coeficientes de números enteros más pequeños. Aunque la ecuación de la reacción entre el nitrógeno molecular y el hidrógeno molecular para producir amoníaco está, efectivamente, balanceada,
los coeficientes no son los números enteros más pequeños posibles que representan los números relativos de las moléculas del reactivo y del producto. Dividiendo cada coeficiente entre el máximo común divisor, 3, se obtiene la ecuación preferida:
### Información adicional en las ecuaciones químicas
Los estados físicos de los reactivos y productos en las ecuaciones químicas se indican muy a menudo con una abreviatura entre paréntesis a continuación de las fórmulas. Las abreviaturas más comunes son s para los sólidos, l para los líquidos, g para los gases y aq para las sustancias disueltas en agua (soluciones acuosas, como se presentó en el capítulo anterior). Estas anotaciones se ilustran en la ecuación de ejemplo:
Esta ecuación representa la reacción que tiene lugar cuando el sodio metálico se coloca en el agua. El sodio sólido reacciona con el agua líquida para producir gas hidrógeno molecular y el compuesto iónico hidróxido de sodio (un sólido en estado puro, pero que se disuelve fácilmente en agua).
Las condiciones especiales necesarias para una reacción se designan a veces escribiendo una palabra o un símbolo encima o debajo de la flecha de la ecuación. Por ejemplo, una reacción realizada por calentamiento puede indicarse con la letra griega mayúscula delta (Δ) sobre la flecha.
Otros ejemplos de estas condiciones especiales se encuentran en mayor profundidad en capítulos posteriores.
### Ecuaciones de las reacciones iónicas
Dada la abundancia de agua en la Tierra, es lógico que un gran número de reacciones químicas tengan lugar en medios acuosos. Cuando los iones intervienen en estas reacciones, las ecuaciones químicas pueden escribirse con varios niveles de detalle adecuados a su uso previsto. Para ilustrar esto, consideremos una reacción entre compuestos iónicos que tiene lugar en una solución acuosa. Cuando se mezclan soluciones acuosas de CaCl2 y AgNO3, se produce una reacción que produce Ca(NO3)2 acuoso y AgCl sólido:
Esta ecuación balanceada, derivada de la manera habitual, se llama ecuación molecular porque no representa explícitamente las especies iónicas que están presentes en la solución. Cuando los compuestos iónicos se disuelven en agua, pueden disociarse en sus iones constituyentes, que posteriormente se dispersan de forma homogénea por la solución resultante (en el capítulo sobre soluciones se ofrece un análisis exhaustivo de este importante proceso). Por lo tanto, los compuestos iónicos disueltos en el agua se representan de forma más realista como iones disociados, en este caso:
A diferencia de estos tres compuestos iónicos, el AgCl no se disuelve en el agua de forma significativa, como lo indica su notación de estado físico, s.
La representación explícita de todos los iones disueltos da lugar a una ecuación iónica completa. En este caso concreto, las fórmulas de los compuestos iónicos disueltos se sustituyen por fórmulas de sus iones disociados:
El examen de esta ecuación muestra que dos especies químicas están presentes en forma idéntica a ambos lados de la flecha, Ca2+(aq) y Estos iones espectadores, cuya presencia es necesaria para mantener la neutralidad de la carga, no cambian ni química ni físicamente por el proceso, por lo que pueden ser eliminados de la ecuación para obtener una representación más sucinta llamada ecuación iónica neta:
Siguiendo la convención de utilizar los enteros más pequeños posibles como coeficientes, esta ecuación se escribe entonces:
Esta ecuación iónica neta indica que el cloruro de plata sólido puede producirse a partir de iones de cloruro y plata(I) disueltos, independientemente de la fuente de estos iones. Estas ecuaciones moleculares e iónicas completas proporcionan información adicional, a saber, los compuestos iónicos utilizados como fuentes de Cl− y Ag+.
### Conceptos clave y resumen
Las ecuaciones químicas son representaciones simbólicas de los cambios químicos y físicos. Las fórmulas de las sustancias que sufren el cambio (reactivos) y las sustancias generadas por el cambio (productos) están separadas por una flecha y precedidas por coeficientes enteros que indican sus números relativos. Las ecuaciones balanceadas son aquellas cuyos coeficientes dan como resultado un número igual de átomos para cada elemento en los reactivos y productos. Las reacciones químicas en solución acuosa que implican reactivos o productos iónicos pueden representarse de forma más realista mediante ecuaciones iónicas completas y, de forma más sucinta, mediante ecuaciones iónicas netas.
### Ejercicios de química del final del capítulo
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# Estequiometría de las reacciones químicas
## Clasificación de las reacciones químicas
Los seres humanos interactúan entre sí de formas diversas y complejas y clasificamos estas interacciones según patrones comunes de comportamiento. Cuando dos seres humanos intercambian información, decimos que se están comunicando. Cuando intercambian golpes con los puños o con los pies, decimos que están peleando. Ante la gran variedad de interacciones entre sustancias químicas, los científicos también han considerado conveniente (o incluso necesario) clasificar las interacciones químicas identificando patrones comunes de reactividad. Este módulo proporcionará una introducción a tres de los tipos más frecuentes de reacciones químicas: precipitación, ácido-base y oxidación-reducción.
### Reacciones de precipitación y reglas de solubilidad
Una reacción de precipitación es aquella en la que las sustancias disueltas reaccionan para formar uno (o varios) productos sólidos. Muchas reacciones de este tipo implican el intercambio de iones entre compuestos iónicos en solución acuosa y a veces se denominan reacciones de doble desplazamiento, doble sustitución o metátesis. Estas reacciones son comunes en la naturaleza y son responsables de la formación de arrecifes de coral en las aguas oceánicas y de los cálculos renales en los animales. Se utilizan ampliamente en la industria para la producción número de productos químicos básicos y especiales. Las reacciones de precipitación también desempeñan un papel fundamental en muchas técnicas de análisis químico, como las pruebas puntuales utilizadas para identificar los iones metálicos y los métodos gravimétricos para determinar la composición de la materia (vea el último módulo de este capítulo).
El grado en que una sustancia puede disolverse en el agua, o en cualquier solvente, se expresa cuantitativamente como su solubilidad, definida como la concentración máxima de una sustancia que puede alcanzarse en condiciones específicas. Se dice que las sustancias con solubilidades relativamente altas son solubles. Una sustancia se precipitará cuando las condiciones de la solución sean tales que su concentración supere su solubilidad. Se dice que las sustancias con solubilidad relativamente baja son insolubles y son las que se precipitan fácilmente de la solución. En un capítulo posterior sobre soluciones se ofrece más información sobre estos importantes conceptos. Para predecir las identidades de los sólidos formados por las reacciones de precipitación, uno puede simplemente referirse a los patrones de solubilidad que se han observado para muchos compuestos iónicos ().
Un ejemplo claro de precipitación se observa cuando se mezclan soluciones de yoduro de potasio y nitrato de plomo, lo que da lugar a la formación de yoduro de plomo sólido:
Esta observación es coherente con las directrices de solubilidad: El único compuesto insoluble entre todos los implicados es el yoduro de plomo, una de las excepciones a la solubilidad general de las sales de yoduro.
La ecuación iónica neta que representa esta reacción es:
El yoduro de plomo es un sólido de color amarillo brillante que se utilizaba antiguamente como pigmento para artistas, conocido como amarillo de yodo (). Las propiedades de los cristales de PbI2 puro los hacen útiles para la fabricación de detectores de rayos X y gamma.
Las pautas de solubilidad en la pueden utilizarse para predecir si se producirá una reacción de precipitación cuando se mezclen soluciones de compuestos iónicos solubles. Solo hay que identificar todos los iones presentes en la solución y luego considerar si el posible emparejamiento catión/anión podría dar lugar a un compuesto insoluble. Por ejemplo, al mezclar soluciones de nitrato de plata y cloruro de sodio, se producirá una solución que contiene iones de Ag+, iones de Na+ y Cl-. Además de los dos compuestos iónicos presentes originalmente en las soluciones, AgNO3 y NaF, pueden derivarse dos compuestos iónicos adicionales de esta colección de iones: NaNO3 y AgCl. Las directrices de solubilidad indican que todas las sales de nitrato son solubles, pero que el AgCl es uno de los insolubles. Por lo tanto, se prevé que se produzca una reacción de precipitación, tal como se describe en las siguientes ecuaciones:
### Reacciones ácido-base
Una reacción ácido-base es aquella en la que un ion hidrógeno, H+, se transfiere de una especie química a otra. Estas reacciones tienen una importancia fundamental en numerosos procesos naturales y tecnológicos, desde las transformaciones químicas que tienen lugar en el interior de las células y los lagos y océanos, hasta la producción a escala industrial de fertilizantes, productos farmacéuticos y otras sustancias esenciales para la sociedad. El tema de la química ácido-base, por lo tanto, merece una discusión profunda, y se dedica un capítulo completo a este tema más adelante en el texto.
En esta breve introducción, consideraremos solo los tipos más comunes de reacciones ácido-base que tienen lugar en soluciones acuosas. En este contexto, un ácido es una sustancia que se disuelve en el agua para producir iones de hidronio, H3O+. Como ejemplo, considere la ecuación que se muestra aquí:
El proceso representado por esta ecuación confirma que el cloruro de hidrógeno es un ácido. Cuando se disuelve en agua, los iones H3O+ se producen por una reacción química en la que los iones H+ se transfieren de las moléculas de HCl a las de H2O ().
La naturaleza del HCl es tal que su reacción con el agua, tal y como se acaba de describir, es esencialmente eficaz al 100%: Prácticamente todas las moléculas de HCl que se disuelven en el agua sufren esta reacción. Los ácidos que reaccionan completamente de esta manera se llaman ácidos fuertes y el HCl es uno de los pocos compuestos ácidos comunes que se clasifican como fuertes (). Un número mucho mayor de compuestos se comportan como ácidos débiles y solo reaccionan parcialmente con el agua, dejando una gran mayoría de moléculas disueltas en su forma original y generando una cantidad relativamente pequeña de iones de hidronio. Los ácidos débiles son habituales en la naturaleza, ya que son las sustancias responsables, en parte, del sabor ácido de los cítricos, de la sensación de picadura de los insectos y de los olores desagradables asociados al olor corporal. Un ejemplo conocido de ácido débil es el ácido acético, el principal ingrediente de los vinagres alimentarios:
Cuando se disuelve en agua en condiciones típicas, solo alrededor del 1% de las moléculas de ácido acético están presentes en la forma ionizada, (). (El uso de una flecha doble en la ecuación anterior denota el aspecto de reacción parcial de este proceso, un concepto que se aborda completamente en los capítulos sobre el equilibrio químico).
Una base es una sustancia que se disuelve en el agua para producir iones de hidróxido, OH−. Las bases más comunes son compuestos iónicos formados por cationes de metales alcalinos o alcalinotérreos (grupos 1 y 2) combinados con el ion hidróxido; por ejemplo, NaOH y Ca(OH)2. A diferencia de los compuestos ácidos que se han comentado anteriormente, estos compuestos no reaccionan químicamente con el agua, sino que se disuelven y disocian, liberando iones de hidróxido directamente en la solución. Por ejemplo, el KOH y el Ba(OH)2 se disuelven en agua y se disocian completamente para producir cationes (K+ y Ba2+, respectivamente) e iones hidróxido, OH−. Estas bases, junto con otros hidróxidos que se disocian completamente en el agua, se consideran bases fuertes.
Consideremos como ejemplo la disolución de la lejía (hidróxido de sodio) en el agua:
Esta ecuación confirma que el hidróxido de sodio es una base. Cuando está disuelto en agua, el NaOH se disocia para dar lugar a iones Na+ y OH−. Esto también es cierto para cualquier otro compuesto iónico que contenga iones de hidróxido. Dado que el proceso de disociación es esencialmente completo cuando los compuestos iónicos se disuelven en agua en condiciones típicas, el NaOH y otros hidróxidos iónicos se clasifican como bases fuertes.
A diferencia de los hidróxidos iónicos, algunos compuestos producen iones de hidróxido cuando se disuelven al reaccionar químicamente con las moléculas de agua. En todos los casos, estos compuestos reaccionan solo parcialmente, por lo que se clasifican como bases débiles. Estos tipos de compuestos también son abundantes en la naturaleza y productos importantes en diversas tecnologías. Por ejemplo, la producción mundial de amoníaco de base débil suele superar las 100 toneladas métricas anuales, siendo ampliamente utilizado como fertilizante agrícola, materia prima para la síntesis química de otros compuestos y como ingrediente activo en los limpiadores domésticos (). Cuando se disuelve en agua, el amoníaco reacciona parcialmente para dar lugar a iones de hidróxido, como se muestra aquí:
Se trata, por definición, de una reacción ácido-base, que en este caso implica la transferencia de iones H+ de las moléculas de agua a las de amoníaco. En condiciones normales, solo un 1% del amoníaco disuelto está presente como iones de .
Una reacción de neutralización es un tipo específico de reacción ácido-base en la que los reactivos son un ácido y una base (pero no agua), y los productos suelen ser una sal y agua
Para ilustrar una reacción de neutralización, consideremos lo que ocurre cuando se ingiere un antiácido típico como la leche de magnesia (una suspensión acuosa de Mg(OH)2 sólido) para aliviar los síntomas asociados al exceso de ácido estomacal (HCl):
Observe que, además de agua, esta reacción produce una sal, el cloruro de magnesio.
### Reacciones de oxidación-reducción
La atmósfera de la Tierra contiene aproximadamente un 20 % de oxígeno molecular, O2, un gas químicamente reactivo que desempeña un papel esencial en el metabolismo de los organismos aeróbicos y en muchos procesos medioambientales que dan forma al mundo. El término oxidación se utilizaba originalmente para describir las reacciones químicas en las que intervenía el O2, pero su significado ha evolucionado para referirse a una amplia e importante clase de reacción conocida como reacciones de oxidación-reducción (redox). Se utilizarán algunos ejemplos de estas reacciones para desarrollar una imagen clara de esta clasificación.
Algunas reacciones redox implican la transferencia de electrones entre especies reaccionantes para obtener productos iónicos, como la reacción entre el sodio y el cloro para obtener cloruro de sodio:
Es útil ver el proceso con respecto a cada reactivo individual, es decir, representar el destino de cada reactivo en forma de una ecuación llamada media reacción:
Estas ecuaciones muestran que los átomos de Na pierden electrones mientras que los átomos de Cl (en la molécula de Cl2) ganan electrones, los subíndices "s" para los iones resultantes significan que están presentes en forma de un compuesto iónico sólido. En este tipo de reacciones redox, la pérdida y la ganancia de electrones definen los procesos complementarios que se producen:
En esta reacción, pues, el sodio se oxida y el cloro se reduce. Visto desde una perspectiva más activa, el sodio funciona como un agente reductor (reductor), ya que proporciona electrones al cloro (o lo reduce). Así mismo, el cloro funciona como agente oxidante (oxidante), ya que elimina eficazmente los electrones del sodio (lo oxida).
Sin embargo, algunos procesos redox no implican la transferencia de electrones. Consideremos, por ejemplo, una reacción similar a la que produce el NaCl:
El producto de esta reacción es un compuesto covalente, por lo que no hay transferencia de electrones en el sentido explícito. Para aclarar la similitud de esta reacción con la anterior y permitir una definición inequívoca de las reacciones redox, se ha definido una propiedad denominada número de oxidación. El número de oxidación (o estado de oxidación) de un elemento en un compuesto es la carga que poseerían sus átomos si el compuesto fuera iónico. Para asignar los números de oxidación a cada elemento de una molécula o un ion se utilizan las siguientes directrices.
1. El número de oxidación de un átomo en una sustancia elemental es cero.
2. El número de oxidación de un ion monatómico es igual a la carga del ion.
3. Los números de oxidación de los no-metales comunes se suelen asignar de la siguiente manera:
4. La suma de los números de oxidación de todos los átomos de una molécula o ion poliatómico es igual a la carga de la molécula o ion.
Nota: La convención adecuada para informar de la carga es escribir primero el número, seguido del signo (por ejemplo, 2+), mientras que el número de oxidación se escribe con la secuencia inversa, signo seguido de número (por ejemplo, +2). Esta convención pretende destacar la distinción entre estas dos propiedades relacionadas.
Utilizando el concepto de número de oxidación, se ha establecido una definición global de reacción redox. Las reacciones de reducción-oxidación (redox) son aquellas en las que uno o varios elementos implicados sufren un cambio de número de oxidación. (Aunque la gran mayoría de las reacciones redox implican cambios en el número de oxidación de dos o más elementos, existen algunas excepciones interesantes a esta regla: .) Las definiciones de los procesos complementarios de esta clase de reacción se revisan correspondientemente, como se muestra aquí:
Volviendo a las reacciones utilizadas para introducir este tema, ambas pueden identificarse ahora como procesos redox. En la reacción entre el sodio y el cloro para producir cloruro de sodio, el sodio se oxida (su número de oxidación aumenta de 0 en Na a +1 en NaCl) y el cloro se reduce (su número de oxidación disminuye de 0 en Cl2 a -1 en NaCl). En la reacción entre el hidrógeno molecular y el cloro, el hidrógeno se oxida (su número de oxidación aumenta de 0 en H2 a +1 en HCl) y el cloro se reduce (su número de oxidación disminuye de 0 en Cl2 a −1 en HCl).
Se reconocen varias subclases de reacciones redox, incluidas las reacciones de combustión en las que el reductor (también llamado combustible) y el oxidante (a menudo, pero no necesariamente, oxígeno molecular) reaccionan vigorosamente y producen cantidades significativas de calor, y a menudo luz, en forma de llama. Las reacciones de los combustibles sólidos para cohetes, como la representada en la , son procesos de combustión. Una reacción típica de propulsión en la que el aluminio sólido es oxidado por el perclorato de amonio está representada por esta ecuación:
Las reacciones de desplazamiento único (reemplazo) son reacciones redox en las que un ion en solución es desplazado (o reemplazada) mediante la oxidación de un elemento metálico. Un ejemplo común de este tipo de reacción es la oxidación ácida de ciertos metales:
Los elementos metálicos también pueden ser oxidados por soluciones de otras sales metálicas; por ejemplo:
Esta reacción puede observarse colocando un hilo de cobre en una solución que contenga una sal de plata disuelta. Los iones de plata en solución se reducen a plata elemental en la superficie del alambre de cobre, y los iones Cu2+ resultantes se disuelven en la solución para producir un color azul característico ().
### Balance de las reacciones redox por el método de la media reacción
Las reacciones redox que tienen lugar en medios acuosos suelen incluir agua, iones de hidronio e iones de hidróxido como reactivos o productos. Aunque estas especies no se oxidan ni se reducen, participan en el cambio químico de otras maneras (por ejemplo, proporcionando los elementos necesarios para formar oxianiones). Las ecuaciones que representan estas reacciones son a veces muy difíciles de balancear por inspección, por lo que se han desarrollado enfoques sistemáticos para ayudar en el proceso. Un enfoque muy útil es utilizar el método de las semirreacciones, que implica los siguientes pasos:
1. Escriba las dos semirreacciones que representan el proceso redox.
2. Balancee todos los elementos excepto el oxígeno y el hidrógeno.
3. Balancee los átomos de oxígeno añadiendo moléculas de H2O.
4. Balancee los átomos de hidrógeno añadiendo iones H+.
5. Balancee la carga añadiendo electrones.
6. Si es necesario, multiplique los coeficientes de cada semirreacción por los números enteros más pequeños posibles para obtener un número igual de electrones en cada uno.
7. Sume las semirreacciones balanceadas y simplifique eliminando las especies que aparecen en ambos lados de la ecuación.
8. Para las reacciones que se producen en medios básicos (exceso de iones hidróxido), realice estos pasos adicionales:
1. Añada iones OH− a ambos lados de la ecuación en número igual al de los iones H+.
2. En el lado de la ecuación que contiene los iones H+ y OH−, combine estos iones para obtener moléculas de agua.
3. Simplifique la ecuación eliminando las moléculas de agua redundantes.
9. Por último, compruebe que tanto el número de átomos como las cargas totalesEl requisito de "balance de carga" es solo un tipo específico de "balance de masa" en el que las especies en cuestión son los electrones. Una ecuación debe representar igual número de electrones en el lado del reactivo y del producto, por lo que tanto los átomos como las cargas deben estar balanceados. están balanceados.
### Conceptos clave y resumen
Las reacciones químicas se clasifican según patrones de comportamiento similares. Un gran número de reacciones importantes se incluyen en tres categorías: precipitación, ácido-base y oxidación-reducción (redox). Las reacción de precipitación implican la formación de uno o más productos insolubles. Las reacciones ácido-base implican la transferencia de iones de hidrógeno entre los reactivos. Las reacciones redox implican un cambio en el número de oxidación de uno o más elementos reactivos. La escritura de ecuaciones balanceadas para algunas reacciones redox que ocurren en soluciones acuosas se simplifica utilizando un enfoque sistemático llamado método de la media reacción.
### Ejercicios de química del final del capítulo
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# Estequiometría de las reacciones químicas
## Estequiometría de la reacción
Una ecuación química balanceada proporciona una gran cantidad de información en un formato muy sucinto. Las fórmulas químicas proporcionan las identidades de los reactivos y los productos que intervienen en el cambio químico, lo que permite clasificar la reacción. Los coeficientes proporcionan los números relativos de estas especies químicas, permitiendo una evaluación cuantitativa de las relaciones entre las cantidades de sustancias consumidas y producidas por la reacción. Estas relaciones cuantitativas se conocen como estequiometría de la reacción, término derivado de las palabras griegas stoicheion (que significa "elemento") y metron (que significa "medida"). En este módulo se explora el uso de ecuaciones químicas balanceadas para diversas aplicaciones estequiométricas.
El enfoque general para utilizar las relaciones estequiométricas es similar en concepto a la forma en que la gente realiza muchas actividades comunes. La preparación de alimentos, por ejemplo, ofrece una comparación adecuada. Una receta para hacer ocho panqueques requiere 1 taza de mezcla para panqueques, taza de leche, y un huevo. La "ecuación" que representa la preparación de los panqueques según esta receta es
Si se necesitan dos docenas de panqueques para un desayuno familiar numeroso, las cantidades de ingredientes deben aumentarse proporcionalmente según las cantidades indicadas en la receta. Por ejemplo, el número de huevos necesarios para hacer 24 panqueques es
Las ecuaciones químicas balanceadas se utilizan de forma muy similar para determinar la cantidad de un reactivo necesaria para reaccionar con una cantidad determinada de otro reactivo, o para obtener una cantidad determinada de producto, etc. Los coeficientes de la ecuación balanceada se utilizan para obtener los factores estequiométricos que permiten calcular la cantidad deseada. Para ilustrar esta idea, consideremos la producción de amoníaco por reacción de hidrógeno y nitrógeno:
Esta ecuación muestra que las moléculas de amoníaco se producen a partir de moléculas de hidrógeno en un cociente de 2:3 y los factores estequiométricos pueden derivarse utilizando cualquier unidad de cantidad (número):
Estos factores estequiométricos pueden utilizarse para calcular el número de moléculas de amoníaco producidas a partir de un número determinado de moléculas de hidrógeno, o el número de moléculas de hidrógeno necesarias para producir un número determinado de moléculas de amoníaco. Se pueden derivar factores similares para cualquier par de sustancias en cualquier ecuación química.
Estos ejemplos ilustran la facilidad con la que se pueden relacionar las cantidades de sustancias que intervienen en una reacción química de estequiometría conocida. Sin embargo, medir directamente el número de átomos y moléculas no es una tarea fácil, y la aplicación práctica de la estequiometría requiere que utilicemos la propiedad de la masa, más fácil de medir.
Estos ejemplos ilustran solo algunos casos de cálculos de estequiometría de reacción. Son posibles numerosas variaciones en los pasos computacionales iniciales y finales, dependiendo de las cantidades particulares que se proporcionen y busquen (volúmenes, concentraciones de la solución, etc.). Independientemente de los detalles, todos estos cálculos comparten un componente esencial común: el uso de factores estequiométricos derivados de ecuaciones químicas balanceadas. La proporciona un esquema general de los diversos pasos computacionales asociados a muchos cálculos de estequiometría de reacciones.
### Conceptos clave y resumen
Una ecuación química balanceada puede utilizarse para describir la estequiometría de una reacción (las relaciones entre las cantidades de reactivos y productos). Los coeficientes de la ecuación se utilizan para derivar los factores estequiométricos que posteriormente pueden utilizarse para los cálculos que relacionan las masas de los reactivos y los productos, las cantidades molares y otras propiedades cuantitativas.
### Ejercicios de química del final del capítulo
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# Estequiometría de las reacciones químicas
## Rendimiento de la reacción
Las cantidades relativas de reactivos y productos representadas en una ecuación química balanceada suelen denominarse cantidades estequiométricas. Todos los ejercicios del módulo anterior incluían cantidades estequiométricas de reactivos. Por ejemplo, al calcular la cantidad de producto generado a partir de una determinada cantidad de reactivo, se asumió que cualquier otro reactivo necesario estaba disponible en cantidades estequiométricas (o mayores). En este módulo se consideran situaciones más realistas, en las que los reactivos no están presentes en cantidades estequiométricas.
### Reactivo limitante
Consideremos otra analogía alimenticia, la preparación de sándwiches de queso a la parrilla ():
Las cantidades estequiométricas de los ingredientes del sándwich para esta receta son pan y rebanadas de queso en un cociente de 2:1. Si se dispone de 28 rebanadas de pan y 11 rebanadas de queso, se pueden preparar 11 sándwiches de acuerdo con la receta proporcionada, utilizando todo el queso proporcionado y sobrándole seis rebanadas de pan. En este escenario, el número de sándwiches preparados ha sido limitado por el número de rebanadas de queso, y las rebanadas de pan se han proporcionado en exceso.
Consideremos ahora este concepto con respecto a un proceso químico, la reacción del hidrógeno con el cloro para producir cloruro de hidrógeno:
La ecuación balanceada muestra que el hidrógeno y el cloro reaccionan en un cociente estequiométrico de 1:1. Si estos reactivos se suministran en cualquier otra cantidad, uno de los reactivos se consumirá casi siempre por completo, limitando así la cantidad de producto que puede generarse. Esta sustancia es el reactivo limitante, y la otra sustancia es el exceso de reactivo. La identificación de los reactivos limitantes y en exceso de reactivo para una situación dada requiere el cálculo de las cantidades molares de cada reactivo proporcionado y su comparación con las cantidades estequiométricas representadas en la ecuación química balanceada. Por ejemplo, imagine que combina 3 moles de H2 y 2 moles de Cl2. Esto representa un cociente 3:2 (o 1,5:1) entre el hidrógeno y el cloro presentes para la reacción, que es mayor que el cociente estequiométrico de 1:1. Por lo tanto, el hidrógeno está presente en exceso y el cloro es el reactivo limitante. La reacción de todo el cloro proporcionado (2 mol) consumirá 2 mol de los 3 mol de hidrógeno proporcionados, dejando 1 mol de hidrógeno sin reaccionar.
Un enfoque alternativo para identificar el reactivo limitante consiste en comparar la cantidad de producto esperada para la reacción completa de cada reactivo. Cada cantidad de reactivo se utiliza para calcular por separado la cantidad de producto que se formaría según la estequiometría de la reacción. El reactivo que da la menor cantidad de producto es el reactivo limitante. Para el ejemplo del párrafo anterior, la reacción completa del hidrógeno produciría
La reacción completa del cloro suministrado produciría
El cloro se consumirá completamente cuando se hayan producido 4 moles de HCl. Dado que se proporcionó suficiente hidrógeno para producir 6 moles de HCl, habrá hidrógeno sin reaccionar una vez que la reacción se haya completado. Por lo tanto, el cloro es el reactivo limitante y el hidrógeno es el exceso de reactivo ().
### Porcentaje de rendimiento
La cantidad de producto que puede producir una reacción en condiciones específicas, calculada según la estequiometría de una ecuación química balanceada adecuada, se denomina rendimiento teórico de la reacción. En la práctica, la cantidad de producto obtenida se denomina rendimiento real y suele ser inferior al rendimiento teórico por varias razones. Algunas reacciones son intrínsecamente ineficaces, ya que van acompañadas de reacciones secundarias que generan otros productos. Otras son, por naturaleza, incompletas (considere las reacciones parciales de las bases y ácidos débiles que se discutieron anteriormente en este capítulo). Algunos productos son difíciles de recoger sin que se produzcan algunas pérdidas, por lo que una recuperación no perfecta reducirá el rendimiento real. El grado en que se alcanza el rendimiento teórico de una reacción se suele expresar como su porcentaje de rendimiento:
Los rendimientos reales y teóricos pueden expresarse como masas o cantidades molares (o cualquier otra propiedad apropiada; por ejemplo, el volumen, si el producto es un gas). Siempre que ambos rendimientos se expresen con las mismas unidades, estas se cancelarán cuando se calcule el porcentaje de rendimiento.
### Conceptos clave y resumen
Cuando las reacciones se llevan a cabo utilizando cantidades de reactivos inferiores a las estequiométricas, la cantidad de producto generado vendrá determinada por el reactivo limitante. La cantidad de producto generado por una reacción química es su rendimiento real. Este rendimiento suele ser inferior a la cantidad de producto prevista por la estequiometría de la ecuación química balanceada que representa la reacción (su rendimiento teórico). El grado en que una reacción genera la cantidad teórica de producto se expresa como su porcentaje de rendimiento.
### Ecuaciones clave
### Ejercicios de química del final del capítulo
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# Estequiometría de las reacciones químicas
## Análisis químico cuantitativo
En el siglo XVIII, la fuerza (en realidad la concentración) de las muestras de vinagre se determinaba anotando la cantidad de carbonato de potasio, K2CO3, que había que añadir, poco a poco, antes de que cesara el burbujeo. Cuanto mayor sea el peso de carbonato de potasio que se añada para alcanzar el punto en el que termina el burbujeo, más concentrado estará el vinagre.
Ahora sabemos que la efervescencia que se producía durante este proceso se debía a la reacción con el ácido acético, CH3CO2H, el compuesto principalmente responsable del olor y el sabor del vinagre. El ácido acético reacciona con el carbonato de potasio según la siguiente ecuación:
El burbujeo se debe a la producción de CO2.
La prueba del vinagre con carbonato de potasio es un tipo de análisis cuantitativo: la determinación de la cantidad o concentración de una sustancia en una muestra. En el análisis del vinagre, la concentración del soluto (ácido acético) se determinó a partir de la cantidad de reactivo que se combinó con el soluto presente en un volumen conocido de la solución. En otros tipos de análisis químicos, la cantidad de una sustancia presente en una muestra se determina midiendo la cantidad de producto resultante.
### Titulación
El método descrito para medir la fuerza del vinagre era una versión temprana de la técnica analítica conocida como análisis de titulación. Un análisis de titulación típico implica el uso de una bureta () para realizar adiciones incrementales de una solución que contiene una concentración conocida de alguna sustancia (el titulante) a una solución de muestra que contiene la sustancia cuya concentración se va a medir (el analito). El titulante y el analito experimentan una reacción química de estequiometría conocida, por lo que la medición del volumen de solución titulante necesario para la reacción completa con el analito (el punto de equivalencia de la titulación) permite calcular la concentración del analito. El punto de equivalencia de una titulación puede detectarse visualmente si un cambio claro en el aspecto de la solución de la muestra acompaña la finalización de la reacción. La detención de la formación de burbujas en el análisis clásico del vinagre es un ejemplo de ello, aunque, más comúnmente, se añaden tintes especiales llamados indicadores a las soluciones de la muestra para impartir un cambio de color en el punto de equivalencia de la titulación o muy cerca de él. Los puntos de equivalencia también pueden detectarse midiendo alguna propiedad de la solución que cambie de forma predecible durante el curso de la titulación. Independientemente del enfoque adoptado para detectar el punto de equivalencia de una titulación, el volumen de titulante realmente medido se denomina punto final. Los métodos de titulación correctamente diseñados suelen garantizar que la diferencia entre los puntos de equivalencia y final sea insignificante. Aunque cualquier tipo de reacción química puede servir de base para un análisis de titulación, las tres descritas en este capítulo (precipitación, ácido-base y redox) son las más comunes. En el capítulo sobre el equilibrio ácido-base se ofrecen más detalles sobre el análisis de titulación.
### Análisis gravimétrico
Un análisis gravimétrico es aquel en el que una muestra se somete a algún tratamiento que provoca un cambio en el estado físico del analito que permite su separación de los demás componentes de la muestra. Las mediciones de masa de la muestra, del analito aislado o de algún otro componente del sistema de análisis, utilizadas junto con la estequiometría conocida de los compuestos implicados, permiten calcular la concentración del analito. Los métodos gravimétricos fueron las primeras técnicas utilizadas para el análisis químico cuantitativo, y siguen siendo herramientas importantes en el laboratorio de química moderno.
El cambio de estado requerido en un análisis gravimétrico puede lograrse mediante diversos procesos físicos y químicos. Por ejemplo, el contenido de humedad (agua) de una muestra se determina rutinariamente midiendo la masa de una muestra antes y después de someterla a un proceso de calentamiento controlado que evapora el agua. También son comunes las técnicas gravimétricas en las que el analito se somete a una reacción de precipitación del tipo descrito anteriormente en este capítulo. El precipitado se suele aislar de la mezcla de reacción por filtración, se seca cuidadosamente y se pesa (). La masa del precipitado puede utilizarse entonces, junto con las relaciones estequiométricas pertinentes, para calcular la concentración del analito.
La composición elemental de los hidrocarburos y compuestos relacionados puede determinarse mediante un método gravimétrico conocido como análisis de combustión. En un análisis de combustión, una muestra pesada del compuesto se calienta a una temperatura elevada bajo una corriente de gas oxígeno, lo que provoca su combustión completa para obtener productos gaseosos de identidades conocidas. La combustión completa de los hidrocarburos, por ejemplo, dará como únicos productos el dióxido de carbono y el agua. Los productos de la combustión gaseosa se barren a través de dispositivos de recogida separados y previamente pesados que contienen compuestos que absorben selectivamente cada producto (). El aumento de masa de cada dispositivo corresponde a la masa del producto absorbido y puede utilizarse en un cálculo estequiométrico adecuado para obtener la masa del elemento correspondiente.
### Conceptos clave y resumen
La estequiometría de las reacciones químicas puede servir de base para los métodos de análisis químico cuantitativo. Las titulaciones implican la medición del volumen de una solución titulante necesaria para reaccionar completamente con una solución de muestra. Este volumen se utiliza entonces para calcular la concentración de analito en la muestra utilizando la estequiometría de la reacción de titulación. El análisis gravimétrico consiste en separar el analito de la muestra mediante un proceso físico o químico, determinar su masa y, a continuación, calcular su concentración en la muestra en función de la estequiometría del proceso correspondiente. El análisis de combustión es un método gravimétrico utilizado para determinar la composición elemental de un compuesto recogiendo y pesando los productos gaseosos de su combustión.
### Ejercicios de química del final del capítulo
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# Termoquímica
## Introducción
Las reacciones químicas, como las que se producen al encender el fósforo, implican cambios tanto de energía como de materia. Las sociedades de todos los niveles de desarrollo no podrían funcionar sin la energía liberada por las reacciones químicas. En 2012, cerca del 85 % del consumo energético de los Estados Unidos procedía de la combustión de productos petrolíferos, carbón, madera y basura. Utilizamos esta energía para producir electricidad (38 %); para transportar alimentos, materias primas, productos manufacturados y personas (27 %); para la producción industrial (21 %); y para calentar y alimentar nuestros hogares y empresas (10 %).Administración de Información Energética de los EE. UU., Si bien estas reacciones de combustión nos ayudan a satisfacer nuestras necesidades energéticas esenciales, la mayoría de la comunidad científica las reconoce asimismo como una de las causas principales del cambio climático global.
También existen formas útiles de energía a partir de diversas reacciones químicas distintas de la combustión. Por ejemplo, la energía producida por las baterías de un teléfono móvil, un auto o una linterna es el resultado de reacciones químicas. Este capítulo presenta muchas de las ideas básicas necesarias para explorar las relaciones entre los cambios químicos y la energía, centrándose en la energía térmica. |
# Termoquímica
## Conceptos básicos de energía
Los cambios químicos y los cambios de energía que los acompañan son partes importantes de nuestro mundo cotidiano (). Los macronutrientes de los alimentos (proteínas, grasas y carbohidratos) sufren reacciones metabólicas que proporcionan la energía necesaria para que nuestro cuerpo funcione. Quemamos diversos combustibles (gasolina, gas natural, carbón) para producir energía para el transporte, la calefacción y la generación de electricidad. Las reacciones químicas industriales utilizan enormes cantidades de energía para producir materias primas (como el hierro y el aluminio). La energía se utiliza entonces para fabricar esas materias primas en productos útiles, como automóviles, rascacielos y puentes.
Más del 90% de la energía que utilizamos procede del Sol. Diariamente, el Sol envía a la Tierra casi 10.000 veces la cantidad de energía necesaria para satisfacer todas las necesidades energéticas del mundo ese día. Nuestro reto es encontrar formas de convertir y almacenar la energía solar entrante para poder utilizarla en reacciones o procesos químicos que sean convenientes y no contaminantes. Las plantas y muchas bacterias captan la energía solar mediante la fotosíntesis. Liberamos la energía almacenada en las plantas cuando quemamos madera o productos vegetales como el etanol. También utilizamos esta energía para alimentar nuestro cuerpo comiendo alimentos que provienen directamente de las plantas o de animales que obtuvieron su energía comiendo plantas. La quema de carbón y petróleo también libera la energía solar almacenada: estos combustibles son materia vegetal y animal fosilizada.
En este capítulo se presentan las ideas básicas de una importante área de la ciencia que se ocupa de la cantidad de calor absorbida o liberada durante los cambios químicos y físicos, un área llamada termoquímica. Los conceptos introducidos en este capítulo se utilizan ampliamente en casi todos los campos científicos y técnicos. Los científicos de la alimentación los utilizan para determinar el contenido energético de los alimentos. Los biólogos estudian la energía de los organismos vivos, como la combustión metabólica del azúcar en dióxido de carbono y agua. Las industrias del petróleo, el gas y el transporte, los proveedores de energías renovables y muchos otros se esfuerzan por encontrar mejores métodos para producir energía para nuestras necesidades comerciales y personales. Los ingenieros se esfuerzan por mejorar la eficiencia energética, encontrar mejores formas de calentar y enfriar nuestros hogares, refrigerar nuestros alimentos y bebidas y satisfacer las necesidades de energía y refrigeración de las computadoras y la electrónica, entre otras aplicaciones. Entender los principios termoquímicos es esencial para químicos, físicos, biólogos, geólogos, todo tipo de ingenieros y casi cualquier persona que estudie o haga cualquier tipo de ciencia.
### Energía
La energía puede definirse como la capacidad de suministrar calor o realizar un trabajo. Un tipo de trabajo ( es el proceso de hacer que la materia se mueva contra una fuerza opuesta. Por ejemplo, cuando inflamos un neumático de bicicleta realizamos un trabajo: movemos la materia (el aire de la bomba) contra la fuerza opuesta del aire que ya está en el neumático.
Al igual que la materia, la energía se presenta en diferentes tipos. Un esquema clasifica la energía en dos tipos: la energía potencial, que es la que tiene un objeto debido a su posición, composición o condición relativa, y la energía cinética, que es la que posee un objeto debido a su movimiento. El agua en la cima de una cascada o una presa tiene energía potencial debido a su posición; cuando fluye hacia abajo a través de los generadores, tiene energía cinética que puede ser utilizada para trabajar y producir electricidad en una planta hidroeléctrica (). Una batería tiene energía potencial porque las sustancias químicas que contiene pueden producir electricidad que puede realizar un trabajo.
La energía puede convertirse de una forma a otra, pero toda la energía presente, antes de que se produzca un cambio, siempre existe de alguna forma después de que se complete el cambio. Esta observación se expresa en la ley de conservación de la energía: durante un cambio físico o químico, la energía no puede crearse ni destruirse, aunque sí puede cambiar de forma. (Esta es también una versión de la primera ley de termodinámica, como aprenderá más adelante).
Cuando una sustancia se convierte en otra, siempre hay una conversión asociada de una forma de energía en otra. Por lo general, el calor se libera o se absorbe, pero a veces la conversión implica luz, energía eléctrica o alguna otra forma de energía. Por ejemplo, la energía química (un tipo de energía potencial) se almacena en las moléculas que componen la gasolina. Cuando la gasolina se quema en los cilindros del motor de un automóvil, los productos gaseosos de esta reacción química, que se expanden rápidamente, generan energía mecánica (un tipo de energía cinética) cuando mueven los pistones de los cilindros.
Según la ley de conservación de la materia (vista en un capítulo anterior), no hay un cambio detectable en la cantidad total de materia durante un cambio químico. Cuando se producen reacciones químicas, los cambios de energía son relativamente modestos y los cambios de masa son demasiado pequeños para medirlos, por lo que las leyes de conservación de la materia y la energía se mantienen. Sin embargo, en las reacciones nucleares, los cambios de energía son mucho mayores (en factores de un millón o más), los cambios de masa son medibles y las conversiones materia-energía son significativas. Esto se examinará con más detalle en un capítulo posterior sobre la química nuclear.
### Energía térmica, temperatura y calor
La energía térmica es la energía cinética asociada al movimiento aleatorio de los átomos y las moléculas. La temperatura es una medida cuantitativa de "calor" o "frío". Cuando los átomos y las moléculas de un objeto se mueven o vibran rápidamente, tienen una energía cinética (Kinetic Energy, KE) media más alta y decimos que el objeto está "caliente". Cuando los átomos y las moléculas se mueven lentamente, tienen una KE media más bajo y decimos que el objeto está "frío" (). Suponiendo que no se produzca ninguna reacción química o cambio de fase (como la fusión o la vaporización), el aumento de la cantidad de energía térmica en una muestra de materia hará que su temperatura aumente. Y, suponiendo que no se produzca ninguna reacción química o cambio de fase (como la condensación o la congelación), la disminución de la cantidad de energía térmica en una muestra de materia hará que su temperatura disminuya.
La mayoría de las sustancias se expanden al aumentar su temperatura y se contraen al disminuirla. Esta propiedad puede utilizarse para medir los cambios de temperatura, como se muestra en la . El funcionamiento de muchos termómetros depende de la expansión y contracción de las sustancias en respuesta a los cambios de temperatura.
El calor ( es la transferencia de energía térmica entre dos cuerpos a diferentes temperaturas. El flujo de calor (término redundante, pero de uso común) aumenta la energía térmica de un cuerpo y disminuye la del otro. Supongamos que tenemos inicialmente una sustancia de alta temperatura (y alta energía térmica) (H) y una sustancia de baja temperatura (y baja energía térmica) (L). Los átomos y moléculas de H tienen una KE media mayor que los de L. Si ponemos la sustancia H en contacto con la sustancia L, la energía térmica fluirá espontáneamente de la sustancia H a la sustancia L. La temperatura de la sustancia H disminuirá, al igual que la KE media de sus moléculas; la temperatura de la sustancia L aumentará, junto con la KE media de sus moléculas. El flujo de calor continuará hasta que las dos sustancias estén a la misma temperatura ().
La materia que sufre reacciones químicas y cambios físicos puede liberar o absorber calor. Un cambio que libera calor se llama proceso exotérmico. Por ejemplo, la reacción de combustión que se produce al utilizar un soplete oxiacetilénico es un proceso exotérmico; este proceso también libera energía en forma de luz, tal y como demuestra la llama del soplete (). Una reacción o cambio que absorbe calor es un proceso endotérmico. Una compresa fría utilizada para tratar las distensiones musculares es un ejemplo de proceso endotérmico. Cuando las sustancias de la compresa fría (agua y una sal como el nitrato de amonio) se juntan, el proceso resultante absorbe el calor, lo que provoca la sensación de frío.
Históricamente, la energía se medía en unidades de calorías (cal). Una caloría es la cantidad de energía necesaria para elevar un gramo de agua 1 grado C (1 kelvin). Sin embargo, esta cantidad depende de la presión atmosférica y de la temperatura inicial del agua. La facilidad para medir los cambios energéticos en calorías ha hecho que la caloría se siga utilizando con frecuencia. La Caloría (con C mayúscula), o caloría grande, utilizada habitualmente para cuantificar el contenido energético de los alimentos, es una kilocaloría. La unidad SI de calor, trabajo y energía es el julio. Un julio (J) se define como la cantidad de energía utilizada cuando una fuerza de 1 newton mueve un objeto 1 metro. Se llama así en honor al físico inglés James Prescott Joule. Un julio equivale a 1 kg m2/s2, que también se denomina 1 newton-metro. Un kilojulio (kJ) equivale a 1.000 julios. Para normalizar su definición, se ha establecido que 1 caloría equivale a 4,184 julios.
Ahora introducimos dos conceptos útiles para describir el flujo de calor y el cambio de temperatura. La capacidad calorífica ( de un cuerpo de materia es la cantidad de calor (q) que absorbe o libera cuando experimenta un cambio de temperatura (ΔT) de 1 grado Celsius (o, equivalentemente, 1 kelvin):
La capacidad calorífica viene determinada tanto por el tipo como por la cantidad de sustancia que absorbe o libera calor. Se trata, pues, de una propiedad extensiva: su valor es proporcional a la cantidad de la sustancia.
Por ejemplo, considere la capacidad calorífica de dos sartenes de hierro fundido. La capacidad calorífica de la sartén grande es cinco veces mayor que la de la sartén pequeña porque, aunque ambas están hechas del mismo material, la masa de la sartén grande es cinco veces mayor que la de la sartén pequeña. Más masa significa que hay más átomos en la sartén más grande, por lo que se necesita más energía para hacer que todos esos átomos vibren más rápido. La capacidad calorífica de la sartén pequeña de hierro fundido se observa que se necesita 18 150 J de energía para elevar la temperatura de la sartén en 50,0 °C:
La sartén más grande de hierro fundido, aunque está hecha de la misma sustancia, requiere 90 700 J de energía para elevar su temperatura en 50,0 °C. La sartén más grande tiene una capacidad térmica (proporcionalmente) mayor porque la mayor cantidad de material requiere una cantidad (proporcionalmente) mayor de energía para producir el mismo cambio de temperatura:
La capacidad calorífica específica ( de una sustancia, comúnmente llamada "calor específico", es la cantidad de calor necesaria para elevar la temperatura de 1 gramo de una sustancia en 1 grado Celsius (o 1 kelvin):
La capacidad calorífica específica depende únicamente del tipo de sustancia que absorbe o desprende calor. Es una propiedad intensiva: lo único que importa es el tipo, pero no la cantidad, de la sustancia. Por ejemplo, la sartén pequeña de hierro fundido tiene una masa de 808 g. Por lo tanto, el calor específico del hierro (el material utilizado para fabricar la sartén) es:
La sartén grande tiene una masa de 4040 g. Utilizando los datos de esta sartén, también podemos calcular el calor específico del hierro:
Aunque la sartén grande tiene más masa que la pequeña, como ambas están hechas del mismo material, ambas dan el mismo valor de calor específico (para el material de construcción, el hierro). Observe que el calor específico se mide en unidades de energía por temperatura y por masa y es una propiedad intensiva, ya que se deriva de un cociente de dos propiedades extensivas (calor y masa). La capacidad calorífica molar, también una propiedad intensiva, es la capacidad calorífica por mol de una determinada sustancia y tiene unidades de J/mol °C ().
El agua tiene un calor específico relativamente alto (unos 4,2 J/g °C para el líquido y 2,09 J/g °C para el sólido); la mayoría de los metales tienen calores específicos mucho más bajos (normalmente menos de 1 J/g °C). El calor específico de una sustancia varía un poco con la temperatura. Sin embargo, esta variación suele ser lo suficientemente pequeña como para que tratemos el calor específico como constante en el rango de temperaturas que se considerará en este capítulo. Los calores específicos de algunas sustancias comunes se enumeran en la .
Si conocemos la masa de una sustancia y su calor específico, podemos determinar la cantidad de calor, q, que entra o sale de la sustancia midiendo el cambio de temperatura antes y después de ganar o perder calor:
En esta ecuación, c es el calor específico de la sustancia, m es su masa y ΔT (que se lee "delta T") es el cambio de temperatura, Tfinal − Tinicial. Si una sustancia gana energía térmica, su temperatura aumenta, su temperatura final es mayor que su temperatura inicial, Tfinal − Tinicial tiene un valor positivo, y el valor de q es positivo. Si una sustancia pierde energía térmica, su temperatura disminuye, la temperatura final es menor que la inicial, Tfinal − Tinicial tiene un valor negativo, y el valor de q es negativo.
Tenga en cuenta que la relación entre el calor, el calor específico, la masa y el cambio de temperatura puede utilizarse para determinar cualquiera de estas cantidades (no solo el calor) si se conocen las otras tres o se pueden deducir.
### Conceptos clave y resumen
La energía es la capacidad de suministrar calor o realizar un trabajo (aplicar una fuerza para mover la materia). La energía cinética (Kinetic Energy, KE) es la energía del movimiento; la energía potencial es la energía debida a la posición relativa, la composición o el estado. Cuando la energía se convierte de una forma a otra, no se crea ni se destruye (ley de conservación de la energía o primera ley de termodinámica).
La energía térmica de la materia se debe a las energías cinéticas de los átomos o moléculas que la componen. La temperatura es una propiedad intensiva de la materia que refleja el calor o el frío y que aumenta a medida que aumenta la energía cinética media. El calor es la transferencia de energía térmica entre objetos a diferentes temperaturas. Los procesos químicos y físicos pueden absorber calor (endotérmico) o liberarlo (exotérmico). La unidad SI de energía, calor y trabajo es el julio (J).
El calor específico y la capacidad calorífica son medidas de la energía necesaria para cambiar la temperatura de una sustancia u objeto. La cantidad de calor absorbida o liberada por una sustancia depende directamente del tipo de sustancia, de su masa y del cambio de temperatura que experimenta.
### Ecuaciones clave
### Ejercicios de química del final del capítulo
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# Termoquímica
## Calorimetría
Una de las técnicas que podemos utilizar para medir la cantidad de calor que interviene en un proceso químico o físico se conoce como calorimetría. La calorimetría se utiliza para medir las cantidades de calor transferidas hacia o desde una sustancia. Para ello, se intercambia el calor con un objeto calibrado (calorímetro). El cambio de temperatura medido por el calorímetro se utiliza para obtener la cantidad de calor transferida por el proceso estudiado. La medición de la transferencia de calor utilizando este enfoque requiere la definición de un sistema (la sustancia o sustancias que sufren el cambio físico o químico) y su entorno (todas las demás materias, incluidos los componentes del aparato de medición, que sirven para proporcionar calor al sistema o absorberlo).
Un calorímetro es un dispositivo que se utiliza para medir la cantidad de calor que interviene en un proceso químico o físico. Por ejemplo, cuando se produce una reacción exotérmica en una solución en un calorímetro, el calor producido por la reacción es absorbido por la solución, lo que aumenta su temperatura. Cuando se produce una reacción endotérmica, el calor necesario se absorbe de la energía térmica de la solución, lo que disminuye su temperatura (). El cambio de temperatura, junto con el calor específico y la masa de la solución, puede utilizarse entonces para calcular la cantidad de calor implicada en ambos casos.
Las mediciones de calorimetría son importantes para comprender las transferencias de calor en las reacciones en las que intervienen desde proteínas microscópicas hasta máquinas masivas. Durante su estancia en la Oficina Nacional de Estándares, la química investigadora Reatha Clark King realizó experimentos calorimétricos para conocer los calores precisos de varios compuestos del flúor. Su trabajo fue importante para la NASA en su búsqueda de mejores combustibles para cohetes.
Los científicos utilizan calorímetros bien aislados que prácticamente impiden la transferencia de calor entre el calorímetro y su entorno, lo que limita de hecho el "entorno" a los componentes que no forman parte del sistema con el calorímetro (y el propio calorímetro). Esto permite determinar con precisión el calor implicado en los procesos químicos, el contenido energético de los alimentos, etc. Los estudiantes de química general suelen utilizar calorímetros sencillos construidos con vasos de poliestireno (). Estos calorímetros de "taza de café", fáciles de usar, permiten un mayor intercambio de calor con el entorno exterior y, por tanto, producen valores energéticos menos precisos.
También existen calorímetros de solución comerciales. Los calorímetros relativamente baratos suelen consistir en dos vasos de paredes finas que se anidan de forma que se minimiza el contacto térmico durante su uso, junto con una tapa aislada, un agitador de mano y un termómetro sencillo. Los calorímetros más caros utilizados para la industria y la investigación suelen tener un recipiente de reacción bien aislado y completamente cerrado, un mecanismo de agitación motorizado y un sensor de temperatura más preciso ().
Antes de hablar de la calorimetría de las reacciones químicas, consideremos un ejemplo más sencillo que ilustra la idea central de la calorimetría. Supongamos que tenemos inicialmente una sustancia de alta temperatura, como un trozo de metal caliente (M), y una sustancia de baja temperatura, como el agua fría (W). Si colocamos el metal en el agua, el calor fluirá de M a W. La temperatura de M disminuirá y la de W aumentará hasta que las dos sustancias tengan la misma temperatura, es decir, cuando alcancen el equilibrio térmico (). Si esto ocurre en un calorímetro, lo ideal es que toda esta transferencia de calor se produzca entre las dos sustancias sin que se gane o se pierda calor por su entorno externo. En estas circunstancias ideales, el cambio de calor neto es cero:
Esta relación puede reordenarse para mostrar que el calor ganado por la sustancia M es igual al calor perdido por la sustancia W:
La magnitud del calor (cambio) es, por tanto, la misma para ambas sustancias y el signo negativo se limita a mostrar que qsustancia M y qsustancia W son opuestas en cuanto a la dirección del flujo de calor (ganancia o pérdida), pero no indica el signo aritmético de ninguno de los dos valores de q (que viene determinado por si la materia en cuestión gana o pierde calor, por definición). En la situación concreta descrita, qsustancia M es un valor negativo y qsustancia W es positivo, ya que el calor se transfiere de M a W.
Este método también puede utilizarse para determinar otras cantidades, como el calor específico de un metal desconocido.
Cuando utilizamos la calorimetría para determinar el calor involucrado en una reacción química, se aplican los mismos principios que hemos estado discutiendo. La cantidad de calor absorbida por el calorímetro suele ser lo suficientemente pequeña como para poder despreciarla (aunque no para realizar mediciones muy precisas, como se verá más adelante), y el calorímetro minimiza el intercambio de energía con el entorno exterior. Como la energía no se crea ni se destruye durante una reacción química, el calor producido o consumido en la reacción (el "sistema"), qreacción, más el calor absorbido o perdido por la solución (el "entorno"), qsolución, deben sumar cero:
Esto significa que la cantidad de calor producida o consumida en la reacción es igual a la cantidad de calor absorbida o perdida por la solución:
Este concepto se encuentra en el corazón de todos los problemas y cálculos de calorimetría.
Si la cantidad de calor absorbida por un calorímetro es demasiado grande para despreciarla o si necesitamos resultados más precisos, debemos tener en cuenta el calor absorbido tanto por la solución como por el calorímetro.
Los calorímetros descritos están diseñados para funcionar a presión constante (atmosférica) y son convenientes para medir el flujo de calor que acompaña a los procesos que ocurren en la solución. Otro tipo de calorímetro que funciona a volumen constante, conocido coloquialmente como calorímetro de bomba, se utiliza para medir la energía producida por reacciones que generan grandes cantidades de calor y productos gaseosos, como las reacciones de combustión. (El término "bomba" proviene de la observación de que estas reacciones pueden ser lo suficientemente vigorosas como para parecerse a explosiones que dañarían otros calorímetros.) Este tipo de calorímetro consiste en un robusto recipiente de acero (la "bomba") que contiene los reactivos y está a su vez sumergido en agua (). La muestra se coloca en la bomba, que se llena de oxígeno a alta presión. Se utiliza una pequeña chispa eléctrica para encender la muestra. La energía producida por la reacción es absorbida por la bomba de acero y el agua circundante. Se mide el aumento de temperatura y, junto con la capacidad calorífica conocida del calorímetro, se utiliza para calcular la energía producida por la reacción. Los calorímetros de bomba requieren una calibración para determinar la capacidad calorífica del calorímetro y garantizar la exactitud de los resultados. La calibración se realiza utilizando una reacción con un q conocido, como una cantidad medida de ácido benzoico encendida por una chispa de un hilo fusible de níquel que se pesa antes y después de la reacción. El cambio de temperatura producido por la reacción conocida se utiliza para determinar la capacidad calorífica del calorímetro. Por lo general, la calibración se realiza siempre antes de que el calorímetro se utilice para recopilar datos de investigación.
Desde que se construyó el primero en 1899, se han construido 35 calorímetros para medir el calor producido por una persona viva.Francis D. Reardon et al. "El calorímetro humano Snellen revisado, rediseñado y mejorado: Características de diseño y rendimiento". Estos calorímetros de cuerpo entero de diversos diseños son lo suficientemente grandes como para albergar a un ser humano. Más recientemente, los calorímetros de habitación completa permiten realizar actividades relativamente normales, y estos calorímetros generan datos que reflejan más fielmente el mundo real. Estos calorímetros se utilizan para medir el metabolismo de los individuos en diferentes condiciones ambientales, diferentes regímenes dietéticos y con diferentes condiciones de salud, como la diabetes.
Por ejemplo, el equipo de Carla Prado, de la Universidad de Alberta, realizó una calorimetría de cuerpo entero para conocer el gasto energético de las mujeres que habían dado a luz recientemente. Estudios como este permiten elaborar mejores recomendaciones y regímenes de nutrición, ejercicio y bienestar general durante este periodo de importantes cambios fisiológicos. En los seres humanos, el metabolismo se mide normalmente en calorías por día. Una caloría nutricional (Caloría) es la unidad de energía utilizada para cuantificar la cantidad de energía derivada del metabolismo de los alimentos; una Caloría es igual a 1.000 calorías (1 kcal), la cantidad de energía necesaria para calentar 1 kg de agua en 1 °C.
### Conceptos clave y resumen
La calorimetría se utiliza para medir la cantidad de energía térmica transferida en un proceso químico o físico. Para ello es necesario medir cuidadosamente el cambio de temperatura que se produce durante el proceso y las masas del sistema y del entorno. Estas cantidades medidas se utilizan para calcular la cantidad de calor producida o consumida en el proceso mediante relaciones matemáticas conocidas.
Los calorímetros están diseñados para minimizar el intercambio de energía entre su contenido y el ambiente externo. Van desde simples calorímetros de taza de café utilizados por los estudiantes de química principiantes hasta sofisticados calorímetros de bomba utilizados para determinar el contenido energético de los alimentos.
### Ejercicios de química del final del capítulo
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# Termoquímica
## Entalpía
La termoquímica es una rama de la termodinámica química, la ciencia que se ocupa de las relaciones entre el calor, el trabajo y otras formas de energía en el contexto de los procesos químicos y físicos. Como en este capítulo nos centramos en la termoquímica, debemos tener en cuenta algunos conceptos de la termodinámica muy utilizados.
Las sustancias actúan como depósitos de energía, lo que significa que se les puede añadir o quitar energía. La energía se almacena en una sustancia cuando se eleva la energía cinética de sus átomos o moléculas. La mayor energía cinética puede darse en forma de mayores traslaciones (desplazamientos o movimientos en línea recta), vibraciones o rotaciones de los átomos o moléculas. Cuando se pierde energía térmica, las intensidades de estos movimientos disminuyen y la energía cinética cae. El total de todos los tipos posibles de energía presentes en una sustancia se llama energía interna (, a veces simbolizada como E.
Cuando un sistema sufre un cambio, su energía interna puede cambiar y la energía puede transferirse del sistema al entorno, o del entorno al sistema. La energía se transfiere a un sistema cuando este absorbe calor (q) del entorno o cuando el entorno realiza un trabajo (w) sobre el sistema. Por ejemplo, la energía se transfiere a un alambre metálico a temperatura ambiente si se sumerge en agua caliente (el alambre absorbe el calor del agua), o si se dobla rápidamente el alambre hacia adelante y hacia atrás (el alambre se calienta debido al trabajo realizado sobre él). Ambos procesos aumentan la energía interna del alambre, lo que se refleja en un aumento de su temperatura. A la inversa, la energía se transfiere fuera de un sistema cuando se pierde calor de este, o cuando el sistema realiza un trabajo en el entorno.
La relación entre la energía interna, el calor y el trabajo puede representarse mediante la ecuación:
como se muestra en la . Esta es una versión de la primera ley de termodinámica, y muestra que la energía interna de un sistema cambia a través del flujo de calor que entra o sale del sistema (q positivo es el flujo de calor que entra; q negativo es el flujo de calor que sale) o el trabajo realizado en o por el sistema. El trabajo, w, es positivo si se realiza sobre el sistema y negativo si lo realiza el sistema.
Un tipo de trabajo llamado trabajo de expansión (o trabajo de presión-volumen) se produce cuando un sistema empuja hacia atrás el entorno contra una presión de contención, o cuando el entorno comprime el sistema. Un ejemplo de esto ocurre durante el funcionamiento de un motor de combustión interna. La reacción de la gasolina y el oxígeno es exotérmica. Una parte de esta energía se desprende en forma de calor, y otra trabaja empujando el pistón en el cilindro. Las sustancias que intervienen en la reacción son el sistema, y el motor y el resto del universo son el entorno. El sistema pierde energía tanto por el calentamiento como por el trabajo que realiza en el entorno y su energía interna disminuye. (El motor es capaz de mantener el automóvil en movimiento porque este proceso se repite muchas veces por segundo mientras el motor está en marcha.) En el capítulo dedicado a la termodinámica veremos cómo determinar la cantidad de trabajo que supone un cambio físico o químico.
Como se ha comentado, la relación entre energía interna, calor y trabajo puede representarse como ΔU = q + w. La energía interna es un ejemplo de función de estado (o variable de estado), mientras que el calor y el trabajo no son funciones de estado. El valor de una función de estado depende solo del estado en el que se encuentra un sistema y no de cómo se llega a ese estado. Si una cantidad no es una función de estado, su valor sí depende de cómo se alcanza el estado. Un ejemplo de función de estado es la altitud o la elevación. Si está en la cima del monte Kilimanjaro, se encuentra a una altitud de 5895 m y no importa si llegó a pie o en paracaídas. Sin embargo, la distancia recorrida hasta la cima del Kilimanjaro no es una función de estado. Se puede subir a la cima por una ruta directa o por un camino más indirecto y tortuoso (). Las distancias recorridas serían diferentes (la distancia no es una función de estado), pero la altitud alcanzada sería la misma (la altitud es una función de estado).
Los químicos suelen utilizar una propiedad conocida como entalpía ( para describir la termodinámica de los procesos químicos y físicos. La entalpía se define como la suma de la energía interna de un sistema (U) y el producto matemático de su presión (P) y su volumen (V):
La entalpía también es una función de estado. Los valores de entalpía de las sustancias específicas no pueden medirse directamente; solo pueden determinarse los cambios de entalpía de los procesos químicos o físicos. Para los procesos que tienen lugar a presión constante (una condición común para muchos cambios químicos y físicos), el cambio de entalpía (Δ es:
El producto matemático PΔV representa el trabajo (w), es decir, la expansión o el trabajo presión-volumen como se ha señalado. Por sus definiciones, los signos aritméticos de ΔV y w serán siempre opuestos:
Sustituyendo esta ecuación y la definición de energía interna en la ecuación de cambio de entalpía se obtiene:
donde q es el calor de reacción en condiciones de presión constante.
Y así, si un proceso químico o físico se lleva a cabo a presión constante con el único trabajo realizado causado por la expansión o la contracción, entonces el flujo de calor(q) y el cambio de entalpía (ΔH) para el proceso son iguales.
El calor que se desprende al hacer funcionar un mechero Bunsen es igual al cambio de entalpía de la reacción de combustión del metano que tiene lugar, ya que se produce a la presión esencialmente constante de la atmósfera. Por otro lado, el calor producido por una reacción medida en un calorímetro de bomba () no es igual a ΔH porque el recipiente metálico cerrado y de volumen constante impide que la presión permanezca constante (puede aumentar o disminuir si la reacción produce cantidades mayores o menores de especies gaseosas). Los químicos suelen realizar experimentos en condiciones atmosféricas normales, a presión externa constante con q = ΔH, lo que hace que la entalpía sea la opción más conveniente para determinar los cambios de calor de las reacciones químicas.
Las siguientes convenciones se aplican cuando se utiliza ΔH:
1. Un valor negativo de un cambio de entalpía, Δ
2. Los químicos utilizan una ecuación termoquímica para representar los cambios de materia y energía. En una ecuación termoquímica, el cambio de entalpía de una reacción se muestra como un valor de Δ
Esta ecuación indica que cuando 1 mol de gas hidrógeno y
3. El cambio de entalpía de una reacción depende de los estados físicos de los reactivos y los productos, por lo que estos deben mostrarse. Por ejemplo, cuando 1 mol de gas hidrógeno y
Asegúrese de tener en cuenta tanto la estequiometría como los reactivos limitantes cuando determine el ΔH de una reacción química.
Los cambios de entalpía se suelen tabular para las reacciones en las que tanto los reactivos como los productos se encuentran en las mismas condiciones. Un estado estándar es un conjunto de condiciones comúnmente aceptado que se utiliza como punto de referencia para la determinación de las propiedades en otras condiciones diferentes. Para los químicos, el estado estándar de la IUPAC se refiere a materiales bajo una presión de 1 bar y a soluciones a 1 M, y no especifica una temperatura. Muchas tablas termoquímicas enumeran valores con un estado estándar de 1 atmósfera (atm). Dado que el ΔH de una reacción cambia muy poco con cambios tan pequeños en la presión (1 bar = 0,987 atm), los valores de ΔH (excepto los valores medidos con mayor precisión) son esencialmente los mismos en ambos conjuntos de condiciones estándar. Incluiremos un "°" en superíndice en el símbolo de cambio de entalpía para designar el estado estándar. Dado que la temperatura habitual (pero no técnicamente estándar) es 298,15 K, se asumirá esta temperatura a menos que se especifique otra. Así, el símbolo se utiliza para indicar un cambio de entalpía para un proceso que ocurre en estas condiciones. (El símbolo ΔH se utiliza para indicar un cambio de entalpía para una reacción que ocurre en condiciones no estándar.)
Los cambios de entalpía para muchos tipos de procesos químicos y físicos están disponibles en la literatura de referencia, incluyendo los de las reacciones de combustión, transiciones de fase y reacciones de formación. Al discutir estas cantidades, es importante prestar atención a la naturaleza extensiva de la entalpía y los cambios de entalpía. Dado que el cambio de entalpía para una reacción dada es proporcional a las cantidades de sustancias involucradas, puede informarse sobre esa base (es decir, como el ΔH para cantidades específicas de reactivos). Sin embargo, a menudo nos resulta más útil dividir una propiedad extensiva (ΔH) por otra (cantidad de sustancia), e informar de un valor intensivo por cantidad de ΔH, a menudo "normalizado" a una base por mol. (Note que esto es similar a la determinación del calor específico de la propiedad intensiva a partir de la capacidad calorífica de la propiedad extensiva, como se vio anteriormente.)
### Entalpía estándar de combustión
Entalpía estándar de combustión es el cambio de entalpía cuando 1 mol de una sustancia arde (se combina vigorosamente con el oxígeno) en condiciones de estado estándar; a veces se denomina "calor de combustión". Por ejemplo, la entalpía de combustión del etanol, −1366,8 kJ/mol, es la cantidad de calor que se produce cuando un mol de etanol se somete a una combustión completa a 25 °C y una presión de 1 atmósfera, dando lugar a productos también a 25 °C y 1 atm.
Se han medido las entalpías de combustión de muchas sustancias; algunas de ellas se enumeran en la . Se utilizan como combustibles muchas sustancias fácilmente disponibles con grandes entalpías de combustión, como el hidrógeno, el carbono (como el carbón o el carbón vegetal) y los hidrocarburos (compuestos que solo contienen hidrógeno y carbono), como el metano, el propano y los principales componentes de la gasolina.
### Entalpía estándar de formación
Una entalpía estándar de formación es un cambio de entalpía para una reacción en la que se forma exactamente 1 mol de una sustancia pura a partir de elementos libres en sus estados más estables en condiciones de estado estándar. Estos valores son especialmente útiles para calcular o predecir los cambios de entalpía de las reacciones químicas que son poco prácticas o peligrosas de llevar a cabo, o para los procesos para los que es difícil hacer mediciones. Si tenemos los valores de las entalpías de formación estándar adecuadas, podemos determinar el cambio de entalpía para cualquier reacción, lo que practicaremos en la siguiente sección sobre la ley de Hess.
La entalpía estándar de formación del CO2(g) es de -393,5 kJ/mol. Este es el cambio de entalpía para la reacción exotérmica:
comenzando con los reactivos a una presión de 1 atm y 25 °C (con el carbono presente como grafito, la forma más estable del carbono en estas condiciones) y terminando con un mol de CO2, también a 1 atm y 25 °C. Para el dióxido de nitrógeno, NO2(g), es de 33,2 kJ/mol. Este es el cambio de entalpía para la reacción:
Una ecuación de reacción con mol de N2 y 1 mol de O2 es correcto en este caso porque la entalpía estándar de formación siempre se refiere a 1 mol de producto, NO2(g).
En el Apéndice G encontrará una tabla de entalpías de formación estándar de muchas sustancias comunes. Estos valores indican que las reacciones de formación van desde altamente exotérmicas (como −2984 kJ/mol para la formación de P4O10) hasta fuertemente endotérmicas (como +226,7 kJ/mol para la formación de acetileno, C2H2). Por definición, la entalpía estándar de formación de un elemento en su forma más estable es igual a cero en condiciones estándar, que es 1 atm para los gases y 1 M para las soluciones.
### Ley de Hess
Hay dos maneras de determinar la cantidad de calor implicada en un cambio químico: medirla experimentalmente o calcularla a partir de otros cambios de entalpía determinados experimentalmente. Algunas reacciones son difíciles, si no imposibles, de investigar y realizar mediciones precisas de forma experimental. E incluso cuando una reacción no es difícil de realizar o medir, es conveniente poder determinar el calor implicado en una reacción sin tener que realizar un experimento.
Este tipo de cálculo suele implicar el uso de la ley de Hess, que establece: Si un proceso puede escribirse como la suma de varios procesos escalonados, el cambio de entalpía del proceso total es igual a la suma de los cambios de entalpía de los distintos pasos. La ley de Hess es válida porque la entalpía es una función de estado: Los cambios de entalpía solo dependen de dónde empieza y termina un proceso químico, pero no del camino que sigue desde el principio hasta el final. Por ejemplo, podemos pensar que la reacción del carbono con el oxígeno para formar dióxido de carbono se produce directamente o mediante un proceso de dos pasos. El proceso directo está escrito:
En el proceso de dos pasos, primero se forma monóxido de carbono:
A continuación, el monóxido de carbono reacciona para formar dióxido de carbono:
La ecuación que describe la reacción global es la suma de estos dos cambios químicos:
Como el CO producido en el paso 1 se consume en el paso 2, el cambio neto es:
Según la ley de Hess, el cambio de entalpía de la reacción será igual a la suma de los cambios de entalpía de los pasos.
El resultado se muestra en la . Vemos que el ΔH de la reacción global es el mismo tanto si se produce en un paso como en dos. Esta conclusión (ΔH global de la reacción = suma de los valores de ΔH de los "pasos" de la reacción global) es cierta en general para los procesos químicos y físicos.
Antes de seguir practicando el uso de la ley de Hess, recordemos dos características importantes del ΔH.
1. Δ
Cuando se forman 2 moles de NO
En general, si multiplicamos o dividimos una ecuación por un número, el cambio de entalpía también debe multiplicarse o dividirse por el mismo número.
2. El Δ
Entonces, para la reacción "inversa", el cambio de entalpía también se "invierte":
Se presenta un ejemplo un poco menos sencillo que ilustra el proceso de reflexión que implica la resolución de muchos problemas de la ley de Hess. Muestra cómo podemos encontrar muchas entalpías de formación estándar (y otros valores de ΔH) si son difíciles de determinar experimentalmente.
También podemos utilizar la ley de Hess para determinar el cambio de entalpía de cualquier reacción si se dispone de las correspondientes entalpías de formación de los reactivos y productos. Las reacciones escalonadas que consideramos son: (i) descomposiciones de los reactivos en los elementos que los componen (para las que los cambios de entalpía son proporcionales al negativo de las entalpías de formación de los reactivos), seguidas de (ii) recombinaciones de los elementos para dar los productos (con los cambios de entalpía proporcionales a las entalpías de formación de los productos). El cambio de entalpía estándar de la reacción global es, por tanto, igual a: (ii) la suma de las entalpías estándar de formación de todos los productos más (i) la suma de los negativos de las entalpías estándar de formación de los reactivos. Esto se suele reordenar ligeramente para escribirlo como sigue, con ∑ representando "la suma de" y n representando los coeficientes estequiométricos:
El siguiente ejemplo muestra en detalle por qué esta ecuación es válida y cómo utilizarla para calcular el cambio de entalpía para una reacción de interés.
### Conceptos clave y resumen
Si un cambio químico se lleva a cabo a presión constante y el único trabajo realizado es el causado por la expansión o la contracción, q para el cambio se llama cambio de entalpía con el símbolo ΔH, o para reacciones que ocurren en condiciones de estado estándar a 298 K. El valor de ΔH para una reacción en una dirección es igual en magnitud, pero de signo contrario, a ΔH para la reacción en la dirección opuesta, y ΔH es directamente proporcional a la cantidad de reactivos y productos. La entalpía estándar de formación, es el cambio de entalpía que acompaña a la formación de 1 mol de una sustancia a partir de los elementos en sus estados más estables a 1 bar y 298,15 K. Si se dispone de las entalpías de formación de los reactivos y los productos de una reacción, el cambio de entalpía puede calcularse mediante la ley de Hess: Si un proceso puede escribirse como la suma de varios procesos escalonados, el cambio de entalpía del proceso total es igual a la suma de los cambios de entalpía de los distintos pasos.
### Ecuaciones clave
### Ejercicios de química del final del capítulo
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# Estructura electrónica y propiedades periódicas de los elementos
## Introducción
En 1054, los astrónomos chinos registraron la aparición de una "estrella invitada" en el cielo, visible incluso durante el día, que luego desapareció lentamente durante los dos años siguientes. La repentina aparición se debió a la explosión de una supernova, mucho más brillante que la estrella original. Aunque esta supernova se observó hace casi un milenio, la Nebulosa del Cangrejo restante () sigue liberando energía en la actualidad. No solo emite luz visible, sino también luz infrarroja, rayos X y otras formas de radiación electromagnética. La nebulosa emite tanto espectros continuos (el resplandor blanco-azulado) como espectros de emisión atómica (los filamentos de color). En este capítulo hablaremos de la luz y otras formas de radiación electromagnética y de cómo se relacionan con la estructura electrónica de los átomos. También veremos cómo esta radiación puede utilizarse para identificar elementos, incluso a miles de años luz de distancia. |
# Estructura electrónica y propiedades periódicas de los elementos
## Energía electromagnética
La naturaleza de la luz ha sido objeto de investigación desde la antigüedad. En el siglo XVII, Isaac Newton realizó experimentos con lentes y prismas y pudo demostrar que la luz blanca está formada por los colores individuales del arco iris combinados. Newton explicó sus descubrimientos sobre la óptica en términos de una visión "corpuscular" de la luz, en la que esta se componía de corrientes de partículas extremadamente diminutas que viajaban a gran velocidad según las leyes del movimiento de Newton. En ese mismo siglo, otros, como Christiaan Huygens, habían demostrado que fenómenos ópticos como la reflexión y la refracción podían explicarse igualmente en términos de luz como ondas que viajan a gran velocidad a través de un medio llamado "éter luminífero" que se pensaba impregnaba todo el espacio. A principios del siglo XIX, Thomas Young demostró que la luz que pasaba por rendijas estrechas y poco espaciadas producía patrones de interferencia que no podían explicarse en términos de partículas newtonianas, pero sí en términos de ondas. Más adelante, en el siglo XIX, después de que James Clerk Maxwell desarrollara su teoría de la radiación electromagnética y demostrara que la luz era la parte visible de un amplio espectro de ondas electromagnéticas, la visión de la luz con base en las partículas quedó totalmente desacreditada. A finales del siglo XIX, los científicos consideraban que el universo físico comprendía, a grandes rasgos, dos ámbitos distintos: la materia, compuesta por partículas que se mueven según las leyes del movimiento de Newton, y la radiación electromagnética, formada por ondas que se rigen por las ecuaciones de Maxwell. En la actualidad, estos ámbitos se denominan mecánica clásica y electrodinámica clásica (o electromagnetismo clásico). Aunque había algunos fenómenos físicos que no podían explicarse dentro de este marco, los científicos de la época estaban tan seguros de la solidez general de este marco que consideraban estas aberraciones como paradojas desconcertantes que finalmente se resolverían de alguna manera dentro de este marco. Como veremos, estas paradojas condujeron a un marco contemporáneo que conecta íntimamente las partículas y las ondas a un nivel fundamental llamado dualidad onda-partícula, que ha superado la visión clásica.
La luz visible y otras formas de radiación electromagnética desempeñan un papel importante en la química, ya que pueden utilizarse para inferir las energías de los electrones dentro de los átomos y las moléculas. Gran parte de la tecnología moderna se basa en la radiación electromagnética. Por ejemplo, las ondas de radio de un teléfono móvil, los rayos X utilizados por los dentistas, la energía utilizada para cocinar los alimentos en el microondas, el calor radiante de los objetos al rojo vivo y la luz de la pantalla del televisor son formas de radiación electromagnética que presentan un comportamiento ondulatorio.
### Ondas
Una onda es una oscilación o movimiento periódico que puede transportar energía de un punto a otro del espacio. Hay ejemplos comunes de ondas a nuestro alrededor. Agitar el extremo de una cuerda transfiere energía de la mano al otro extremo de la cuerda, dejar caer un guijarro en un estanque hace que las olas ondulen hacia afuera a lo largo de la superficie del agua, y la expansión del aire que acompaña a un rayo genera ondas sonoras (truenos) que pueden viajar hacia afuera durante varias millas. En cada uno de estos casos, la energía cinética se transfiere a través de la materia (la cuerda, el agua o el aire) mientras la materia permanece esencialmente en su lugar. Un ejemplo claro de onda se produce en los estadios deportivos cuando los aficionados de una zona estrecha de asientos se levantan simultáneamente y permanecen con los brazos en alto durante unos segundos antes de volver a sentarse, mientras que los aficionados de las secciones vecinas se levantan y se sientan igualmente en secuencia. Aunque esta ola puede rodear rápidamente un gran estadio en pocos segundos, ninguno de los aficionados se desplaza realmente con la ola: todos permanecen en sus asientos o por encima de ellos.
Las ondas no tienen por qué limitarse a viajar a través de la materia. Como demostró Maxwell, las ondas electromagnéticas están formadas por un campo eléctrico que oscila al compás de un campo magnético perpendicular, ambos perpendiculares a la dirección de desplazamiento. Estas ondas pueden viajar a través del vacío a una velocidad constante de 2998 108 m/s, la velocidad de la luz (denominada c).
Todas las ondas, incluidas las formas de radiación electromagnética, se caracterizan por una longitud de onda (denotada por λ, la letra griega minúscula lambda), una frecuencia (denotada por ν, la letra griega minúscula nu) y una amplitud. Como puede verse en la , la longitud de onda es la distancia entre dos picos o valles consecutivos de una onda (medida en metros en el sistema SI). Las ondas electromagnéticas tienen longitudes de onda que se sitúan en un rango enorme: se han observado longitudes de onda de kilómetros (103 m) a picómetros (10−12 m). La frecuencia es el número de ciclos de onda que pasan por un punto concreto del espacio en un tiempo determinado (en el Sistema Internacional [SI] de Unidades se mide en segundos). Un ciclo corresponde a una longitud de onda completa. La unidad de la frecuencia, expresada en ciclos por segundo [s−1], es el hercio (Hz). Los múltiplos comunes de esta unidad son los megahercios, (1 MHz = 1 106 Hz) y gigahercios (1 GHz = 1 109 Hz). La amplitud corresponde a la magnitud del desplazamiento de la onda y, por tanto, en la , corresponde a la mitad de la altura entre los picos y los valles. La amplitud está relacionada con la intensidad de la onda, que en el caso de la luz es el brillo, y en el del sonido es el volumen.
El producto de la longitud de onda (λ) de una onda y su frecuencia (ν), λν, es la velocidad de la onda. Así, en la radiación electromagnética en el vacío, la velocidad es igual a la constante fundamental, c:
La longitud de onda y la frecuencia son inversamente proporcionales: a medida que la longitud de onda aumenta, la frecuencia disminuye. La proporcionalidad inversa se ilustra en la . Esta figura también muestra el espectro electromagnético, el rango de todos los tipos de radiación electromagnética. Cada uno de los distintos colores de la luz visible tiene frecuencias y longitudes de onda específicas asociadas, y se puede ver que la luz visible constituye solo una pequeña parte del espectro electromagnético. Dado que las tecnologías desarrolladas para trabajar en distintas partes del espectro electromagnético son diferentes, por razones de conveniencia y legados históricos, se suelen utilizar distintas unidades para las diferentes partes del espectro. Por ejemplo, las ondas de radio suelen especificarse como frecuencias (normalmente en unidades de MHz), mientras que la región visible suele especificarse en longitudes de onda (normalmente en unidades de nm o angstroms).
Un fenómeno especialmente característico de las ondas se produce cuando dos o más ondas entran en contacto: Interfieren entre sí. La muestra los patrones de interferencia que surgen cuando la luz pasa a través de rendijas estrechas separadas por una longitud de onda. Los patrones de franjas que se producen dependen de la longitud de onda, estando las franjas más espaciadas para la luz de menor longitud de onda que pasa a través de un determinado conjunto de rendijas. Cuando la luz pasa a través de las dos rendijas, cada una de ellas actúa como una nueva fuente, lo que da lugar a dos ondas estrechamente espaciadas que entran en contacto en el detector (la cámara en este caso). Las regiones oscuras en la corresponden a las regiones donde los picos de la onda de una rendija coinciden con los valles de la onda de la otra rendija (interferencia destructiva), mientras que las regiones más brillantes corresponden a las regiones donde los picos de las dos ondas (o sus dos valles) coinciden (interferencia constructiva). Del mismo modo, cuando se lanzan dos piedras juntas en un estanque, se aprecian patrones de interferencia en las interacciones entre las ondas producidas por las piedras. Estos patrones de interferencia no pueden ser explicados por partículas que se mueven según las leyes de la mecánica clásica.
No todas las ondas son ondas viajeras. Las ondas (conocidas como ondas estacionarias) permanecen limitadas a una región del espacio. Como veremos, las ondas estacionarias desempeñan un papel importante en nuestra comprensión de la estructura electrónica de átomos y moléculas. El ejemplo más sencillo de una onda estacionaria es una onda unidimensional asociada a una cuerda que vibra y que se mantiene fija en sus dos extremos. La muestra las cuatro ondas estacionarias de menor energía (la onda fundamental y los tres armónicos más bajos) para una cuerda que vibra con una amplitud determinada. Aunque el movimiento de la cuerda se encuentra en su mayor parte dentro de un plano, la propia onda se considera unidimensional, ya que se encuentra a lo largo de la longitud de la cuerda. El movimiento de los segmentos de cuerda en una dirección perpendicular a la longitud de ella genera ondas y así la amplitud de estas es visible como el desplazamiento máximo de las curvas que se ven en la . La observación clave de la figura es que solo pueden formarse aquellas ondas que tengan un número entero, n, de semilongitudes de onda entre los puntos extremos. Un sistema con puntos finales fijos como este restringe el número y el tipo de las posibles formas de onda. Este es un ejemplo de cuantización en el que solo se observan valores discretos de un conjunto más general de valores continuos de alguna propiedad. Otra observación importante es que las ondas armónicas (aquellas ondas que muestran más de media longitud de onda) tienen todas uno o más puntos entre los dos puntos extremos que no están en movimiento. Estos puntos especiales son los nodos. Las energías de las ondas estacionarias con una amplitud dada en una cuerda vibrante aumentan con el número de semilongitudes n de onda. Dado que el número de nodos es n - 1, también se puede decir que la energía depende del número de nodos, aumentando generalmente a medida que el número de estos aumenta.
Se muestra un ejemplo de ondas estacionarias bidimensionales en la donde se ven los patrones de vibración en una superficie plana. Aunque las amplitudes vibratorias no pueden verse como en la cuerda vibrante, los nodos se hicieron visibles espolvoreando la superficie del tambor con un polvo que se acumula en las zonas de la superficie que tienen un desplazamiento mínimo. En las ondas estacionarias unidimensionales, los nodos eran puntos en la línea, pero en las ondas estacionarias bidimensionales, los nodos son líneas en la superficie (para las ondas estacionarias tridimensionales, los nodos son superficies bidimensionales dentro del volumen tridimensional).
### La radiación de cuerpo negro y la catástrofe ultravioleta
Las últimas décadas del siglo XIX fueron testigo de una intensa actividad de investigación para comercializar la recién descubierta iluminación eléctrica. Para ello era necesario conocer mejor las distribuciones de la luz emitida por las distintas fuentes consideradas. La iluminación artificial suele estar diseñada para imitar la luz solar natural dentro de las limitaciones de la tecnología existente. Esta iluminación consiste en un rango de frecuencias ampliamente distribuidas que forman un espectro continuo. La muestra la distribución de la longitud de onda para la luz solar. La radiación más intensa se encuentra en la región visible, mientras que la intensidad disminuye rápidamente en el caso de la luz ultravioleta (UV) de menor longitud de onda, y más lentamente en el caso de la luz infrarroja (IR) de mayor longitud de onda.
En la , la distribución solar se compara con una distribución representativa, denominada espectro del cuerpo negro, que corresponde a una temperatura de 5250 °C. El espectro del cuerpo negro se ajusta bastante bien al espectro solar. Un cuerpo negro es un emisor ideal que se aproxima al comportamiento de muchos materiales cuando se calientan. Es "ideal" en el mismo sentido que un gas ideal es una representación conveniente y sencilla de los gases reales que funciona bien, siempre que la presión no sea demasiado alta ni la temperatura demasiado baja. Una buena aproximación a un cuerpo negro que se puede utilizar para observar la radiación de cuerpo negro es un horno metálico que se pueda calentar a temperaturas muy altas. El horno tiene un pequeño orificio que permite observar la luz que se emite en su interior con un espectrómetro a fin de medir las longitudes de onda y sus intensidades. La muestra las curvas resultantes para algunas temperaturas representativas. Cada distribución depende de un solo parámetro: la temperatura. Los máximos de las curvas del cuerpo negro, λmáx., se desplazan a longitudes de onda más cortas a medida que aumenta la temperatura, lo que refleja la observación de que los metales que se calientan a altas temperaturas comienzan a brillar con un rojo más oscuro que se vuelve más brillante a medida que aumenta la temperatura, llegando a ser blanco a temperaturas muy altas, ya que las intensidades de todas las longitudes de onda visibles se vuelven apreciables. Esta observación común fue el núcleo de la primera paradoja que mostró las limitaciones fundamentales de la física clásica que examinaremos.
Los físicos dedujeron expresiones matemáticas para las curvas del cuerpo negro utilizando conceptos bien aceptados de las teorías de la mecánica clásica y el electromagnetismo clásico. Las expresiones teóricas como funciones de la temperatura se ajustan bien a las curvas experimentales del cuerpo negro observadas en las longitudes de onda más largas, pero muestran discrepancias significativas en las longitudes de onda más cortas. Las curvas teóricas no solo no mostraban un pico, sino que mostraban absurdamente que la intensidad se hacía infinitamente grande a medida que la longitud de onda se hacía más pequeña, lo que implicaría que los objetos cotidianos a temperatura ambiente deberían emitir grandes cantidades de luz ultravioleta. Esto se conoció como la "catástrofe ultravioleta" porque nadie pudo encontrar ningún problema en el tratamiento teórico que pudiera llevar a un comportamiento tan poco realista en la longitud de onda corta. Finalmente, hacia 1900, Max Planck dedujo una expresión teórica para la radiación de cuerpo negro que se ajustaba exactamente a las observaciones experimentales (dentro del error experimental). Planck desarrolló su tratamiento teórico ampliando los trabajos anteriores que se habían basado en la premisa de que los átomos que componen el horno vibraban a frecuencias crecientes (o longitudes de onda decrecientes) a medida que aumentaba la temperatura, siendo estas vibraciones la fuente de la radiación electromagnética emitida. Pero, mientras que los tratamientos anteriores habían permitido que los átomos vibrantes tuvieran cualquier valor de energía que se dedujo a partir de un conjunto continuo de energías (perfectamente razonable, según la física clásica), Planck descubrió que al restringir las energías vibratorias a valores discretos para cada frecuencia, podía deducir una expresión para la radiación de cuerpo negro que tenía correctamente la intensidad cayendo rápidamente en las longitudes de onda cortas de la región UV.
La cantidad h es una constante que ahora se conoce como la constante de Planck, en su honor. Aunque Planck se alegró de haber resuelto la paradoja de la radiación de cuerpo negro, le molestaba que para ello tuviera que suponer que los átomos vibrantes requerían energías cuantizadas, algo que no pudo explicar. El valor de la constante de Planck es muy pequeño, 6,626 10−34 julio segundo (J s), lo que ayuda a explicar por qué la cuantización de la energía no se había observado anteriormente en los fenómenos macroscópicos.
### El efecto fotoeléctrico
La siguiente paradoja de la teoría clásica que había que resolver se refería al efecto fotoeléctrico (). Se había observado que los electrones podían ser expulsados de la superficie limpia de un metal cuando se proyectaba sobre ella una luz con una frecuencia superior a algún umbral. Sorprendentemente, la energía cinética de los electrones expulsados no dependía del brillo de la luz, sino que aumentaba con el incremento de la frecuencia de la luz. Dado que los electrones del metal tenían cierta energía de enlace que los mantenía allí, la luz incidente debía tener más energía para liberar los electrones. Según la teoría clásica de las ondas, la energía de una onda depende de su intensidad (que depende de su amplitud), no de su frecuencia. Parte de estas observaciones fue que el número de electrones expulsados en un periodo de tiempo determinado aumentaba a medida que aumentaba la luminosidad. En 1905, Albert Einstein pudo resolver la paradoja incorporando los hallazgos de cuantización de Planck a la desacreditada visión de la luz como partícula (Einstein ganó realmente su premio Nobel por este trabajo y no por sus teorías de la relatividad por las que es más famoso).
Einstein argumentó que las energías cuantizadas que Planck había postulado en su tratamiento de la radiación de cuerpo negro podían aplicarse a la luz en el efecto fotoeléctrico, de modo que la luz que incidía en la superficie metálica no debía verse como una onda, sino como un flujo de partículas (más tarde llamadas fotones) cuya energía dependía de su frecuencia, según la fórmula de Planck, E = hν (o, en términos de longitud de onda utilizando c = νλ, ). Los electrones eran expulsados cuando fotones con suficiente energía los golpeaban (una frecuencia superior al umbral). Cuanto mayor sea la frecuencia, mayor será la energía cinética impartida a los electrones que escapan por las colisiones. Einstein también argumentó que la intensidad de la luz no dependía de la amplitud de la onda entrante, sino que correspondía al número de fotones que incidían en la superficie en un periodo de tiempo determinado. Esto explica por qué el número de electrones expulsados aumenta con el incremento de la luminosidad, ya que cuanto mayor es el número de fotones entrantes, mayor es la probabilidad de que colisionen con algunos de los electrones.
Con los descubrimientos de Einstein, la naturaleza de la luz adquirió un nuevo aire de misterio. Aunque muchos fenómenos de la luz podían explicarse en términos de ondas o de partículas, algunos fenómenos, como los patrones de interferencia obtenidos cuando la luz pasa a través de una doble rendija, eran completamente contrarios a una visión de partículas de la luz, mientras que otros fenómenos, como el efecto fotoeléctrico, eran completamente contrarios a una visión de ondas de la luz. De alguna manera, en un nivel fundamental profundo que aún no se comprende del todo, la luz es a la vez onda y partícula. Esto se conoce como dualidad onda-partícula.
### Espectros de líneas
Otra paradoja dentro de la teoría electromagnética clásica con la que lucharon los científicos a finales del siglo XIX tenía que ver con la luz emitida por los átomos y las moléculas. Cuando los sólidos, líquidos o gases condensados se calientan lo suficiente, irradian parte del exceso de energía en forma de luz. Los fotones producidos de esta manera tienen un rango de energías y, por lo tanto, producen un espectro continuo en el que está presente una serie ininterrumpida de longitudes de onda. La mayor parte de la luz generada por las estrellas (entre ellas, nuestro Sol) se produce de esta manera. Se pueden ver todas las longitudes de onda visibles de la luz solar utilizando un prisma para separarlas. Como puede verse en la , la luz solar también contiene luz ultravioleta (longitudes de onda más cortas) y luz infrarroja (longitudes de onda más largas), que pueden detectarse con instrumentos, pero que son invisibles para el ojo humano. Los sólidos incandescentes (que brillan), como los filamentos de tungsteno de las luces incandescentes, también emiten luz que contiene todas las longitudes de onda de la luz visible. Estos espectros continuos pueden aproximarse a menudo mediante curvas de radiación de cuerpo negro a alguna temperatura adecuada, como las que se muestran en la .
A diferencia de los espectros continuos, la luz también puede presentarse en forma de espectros discretos o espectros de líneas o con anchos de línea muy estrechos intercalados en las regiones espectrales, como los que se muestran en la . Si se excita un gas a baja presión parcial usando una corriente eléctrica, o si se calienta, producirá espectros de líneas. Las bombillas fluorescentes y los carteles de neón funcionan así (). Cada elemento muestra su propio conjunto característico de líneas, al igual que las moléculas, aunque sus espectros suelen ser mucho más complicados.
Cada línea de emisión consta de una sola longitud de onda de luz, lo que implica que la luz emitida por un gas consta de un conjunto de energías discretas. Por ejemplo, cuando una descarga eléctrica atraviesa un tubo que contiene hidrógeno gaseoso a baja presión, las moléculas de H2 se rompen en átomos de H separados y vemos un color azul-rosado. Cuando la luz pasa través de un prisma se obtiene un espectro de líneas, lo que indica que está compuesta por fotones de cuatro longitudes de onda visibles, como se muestra en la .
El origen de los espectros discretos en los átomos y las moléculas era extremadamente desconcertante para los científicos de finales del siglo XIX ya que, según la teoría electromagnética clásica, solo deberían observarse espectros continuos. Aún más desconcertante, en 1885, Johann Balmer fue capaz de deducir una ecuación empírica que relacionaba las cuatro longitudes de onda visibles de la luz emitida por los átomos de hidrógeno con números enteros. Esa ecuación es la siguiente, en la que k es una constante:
Se encontraron otras líneas discretas para el átomo de hidrógeno en las regiones UV e IR. Johannes Rydberg generalizó el trabajo de Balmer y desarrolló una fórmula empírica que predecía todas las líneas de emisión del hidrógeno, no solo las restringidas al rango visible, donde, n1 y n2 son números enteros, n1 < n2, y es la constante de Rydberg (1,097 107 m−1).
Ya a finales del siglo XIX, la espectroscopia era una ciencia muy precisa, por lo que las longitudes de onda del hidrógeno se medían con gran exactitud, lo que implicaba que la constante de Rydberg también podía determinarse con gran precisión. En su momento, parecía asombroso que una fórmula tan sencilla como la de Rydberg pudiera dar cuenta de mediciones tan precisas, pero fue la explicación final de los espectros de emisión por parte de Neils Bohr en 1913 la que acabó por convencer a los científicos de que debían abandonar la física clásica e impulsó el desarrollo de la mecánica cuántica moderna.
### Conceptos clave y resumen
La luz y otras formas de radiación electromagnética se mueven en el vacío con una velocidad constante, c, de 2,998 108 m s−1. Esta radiación tiene un comportamiento ondulatorio, que puede caracterizarse por una frecuencia, ν, y una longitud de onda, λ, de forma que c = λν. La luz es un ejemplo de onda viajera. Otros fenómenos ondulatorios importantes son las ondas estacionarias, las oscilaciones periódicas y las vibraciones. Las ondas estacionarias presentan cuantización, ya que sus longitudes de onda están limitadas a múltiplos enteros discretos de algunas longitudes características. La radiación electromagnética que pasa a través de dos rendijas estrechamente espaciadas que tienen dimensiones aproximadamente similares a la longitud de onda mostrará un patrón de interferencia que es el resultado de la interferencia constructiva y destructiva de las ondas. La radiación electromagnética también muestra las propiedades de las partículas llamadas fotones. La energía de un fotón está relacionada con la frecuencia (o alternativamente, la longitud de onda) de la radiación como E = hν (o ), donde h es la constante de Planck. El hecho de que la luz tenga un comportamiento tanto de onda como de partícula se conoce como dualidad onda-partícula. Todas las formas de radiación electromagnética comparten estas propiedades, aunque varias formas, como los rayos X, la luz visible, las microondas y las ondas de radio, interactúan de forma diferente con la materia y tienen aplicaciones prácticas muy distintas. La radiación electromagnética puede generarse excitando la materia a energías más altas, por ejemplo, calentándola. La luz emitida puede ser continua (fuentes incandescentes como el Sol) o discreta (de tipos específicos de átomos excitados). Los espectros continuos suelen tener distribuciones que pueden aproximarse a la radiación de cuerpo negro a una temperatura adecuada. El espectro de líneas del hidrógeno se obtiene al hacer pasar la luz de un tubo electrificado de gas hidrógeno a través de un prisma. Este espectro de líneas era lo suficientemente sencillo como para poder deducir del mismo una fórmula empírica denominada fórmula de Rydberg. Tres paradojas históricamente importantes de finales del siglo XIX y principios del XX que no podían explicarse dentro del marco existente de la mecánica clásica y el electromagnetismo clásico eran el problema del cuerpo negro, el efecto fotoeléctrico y los espectros discretos de los átomos. La resolución de estas paradojas condujo finalmente a las teorías cuánticas que sustituyeron a las clásicas.
### Ecuaciones clave
### Ejercicios de fin de capítulo de Química
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# Estructura electrónica y propiedades periódicas de los elementos
## El modelo de Bohr
Tras los trabajos de Ernest Rutherford y sus colegas a principios del siglo XX, estaba bien establecida la idea de que los átomos están formados por pequeños núcleos densos rodeados de electrones más ligeros y aun más pequeños que se mueven continuamente alrededor del núcleo. Esta imagen se denominó modelo planetario, ya que imaginaba el átomo como un "sistema solar" en miniatura en el que los electrones orbitaban alrededor del núcleo como los planetas alrededor del Sol. El átomo más simple es el hidrógeno, que consiste en un solo protón como núcleo alrededor del cual se mueve un solo electrón. La fuerza electrostática que atrae al electrón hacia el protón depende únicamente de la distancia entre las dos partículas. Sin embargo, esta descripción mecánica clásica del átomo es incompleta, ya que un electrón que se mueve en una órbita elíptica estaría acelerando (cambiando de dirección) y, según el electromagnetismo clásico, debería emitir continuamente radiación electromagnética. Esta pérdida de energía orbital debería dar lugar a que la órbita del electrón se hiciera cada vez más pequeña hasta entrar en espiral en el núcleo, lo que implica que los átomos son intrínsecamente inestables.
En 1913, Niels Bohr intentó resolver la paradoja atómica ignorando la predicción del electromagnetismo clásico de que el electrón en órbita del hidrógeno emitiría luz continuamente. En cambio, incorporó a la descripción mecánica clásica del átomo las ideas de Planck sobre la cuantización y el hallazgo de Einstein de que la luz está formada por fotones cuya energía es proporcional a su frecuencia. Bohr asumió que el electrón que orbita el núcleo normalmente no emite ninguna radiación (la hipótesis del estado estacionario), pero emitiría o absorbería un fotón si se moviera a una órbita diferente. La energía absorbida o emitida reflejaría las diferencias en las energías orbitales según esta ecuación:
En esta ecuación, h es la constante de Planck, y E y E son las energías orbitales inicial y final, respectivamente. Se utiliza el valor absoluto de la diferencia de energía ya que las frecuencias y las longitudes de onda son siempre positivas. En lugar de permitir valores continuos de energía, Bohr asumió que las energías de estos electrones orbitales estaban cuantizadas:
En esta expresión, k es una constante que comprende constantes fundamentales como la masa y la carga del electrón y la constante de Planck. Insertando la expresión de las energías orbitales en la ecuación de ΔE se obtiene
o
que es idéntica a la ecuación de Rydberg en la que Cuando Bohr calculó su valor teórico para la constante de Rydberg, y lo comparó con el valor aceptado experimentalmente, obtuvo una excelente concordancia. Dado que la constante de Rydberg era una de las constantes que se medían con mayor precisión en aquella época, este nivel de concordancia era asombroso y significaba que el modelo de Bohr se tomaba en serio, a pesar de las muchas suposiciones que Bohr necesitaba para deducirlo.
Los niveles de energía más bajos se muestran en la . Una de las leyes fundamentales de la física es que la materia es más estable con la menor energía posible. Así, el electrón de un átomo de hidrógeno suele moverse en la órbita n = 1, la órbita en la que tiene la menor energía. Cuando el electrón se encuentra en esta órbita de mínima energía, se dice que el átomo está en su estado fundamental electrónico (o simplemente estado fundamental). Si el átomo recibe energía de una fuente externa, es posible que el electrón se mueva a una órbita con un valor n más alto y el átomo se encuentra ahora en un estado electrónico excitado (o simplemente un estado excitado) con una energía más alta. Cuando un electrón pasa de un estado excitado (órbita de mayor energía) a un estado menos excitado, o estado fundamental, la diferencia de energía se emite en forma de fotón. Del mismo modo, si un fotón es absorbido por un átomo, la energía del fotón hace que un electrón pase de una órbita de menor energía a otra más excitada. Podemos relacionar la energía de los electrones en los átomos con lo que hemos aprendido anteriormente sobre la energía. La ley de conservación de energía dice que no podemos crear ni destruir energía. Así, si se requiere una cierta cantidad de energía externa para excitar un electrón de un nivel energético a otro, esa misma cantidad de energía se liberará cuando el electrón vuelva a su estado inicial ().
Dado que el modelo de Bohr implicaba un solo electrón, también podía aplicarse a los iones de un solo electrón de He+, Li2+, Be3+, etc., que solo se diferencian del hidrógeno en sus cargas nucleares, por lo que los átomos e iones de un solo electrón se denominan colectivamente átomos hidrogenoides. La expresión de energía para los átomos hidrogenoides es una generalización de la energía del átomo de hidrógeno, en la que Z es la carga nuclear (+1 para el hidrógeno, +2 para el He, +3 para el Li, etc.) y k tiene un valor de 2,179 10-18 J.
Los tamaños de las órbitas circulares para los átomos hidrogenoides vienen dados en términos de sus radios por la siguiente expresión, en la que es una constante llamada radio de Bohr, con un valor de 5,292 10−11 m:
La ecuación también nos muestra que a medida que aumenta la energía del electrón (al aumentar n), el electrón se encuentra a mayores distancias del núcleo. Esto se deduce de la dependencia inversa de la atracción electrostática con respecto a la distancia, ya que, a medida que el electrón se aleja del núcleo, la atracción electrostática entre él y el núcleo disminuye y se mantiene con menos fuerza en el átomo. Observe que a medida que n aumenta y las órbitas se hacen más grandes, sus energías se acercan a cero, por lo que los límites y quieren decir que E = 0 corresponde al límite de ionización en el que el electrón se aleja completamente del núcleo. Así, para el hidrógeno en estado fundamental n = 1, la energía de ionización sería:
Una vez resueltas las tres paradojas extremadamente desconcertantes (la radiación de cuerpo negro, el efecto fotoeléctrico y el átomo de hidrógeno), y todas ellas relacionadas con la constante de Planck de manera fundamental, la mayoría de los físicos de la época vieron claro que las teorías clásicas que funcionaban tan bien en el mundo macroscópico eran fundamentalmente defectuosas y no podían extenderse hasta el dominio microscópico de los átomos y las moléculas. Desgraciadamente, a pesar del notable logro de Bohr al obtener una expresión teórica para la constante de Rydberg, fue incapaz de extender su teoría al siguiente átomo más simple, el He, que solo tiene dos electrones. El modelo de Bohr era muy defectuoso, ya que todavía se basaba en la noción de la mecánica clásica de órbitas precisas, un concepto que más tarde se descubrió que era insostenible en el dominio microscópico cuando se desarrolló un modelo propio de mecánica cuántica para sustituir a la mecánica clásica.
El modelo de Bohr del átomo de hidrógeno permite comprender el comportamiento de la materia a nivel microscópico, pero no explica las interacciones electrón-electrón en los átomos con más de un electrón. Introduce varias características importantes de todos los modelos utilizados para describir la distribución de electrones en un átomo. Entre estas características se encuentran las siguientes:
1. Las energías de los electrones (niveles de energía) en un átomo están cuantizadas, descritas por números cuánticos: números enteros que solo tienen un valor específico permitido y que se utilizan para caracterizar la disposición de los electrones en un átomo.
2. La energía de un electrón aumenta con la distancia al núcleo.
3. Las energías discretas (líneas) en los espectros de los elementos son el resultado de energías electrónicas cuantizadas.
De estas características, la más importante es el postulado de los niveles de energía cuantizados para un electrón en un átomo. Como consecuencia, el modelo sentó las bases del modelo mecánico cuántico del átomo. Bohr obtuvo el Premio Nobel de Física por sus contribuciones a la comprensión de la estructura de los átomos y su relación con las emisiones de los espectros de líneas.
### Conceptos clave y resumen
Bohr incorporó las ideas de cuantización de Planck y Einstein en un modelo del átomo de hidrógeno que resolvía la paradoja de la estabilidad del átomo y los espectros discretos. El modelo de Bohr del átomo de hidrógeno explica la conexión entre la cuantización de los fotones y la emisión cuantizada de los átomos. Bohr describió el átomo de hidrógeno en términos de un electrón que se mueve en una órbita circular alrededor de un núcleo. Postuló que el electrón estaba restringido a ciertas órbitas caracterizadas por energías discretas. Las transiciones entre estas órbitas permitidas dan lugar a la absorción o emisión de fotones. Cuando un electrón pasa de una órbita de mayor energía a otra más estable, se emite energía en forma de fotón. Para que un electrón pase de una órbita estable a otra más excitada, hay que absorber un fotón de energía. Utilizando el modelo de Bohr, podemos calcular la energía de un electrón y el radio de su órbita en cualquier sistema de un electrón.
### Ecuaciones clave
### Ejercicios de química del final del capítulo
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# Estructura electrónica y propiedades periódicas de los elementos
## Desarrollo de la teoría cuántica
El modelo de Bohr explicaba los datos experimentales del átomo de hidrógeno y era ampliamente aceptado, pero también planteaba muchas interrogantes. ¿Por qué los electrones solo orbitan a distancias fijas definidas por un único número cuántico n = 1, 2, 3, etc., pero nunca entre ellos? ¿Por qué el modelo funcionó tan bien describiendo el hidrógeno y los iones de un electrón, pero no pudo predecir correctamente el espectro de emisión del helio o de cualquier otro átomo más grande? Para responder estas preguntas, los científicos tuvieron que revisar por completo su forma de pensar sobre la materia.
### Comportamiento en el mundo microscópico
Sabemos cómo se comporta la materia en el mundo macroscópico: los objetos lo suficientemente grandes como para ser vistos a simple vista siguen las reglas de la física clásica. Una bola de billar que se mueve en una mesa se comportará como una partícula: continuará en línea recta a menos que choque con otra bola o con el cojín de la mesa, o que actúe sobre ella alguna otra fuerza (como la fricción). La bola tiene una posición y una velocidad bien definidas (o un momento bien definido, p = mv, definido por la masa m y la velocidad v) en cualquier momento. En otras palabras, la bola se mueve en una trayectoria clásica. Este es el comportamiento típico de un objeto clásico.
Cuando las ondas interactúan entre sí, muestran patrones de interferencia que no muestran las partículas macroscópicas, como la bola de billar. Por ejemplo, las ondas que interactúan en la superficie del agua pueden producir patrones de interferencia similares a los que se muestran en la . Este es un caso de comportamiento ondulatorio a escala macroscópica, y está claro que las partículas y las ondas son fenómenos muy diferentes en el ámbito macroscópico.
A medida que las mejoras tecnológicas permitieron a los científicos explorar el mundo microscópico con mayor detalle, en la década de 1920 quedó cada vez más claro que las piezas muy pequeñas de la materia siguen un conjunto de reglas diferentes a las que observamos para los objetos grandes. La incuestionable separación de las ondas y las partículas ya no es el caso del mundo microscópico.
Uno de los primeros en prestar atención al comportamiento especial del mundo microscópico fue Louis De Broglie. Hizo la pregunta: Si la radiación electromagnética puede tener carácter de partícula, ¿pueden los electrones y otras partículas submicroscópicas presentar carácter de onda? En su tesis doctoral de 1925, De Broglie extendió la dualidad onda-partícula de la luz que Einstein utilizó para resolver la paradoja del efecto fotoeléctrico a las partículas materiales. Predijo que una partícula con masa m y velocidad v (es decir, con momento lineal p) también debería mostrar el comportamiento de una onda con un valor de longitud de onda λ, dado por esta expresión en la que h es la conocida constante de Planck:
Esto se llama la longitud de onda de De Broglie. A diferencia de los otros valores de λ que se analizan en este capítulo, la longitud de onda de De Broglie es una característica de las partículas y otros cuerpos, no de la radiación electromagnética (nótese que esta ecuación involucra la velocidad [v, m/s], no la frecuencia [ν, Hz]. Aunque estos dos símbolos parecen casi idénticos, significan cosas muy diferentes). Mientras que Bohr había postulado que el electrón era una partícula que orbitaba alrededor del núcleo en órbitas cuantizadas, De Broglie argumentó que el supuesto de cuantización de Bohr puede explicarse si el electrón se considera no como una partícula, sino como una onda estacionaria circular tal que solo un número entero de longitudes de onda podría caber exactamente dentro de la órbita ().
Para una órbita circular de radio r, la circunferencia es 2πr, por lo que la condición de De Broglie es:
Poco después de que De Broglie propusiera la naturaleza ondulatoria de la materia, dos científicos de los Laboratorios Bell, C. J. Davisson y L. H. Germer, demostraron experimentalmente que los electrones pueden mostrar un comportamiento ondulatorio al mostrar un patrón de interferencia para los electrones que viajan a través de un patrón atómico regular en un cristal. Capas atómicas regularmente espaciadas en forma de rendijas, como las utilizadas en otros experimentos de interferencia. Dado que el espacio entre las capas en forma de rendijas debe ser similar en tamaño a la longitud de onda de la onda probada para que se forme un patrón de interferencia, Davisson y Germer utilizaron un blanco de níquel cristalino para sus "rendijas", ya que el espacio de los átomos dentro de la red era aproximadamente el mismo que las longitudes de onda de De Broglie de los electrones que utilizaron. La muestra un patrón de interferencia. Es sorprendentemente similar a los patrones de interferencia de la luz mostrados en Energía Electromagnética para la luz que pasa a través de dos rendijas estrechas muy próximas entre sí. La dualidad onda-partícula de la materia puede verse en la observando lo que ocurre si se registran las colisiones de electrones durante un largo periodo de tiempo. Inicialmente, cuando solo se habían registrado unos pocos electrones, estos muestran un claro comportamiento similar al de las partículas, habiendo llegado en pequeños paquetes localizados que parecen ser aleatorios. A medida que llegaban más y más electrones y se registraban, surgía un claro patrón de interferencia que es el sello del comportamiento ondulatorio. Así parece que, aunque los electrones son pequeñas partículas localizadas, su movimiento no sigue las ecuaciones de movimiento implicadas por la mecánica clásica, sino que se rige por algún tipo de ecuación de onda. De esta forma, la dualidad onda-partícula observada por primera vez con los fotones es en realidad un comportamiento fundamental intrínseco a todas las partículas cuánticas.
Werner Heisenberg consideró los límites de la precisión con la que podemos medir las propiedades de un electrón u otras partículas microscópicas. Determinó que existe un límite fundamental a la precisión con la que se puede medir simultáneamente la posición y el momento de una partícula. Cuanto más exactamente midamos el momento de una partícula, menos exactamente podremos determinar su posición en ese momento, y viceversa. Esto se resume en lo que ahora llamamos el principio de incertidumbre de Heisenberg: es fundamentalmente imposible determinar simultáneamente y con exactitud tanto el momento como la posición de una partícula. Para una partícula de masa m que se mueve con la velocidad v en la dirección x (o equivalentemente con el momento px), el producto de la incertidumbre en la posición, Δx, y la incertidumbre en el momento, Δp, debe ser mayor o igual a (donde el valor de la constante de Planck dividido entre 2π).
Esta ecuación nos permite calcular el límite de la precisión con la que podemos conocer tanto la posición simultánea de un objeto como su momento. Por ejemplo, si mejoramos nuestra medición de la posición de un electrón para que la incertidumbre en la posición (Δx) tenga un valor de, digamos, 1 pm (10-12 m, aproximadamente el 1% del diámetro de un átomo de hidrógeno), entonces nuestra determinación de su momento debe tener una incertidumbre con un valor de al menos
El valor de ħ no es grande, por lo que la incertidumbre en la posición o el momento de un objeto macroscópico como una pelota de béisbol es demasiado insignificante para ser observada. Sin embargo, la masa de un objeto microscópico como un electrón es lo suficientemente pequeña como para que la incertidumbre pueda ser grande y significativa.
Cabe señalar que el principio de incertidumbre de Heisenberg no se limita a las incertidumbres de posición y momento, sino que también relaciona otras variables dinámicas. Por ejemplo, cuando un átomo absorbe un fotón y realiza una transición de un estado energético a otro, la incertidumbre en la energía y la incertidumbre en el tiempo requerido para la transición están relacionadas de forma similar, ya que ΔE Δt ≥
El principio de Heisenberg impone límites máximos a lo que se puede conocer en la ciencia. Se puede demostrar que el principio de incertidumbre es una consecuencia de la dualidad onda-partícula, que está en el centro de lo que distingue a la teoría cuántica moderna de la mecánica clásica.
### El modelo mecánico-cuántico de un átomo
Poco después de que De Broglie publicara sus ideas de que el electrón de un átomo de hidrógeno podía considerarse mejor como una onda estacionaria circular en lugar de una partícula que se mueve en órbitas circulares cuantizadas, Erwin Schrödinger amplió el trabajo de De Broglie derivando lo que hoy se conoce como la ecuación de Schrödinger. Cuando Schrödinger aplicó su ecuación a los átomos hidrogenoides pudo reproducir la expresión de Bohr para la energía y, por tanto, la fórmula de Rydberg que rige los espectros del hidrógeno. Schrödinger describió los electrones como ondas estacionarias tridimensionales, o funciones de onda, representadas por la letra griega psi, ψ. Unos años más tarde, Max Born propuso una interpretación de la función de onda ψ que sigue siendo aceptada en la actualidad: Los electrones siguen siendo partículas, por lo que las ondas representadas por ψ no son ondas físicas, sino amplitudes de probabilidad complejas. El cuadrado de la magnitud de una función de onda describe la probabilidad de que la partícula cuántica esté presente cerca de un lugar determinado del espacio. Esto significa que las funciones de onda pueden utilizarse para determinar la distribución de la densidad del electrón con respecto al núcleo en un átomo. En la forma más general, la ecuación de Schrödinger puede escribirse como:
es el operador hamiltoniano, un conjunto de operaciones matemáticas que representan la energía total de la partícula cuántica (como un electrón en un átomo), ψ es la función de onda de esta partícula que puede utilizarse para encontrar la distribución especial de la probabilidad de encontrar la partícula, y es el valor real de la energía total de la partícula.
El trabajo de Schrödinger, así como el de Heisenberg y muchos otros científicos que siguieron sus pasos, se conoce generalmente como mecánica cuántica.
### Comprensión de la teoría cuántica de los electrones en los átomos
El objetivo de esta sección es comprender los electrones orbitales (ubicación de los electrones en los átomos), sus diferentes energías y otras propiedades. El uso de la teoría cuántica proporciona la mejor comprensión de estos temas. Este conocimiento es un precursor del enlace químico.
Como se ha descrito anteriormente, los electrones de los átomos solo pueden existir en niveles de energía discretos, pero no entre ellos. Se dice que la energía de un electrón en un átomo está cuantizada, es decir, solo puede ser igual a ciertos valores específicos y puede saltar de un nivel de energía a otro, pero no hacer una transición suave o permanecer entre estos niveles.
Los niveles de energía se etiquetan con un valor n, donde n = 1, 2, 3,... En general, la energía de un electrón en un átomo es mayor para valores mayores de n. Este número, n, se denomina número cuántico principal. El número cuántico principal define la ubicación del nivel de energía. Es esencialmente el mismo concepto que n en la descripción del átomo de Bohr. Otro nombre para el número cuántico principal es el número de capa. Las capas de un átomo pueden considerarse círculos concéntricos que irradian desde el núcleo. Los electrones que pertenecen a una capa específica tienen más probabilidades de encontrarse dentro del área circular correspondiente. Cuanto más nos alejamos del núcleo, mayor es el número de capa y, por tanto, mayor es el nivel de energía (). Los protones cargados positivamente en el núcleo estabilizan los electrones orbitales mediante la atracción electrostática entre las cargas positivas de los protones y las cargas negativas de los electrones. Así, cuanto más lejos esté el electrón del núcleo, mayor será su energía.
Este modelo de mecánica cuántica para determinar dónde residen los electrones en un átomo puede utilizarse para observar las transiciones electrónicas, es decir, los acontecimientos en los que un electrón pasa de un nivel de energía a otro. Si la transición es a un nivel de energía superior, se absorbe energía y el cambio de energía tiene un valor positivo. Para obtener la cantidad de energía necesaria para la transición a un nivel energético superior, el átomo absorbe un fotón. Una transición a un nivel de energía inferior implica una liberación de energía y el cambio de energía es negativo. Este proceso va acompañado de la emisión de un fotón por parte del átomo. La siguiente ecuación resume estas relaciones y se basa en el átomo de hidrógeno:
Los valores nf y ni son los estados de energía final e inicial del electrón. El en la sección anterior del capítulo demuestra los cálculos de dichos cambios de energía.
El número cuántico principal es uno de los tres números cuánticos utilizados para caracterizar un orbital. Un orbital atómico es una región general en un átomo dentro de la cual es más probable que resida un electrón. El modelo mecánico cuántico especifica la probabilidad de encontrar un electrón en el espacio tridimensional alrededor del núcleo y se basa en las soluciones de la ecuación de Schrödinger. Además, el número cuántico principal define la energía de un electrón en un átomo de hidrógeno o átomos hidrogenoides o en un ion (un átomo o un ion con un solo electrón) y la región general en la que se encuentran los niveles de energía discretos de los electrones en los átomos e iones multielectrónicos.
Otro número cuántico es l, el número cuántico secundario (de momento angular). Es un número entero que puede tomar los valores, l = 0, 1, 2,..., n - 1. Esto significa que un orbital con n = 1 solo puede tener un valor de l, l = 0, mientras que n = 2 permite l = 0 y l = 1, y así sucesivamente. Mientras que el número cuántico principal, n, define el tamaño general y la energía del orbital, el número cuántico secundario l especifica la forma del orbital. Los orbitales con el mismo valor de l definen una subcapa.
Los orbitales con l = 0 se denominan orbitales y constituyen las subcapas s. El valor l = 1 corresponde a los orbitales p. Para un n dado, los orbitales constituyen una subcapa p (por ejemplo, 3p si n = 3). Los orbitales con l = 2 se denominan orbitales , seguidos de los orbitales f, g, y h para l = 3, 4 y 5.
Hay ciertas distancias del núcleo a las que la densidad de probabilidad de encontrar un electrón situado en un orbital concreto es cero. En otras palabras, el valor de la función de onda ψ es cero a esta distancia para este orbital. Este valor de radio r se denomina nodo radial. El número de nodos radiales en un orbital es n - l - 1.
Considere los ejemplos de la . Los orbitales representados son del tipo s, por lo que l = 0 para todos ellos. Se puede ver en los gráficos de las densidades de probabilidad que hay 1 – 0 – 1 = 0 lugares donde la densidad es cero (nodos) para el 1s (n = 1), 2 – 0 – 1 = 1 nodo para el 2s, y 3 – 0 – 1 = 2 nodos para los orbitales 3s.
La distribución de la configuración electrónica de la subcapa s es esférica y la subcapa p tiene forma de campana. Los orbitales d y más complejos. Estas formas representan las regiones tridimensionales en las que es probable que se encuentre el electrón.
El número cuántico magnético, m, especifica la orientación espacial relativa de un orbital concreto. En general, m puede ser igual a –l, –(l – 1),…, 0,…, (l – 1), l. El número total de orbitales posibles con el mismo valor de l (es decir, en la misma subcapa) es 2l + 1. Así, hay un orbital s en una subcapa s (l = 0), hay tres orbitales p en una subcapa p (l = 1), cinco orbitales d en una subcapa d (l = 2), siete orbitales f en una subcapa f (l = 3), etc. El número cuántico principal define el valor general de la energía electrónica. El número cuántico del momento angular determina la forma del orbital. Y el número cuántico magnético especifica la orientación del orbital en el espacio, como puede verse en la .
La ilustra los niveles de energía de varios orbitales. El número que precede al nombre del orbital (como 2s, 3p, etc.) representa el número cuántico principal, n. La letra en el nombre del orbital define la subcapa con un número cuántico de momento angular específico l = 0 para los orbitales s, 1 para los orbitales p, 2 para los orbitales d. Por último, hay más de un orbital posible para l ≥ 1, cada uno correspondiente a un valor específico de m. En el caso de un átomo de hidrógeno o un ion de un solo electrón (como He+, Li2+, etc.), las energías de todos los orbitales con el mismo n son iguales. Esto se llama degeneración, y los niveles de energía para el mismo número cuántico principal, n, se llaman orbitales degenerados. Sin embargo, en los átomos con más de un electrón, esta degeneración es eliminada por las interacciones electrón-electrón y los orbitales que pertenecen a diferentes subcapas tienen energías diferentes, como se muestra en la . Los orbitales dentro de la misma subcapa siguen siendo degenerados y tienen la misma energía.
Aunque los tres números cuánticos discutidos en los párrafos anteriores funcionan bien para describir los orbitales de los electrones, algunos experimentos mostraron que no eran suficientes para explicar todos los resultados observados. En la década de 1920 se demostró que cuando se examinan los espectros de líneas de hidrógeno con una resolución extremadamente alta, algunas líneas no son en realidad picos únicos, sino más bien pares de líneas estrechamente espaciadas. Esta es la llamada estructura fina del espectro, e implica que hay pequeñas diferencias adicionales en las energías de los electrones, incluso cuando se encuentran en el mismo orbital. Estas observaciones llevaron a Samuel Goudsmit y George Uhlenbeck a proponer que los electrones tienen un cuarto número cuántico. Lo llamaron el número cuántico de espín, o .
Los otros tres números cuánticos, n, l y m, son propiedades de orbitales atómicos específicos que también definen en qué parte del espacio es más probable que se encuentre un electrón. Los orbitales son el resultado de resolver la ecuación de Schrödinger para los electrones de los átomos. El espín del electrón es una propiedad diferente. Es un fenómeno completamente cuántico sin análogos en el ámbito clásico. Además, no puede deducirse de la resolución de la ecuación de Schrödinger y no está relacionada con las coordenadas espaciales normales (como las cartesianas x, y y z). El espín del electrón describe una "rotación" o "giro" intrínseca del electrón. Cada electrón actúa como un minúsculo imán o un diminuto objeto giratorio con un momento angular, o como un bucle con una corriente eléctrica, aunque esta rotación o corriente no pueda observarse en términos de coordenadas espaciales.
La magnitud del espín global del electrón solo puede tener un valor, y un electrón solo puede "girar" (espín) en uno de los dos estados cuantizados. Uno de ellos se denomina estado α, con la componente z del espín en la dirección positiva del eje z. Esto corresponde al número cuántico de espín El otro se denomina estado β, siendo la componente z del espín negativa y Cualquier electrón, independientemente del orbital atómico en el que se encuentre, solo puede tener uno de esos dos valores del número cuántico de espín. Las energías de los electrones que tienen y son diferentes si se aplica un campo magnético externo.
La ilustra este fenómeno. Un electrón actúa como un pequeño imán. Su momento se dirige hacia arriba (en la dirección positiva del eje z) para el número cuántico de espín y hacia abajo (en la dirección z negativa) para el número cuántico de espín de Un imán tiene una energía menor si su momento magnético está alineado con el campo magnético externo (el electrón de la izquierda en la ) y una energía mayor para el momento magnético opuesto al campo aplicado. Por ello, un electrón con tiene una energía ligeramente inferior en un campo externo en la dirección z positiva, y un electrón con tiene una energía ligeramente superior en el mismo campo. Esto es cierto incluso para un electrón que ocupa el mismo orbital en un átomo. Una línea espectral correspondiente a una transición para electrones del mismo orbital, pero con números cuánticos de espín diferentes, tiene dos valores posibles de energía; por lo tanto, la línea en el espectro mostrará una división de la estructura fina.
### El principio de exclusión de Pauli
Un electrón en un átomo se describe completamente mediante cuatro números cuánticos: n, l, m y m. Los tres primeros números cuánticos definen el orbital y el cuarto número cuántico describe la propiedad intrínseca del electrón llamada espín. El físico austriaco Wolfgang Pauli formuló un principio general que proporciona la última información que necesitamos para comprender el comportamiento general de los electrones en los átomos. El principio de exclusión de Pauli puede formularse como sigue: no hay dos electrones en el mismo átomo que puedan tener exactamente el mismo conjunto de los cuatro números cuánticos. Esto significa que dos electrones pueden compartir el mismo orbital (el mismo conjunto de números cuánticos n, l y m) solo si sus números cuánticos de espín m tienen valores diferentes. Como el número cuántico de espín solo puede tener dos valores no más de dos electrones pueden ocupar el mismo orbital (y si dos electrones se encuentran en el mismo orbital, deben tener espines opuestos). Por lo tanto, cualquier orbital atómico puede estar poblado solo por cero, uno o dos electrones.
Las propiedades y el significado de los números cuánticos de los electrones en los átomos se resumen brevemente en la .
### Conceptos clave y resumen
Los objetos macroscópicos actúan como partículas. Los objetos microscópicos (como los electrones) tienen propiedades tanto de partícula como de onda. No se puede determinar su trayectoria exacta. El modelo mecánico cuántico de los átomos describe la posición tridimensional del electrón de forma probabilística según una función matemática llamada función de onda, a menudo denotada como ψ. Las funciones de onda atómicas también se denominan orbitales. La magnitud al cuadrado de la función de onda describe la distribución de la probabilidad de encontrar el electrón en una región concreta del espacio. Por lo tanto, los orbitales atómicos describen las zonas de un átomo donde es más probable que se encuentren los electrones.
Un orbital atómico se caracteriza por tres números cuánticos. El número cuántico principal, n, puede ser cualquier número entero positivo. La región general para el valor de la energía del orbital y la distancia media de un electrón al núcleo están relacionadas con n. Los orbitales que tienen el mismo valor de n se dice que están en la misma capa. El número cuántico secundario (momento angular), l, puede tener cualquier valor entero de 0 a n - 1. Este número cuántico describe la forma o el tipo de orbital. Los orbitales con el mismo número cuántico principal y el mismo valor l pertenecen a la misma subcapa. El número cuántico magnético, m, con valores 2l + 1 que van de -l a +l, describe la orientación del orbital en el espacio. Además, cada electrón tiene un número cuántico de espín, m, que puede ser igual a No hay dos electrones en el mismo átomo que puedan tener el mismo conjunto de valores para los cuatro números cuánticos.
### Ejercicios de química del final del capítulo
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# Estructura electrónica y propiedades periódicas de los elementos
## Estructura electrónica de los átomos (configuraciones de electrones)
Una vez introducidos los fundamentos de la estructura atómica y la mecánica cuántica, podemos utilizar nuestra comprensión de los números cuánticos para determinar cómo se relacionan los orbitales atómicos entre sí. Esto nos permite determinar qué orbitales están ocupados por electrones en cada átomo. La disposición específica de los electrones en los orbitales de un átomo determina muchas de sus propiedades químicas.
### Energías orbitales y estructura atómica
La energía de los orbitales atómicos aumenta a medida que aumenta el número cuántico principal, n. En cualquier átomo con dos o más electrones, la repulsión entre los electrones hace que las energías de las subcapas con diferentes valores de l difieran, de modo que la energía de los orbitales aumenta dentro de una capa en el orden s < p < d < f. La representa cómo se relacionan estas dos tendencias de aumento de energía. El orbital 1s en la parte inferior del diagrama es el orbital con electrones de menor energía. La energía aumenta a medida que subimos a los orbitales 2s y luego 2p, 3s y 3p, lo que demuestra que el valor creciente de n tiene más influencia en la energía que el valor creciente de l para los átomos pequeños. Sin embargo, este patrón no se mantiene para los átomos más grandes. El orbital 3d tiene mayor energía que el orbital 4s. Este tipo de superposición se siguen produciendo con frecuencia a medida que ascendemos en el gráfico.
Los electrones de los átomos sucesivos de la tabla periódica tienden a llenar primero los orbitales de baja energía. Así, muchos estudiantes encuentran confuso que, por ejemplo, los orbitales 5p se llenen inmediatamente después de los 4d, e inmediatamente antes de los 6s. El orden de llenado se basa en los resultados experimentales observados y se ha confirmado mediante cálculos teóricos. A medida que aumenta el número cuántico principal, n, aumenta el tamaño del orbital y los electrones pasan más tiempo alejados del núcleo. Así, la atracción hacia el núcleo es más débil y la energía asociada al orbital es mayor (menos estabilizada). Pero este no es el único efecto que debemos tener en cuenta. Dentro de cada capa, a medida que aumenta el valor de l, los electrones son menos penetrantes (lo que significa que hay menos configuración electrónica cerca del núcleo), en el orden s > p > d > f. Los electrones que están más cerca del núcleo repelen ligeramente a los electrones que están más lejos, compensando ligeramente las atracciones electrón-núcleo más dominantes (recordemos que todos los electrones tienen cargas -1, pero los núcleos tienen cargas +Z). Este fenómeno se denomina apantallamiento y se analizará con más detalle en la siguiente sección. Los electrones de los orbitales que experimentan un mayor apantallamiento están menos estabilizados y, por tanto, son más energéticos. Para los orbitales pequeños (de 1s a 3p), el aumento de energía debido a n es más significativo que el aumento debido a l; sin embargo, para los orbitales más grandes, las dos tendencias son comparables y no pueden predecirse simplemente. Discutiremos los métodos para recordar el orden observado.
La disposición de los electrones en los orbitales de un átomo se denomina configuración de electrones del átomo. Describimos una configuración de electrones con un símbolo que contiene tres informaciones ():
1. El número de la capa cuántica principal, n,
2. La letra que designa el tipo de orbital (la subcapa, l), y
3. Un número de superíndice que designa el número de electrones en esa subcapa particular.
Por ejemplo, la notación 2p4 (se lee "dos-p-cuatro") indica cuatro electrones en una subcapa p (l = 1) con un número cuántico principal (n) de 2. La notación 3d8 (se lee "tres-d-ocho") indica ocho electrones en la subcapa d (es decir, l = 2) de la capa principal para la que n = 3.
### El principio de Aufbau
Para determinar la configuración de electrones de un átomo en particular, podemos "construir" las estructuras en el orden de los números atómicos. Empezando por el hidrógeno, y continuando a través de los periodos de la tabla periódica, añadimos un protón cada vez al núcleo y un electrón a la subcapa correspondiente hasta que hayamos descrito la configuración de electrones de todos los elementos. Este procedimiento se denomina principio Aufbau, de la palabra alemana Aufbau ("construir"). Cada electrón añadido ocupa la subcapa de menor energía disponible (en el orden indicado en la ), con las limitaciones impuestas por los números cuánticos permitidos según el principio de exclusión de Pauli. Los electrones entran en las subcapas de mayor energía solo después de que las subcapas de menor energía se hayan llenado hasta su capacidad. La ilustra la forma tradicional de recordar el orden de llenado de los orbitales atómicos. Dado que la ordenación de la tabla periódica se basa en la configuración de electrones, la proporciona un método alternativo para determinar la configuración de electrones. El orden de llenado simplemente comienza en el hidrógeno e incluye cada subcapa a medida que se avanza en el orden Z creciente. Por ejemplo, después de llenar el bloque 3p hasta Ar, vemos que el orbital será 4s (K, Ca), seguido por los orbitales 3d.
A continuación construiremos la configuración de electrones del estado fundamental y el diagrama de orbitales para una selección de átomos del primer y segundo periodos de la tabla periódica. Los diagramas de orbitales son representaciones pictóricas de la configuración de electrones, mostrando los orbitales individuales y la disposición de los pares de electrones. Empezamos con un único átomo de hidrógeno (número atómico 1), que consta de un protón y un electrón. Haciendo referencia a la o la , esperaríamos encontrar el electrón en el orbital 1s. Por convención, el valor se suele rellenar primero. La configuración de electrones y el diagrama orbital son:
Después del hidrógeno se encuentra el gas noble helio, que tiene un número atómico de 2. El átomo de helio contiene dos protones y dos electrones. El primer electrón tiene los mismos cuatro números cuánticos que el electrón del átomo de hidrógeno (n = 1, l = 0, m = 0, ). El segundo electrón también entra en el orbital 1s y llena ese orbital. El segundo electrón tiene los mismos números cuánticos n, l y m, pero debe tener el número cuántico de espín opuesto, Esto está de acuerdo con el principio de exclusión de Pauli: no hay dos electrones en el mismo átomo que puedan tener el mismo conjunto de cuatro números cuánticos. Para los diagramas orbitales, esto significa que dos flechas van en cada cuadrado (representando dos electrones en cada orbital) y las flechas deben apuntar en direcciones opuestas (representando espines emparejados). La configuración de electrones y el diagrama orbital del helio son:
La capa n = 1 está completamente llena en un átomo de helio.
El siguiente átomo es el metal alcalino litio con un número atómico de 3. Los dos primeros electrones del litio ocupan el orbital 1s y tienen los mismos conjuntos de cuatro números cuánticos que los dos electrones del helio. El electrón restante debe ocupar el orbital de menor energía siguiente, el orbital 2s ( o ). Así, la configuración de electrones y el diagrama orbital del litio son:
Un átomo del metal alcalinotérreo berilio, de número atómico 4, contiene cuatro protones en el núcleo y cuatro electrones que lo rodean. El cuarto electrón llena el espacio restante en el orbital 2s.
Un átomo de boro (número atómico 5) contiene cinco electrones. La capa n = 1 se llena con dos electrones y tres electrones ocuparán la capa n = 2. Dado que cualquier subcapa s solo puede contener dos electrones, el quinto electrón debe ocupar el siguiente nivel de energía, que será un orbital 2p. Hay tres orbitales 2p degenerados (m = -1, 0, +1) y el electrón puede ocupar cualquiera de estos orbitales p. Al dibujar los diagramas de orbitales, incluimos cajas vacías para representar cualquier orbital vacío en el mismo subespacio que estamos llenando.
El carbono (número atómico 6) tiene seis electrones. Cuatro de ellos llenan los orbitales 1s y 2s. Los dos electrones restantes ocupan la subcapa 2p. Ahora tenemos la opción de llenar uno de los orbitales 2p y emparejar los electrones o dejar los electrones sin emparejar en dos orbitales p diferentes, pero degenerados. Los orbitales se llenan según la regla de Hund: la configuración de menor energía para un átomo con electrones dentro de un conjunto de orbitales degenerados es la que tiene el máximo número de electrones no emparejados. Así, los dos electrones de los orbitales 2p del carbono tienen idénticos números cuánticos n, l y m y difieren en su número cuántico m (de acuerdo con el principio de exclusión de Pauli). La configuración de electrones y el diagrama de orbitales del carbono son:
El nitrógeno (número atómico 7) llena las subcapas 1s y 2s y tiene un electrón en cada uno de los tres orbitales 2p, de acuerdo con la regla de Hund. Estos tres electrones tienen espines no emparejados. El oxígeno (número atómico 8) tiene un par de electrones en cualquiera de los orbitales 2p (los electrones tienen espines opuestos) y un solo electrón en cada uno de los otros dos. El flúor (número atómico 9) solo tiene un orbital 2p que contiene un electrón no emparejado. Todos los electrones del gas noble neón (número atómico 10) están emparejados y todos los orbitales de las capas n = 1 y n = 2 están llenos. La configuración de electrones y los diagramas orbitales de estos cuatro elementos son:
El metal alcalino sodio (número atómico 11) tiene un electrón más que el átomo de neón. Este electrón debe ir a la subcapa de menor energía disponible, el orbital 3s, dando una configuración 1s22s22p63s1. Los electrones que ocupan los orbitales más externos de la capa (valor más alto de n) se llaman electrones de valencia, y los que ocupan los orbitales de la capa interna se llaman electrones centrales (). Dado que las capas de electrones centrales corresponden a la configuración de electrones de los gases nobles, podemos abreviar la configuración de electrones escribiendo el gas noble que coincide con la configuración de electrones centrales junto con los electrones de valencia en un formato condensado. Para nuestro ejemplo del sodio, el símbolo [Ne] representa los electrones centrales, (1s22s22p6) y nuestra configuración abreviada o condensada es [Ne]3s1.
Del mismo modo, la configuración abreviada del litio puede representarse como [He]2s1, donde [He] representa la configuración del átomo de helio, que es idéntica a la de la capa interna llena del litio. Al escribir las configuraciones de esta manera se destaca la similitud de las configuraciones del litio y del sodio. Ambos átomos, que pertenecen a la familia de los metales alcalinos, tienen un solo electrón en una subcapa de valencia s fuera de un conjunto lleno de capas internas.
El metal alcalinotérreo magnesio (número atómico 12), con sus 12 electrones en una configuración [Ne]3s2, es análogo al miembro de su familia, el berilio, [He]2s2. Ambos átomos tienen una subcapa s llena fuera de sus capas interiores llenas. El aluminio (número atómico 13), con 13 electrones y la configuración de electrones [Ne]3s23p1, es análogo a su pariente, el boro, [He]2s22p1.
La configuración de electrones del silicio (14 electrones), el fósforo (15 electrones), el azufre (16 electrones), el cloro (17 electrones) y el argón (18 electrones) son análogas en cuanto a la configuración de electrones de sus capas exteriores, a las de sus correspondientes miembros de la familia, el carbono, el nitrógeno, el oxígeno, el flúor y el neón, respectivamente, con la salvedad de que el número cuántico principal de la capa exterior de los elementos más pesados se ha incrementado en uno, pasando a ser n = 3. En la se muestra la configuración de electrones de menor energía, o de estado fundamental, de estos elementos, así como la de los átomos de cada uno de los elementos conocidos.
Cuando llegamos al siguiente elemento de la tabla periódica, el metal alcalino potasio (número atómico 19), cabría esperar que empezáramos a añadir electrones al subcapa 3d. Sin embargo, todas las pruebas químicas y físicas disponibles indican que el potasio es como el litio y el sodio, y que el siguiente electrón no se añade al nivel 3d sino que, en cambio, se añade al nivel 4s (). Como se ha comentado anteriormente, el orbital 3d sin nodos radiales tiene mayor energía porque es menos penetrante y está más protegido del núcleo que el 4s, que tiene tres nodos radiales. Así, el potasio tiene una configuración de electrones de [Ar]4s1. Por lo tanto, el potasio se corresponde con el Li y el Na en su configuración de capa de valencia. El siguiente electrón se añade para completar la subcapa 4s y el calcio tiene una configuración de electrones de [Ar]4s2. Esto da al calcio una configuración de electrones de la capa externa correspondiente a la del berilio y el magnesio.
Empezando por el metal de transición escandio (número atómico 21), se añaden sucesivamente electrones adicionales a la subcapa 3d. Este subcapa se llena hasta su capacidad con 10 electrones (recuerde que para l = 2 [orbitales d], hay 2l + 1 = 5 valores de m, lo que significa que hay cinco orbitales d que tienen una capacidad combinada de 10 electrones). La subcapa 4p es la siguiente en llenarse. Observe que para tres series de elementos, desde el escandio (Sc) hasta el cobre (Cu), desde el itrio (Y) hasta la plata (Ag), y desde el lutecio (Lu) hasta el oro (Au), se añaden sucesivamente un total de 10 electrones d a la capa (n - 1) junto a la capa n para llevar esa capa (n - 1) de 8 a 18 electrones. Para dos series, del lantano (La) al lutecio (Lu) y del actinio (Ac) al lawrencio (Lr), se añaden sucesivamente 14 electrones f (l = 3, 2l + 1 = 7 valores m; por lo tanto, siete orbitales con una capacidad combinada de 14 electrones) a la capa (n - 2) para llevar esa capa de 18 electrones a un total de 32 electrones.
La tabla periódica puede ser una poderosa herramienta para predecir la configuración de electrones de un elemento. Sin embargo, encontramos excepciones al orden de llenado de los orbitales que se muestran en la o la . Por ejemplo, la configuración de electrones (mostradas en la ) de los metales de transición cromo (Cr; número atómico 24) y cobre (Cu; número atómico 29), entre otros, no son las que esperaríamos. En general, estas excepciones implican subcapas con energía muy similar, y pequeños efectos pueden conducir a cambios en el orden de llenado.
En el caso del Cr y el Cu, encontramos que las subcapas semillenas y completamente llenas representan aparentemente condiciones de estabilidad preferida. Esta estabilidad es tal que un electrón se desplaza del orbital 4s al 3d para obtener la estabilidad extra de una subcapa 3d semillena (en Cr) o una subcapa 3d llena (en Cu). También se dan otras excepciones. Por ejemplo, se predice que el niobio (Nb, número atómico 41) tiene la configuración de electrones [Kr]5s24d3. Experimentalmente, observamos que su configuración de electrones en estado fundamental es realmente [Kr]5s14d4. Podemos racionalizar esta observación diciendo que las repulsiones electrón-electrón experimentadas al emparejar los electrones en el orbital 5s son mayores que la brecha de energía entre los orbitales 5s y 4d. No existe un método sencillo para predecir las excepciones para los átomos en los que la magnitud de las repulsiones entre los electrones es mayor que las pequeñas diferencias de energía entre las subcapas.
### Configuración de electrones y la tabla periódica
Como se ha descrito anteriormente, la tabla periódica ordena los átomos en función de su número atómico creciente, de modo que los elementos con las mismas propiedades químicas se repiten periódicamente. Cuando se añaden sus configuraciones de electrones a la tabla (), también vemos una recurrencia periódica de configuraciones de electrones similares en las capas exteriores de estos elementos. Como se encuentran en las capas exteriores de un átomo, los electrones de valencia desempeñan el papel más importante en las reacciones químicas. Los electrones exteriores tienen la mayor energía de los electrones de un átomo y se pierden o comparten más fácilmente que los electrones centrales. Los electrones de valencia son también el factor determinante de algunas propiedades físicas de los elementos.
Los elementos de cualquier grupo (o columna) tienen el mismo número de electrones de valencia; los metales alcalinos, litio y sodio, tienen un solo electrón de valencia cada uno, los metales alcalinotérreos, berilio y magnesio, tienen dos cada uno, y los halógenos, flúor y cloro, tienen siete electrones de valencia cada uno. La similitud de las propiedades químicas entre los elementos del mismo grupo se debe a que tienen el mismo número de electrones de valencia. La pérdida, la ganancia o el reparto de electrones de valencia es lo que define la reacción de los elementos.
Es importante recordar que la tabla periódica se elaboró a partir del comportamiento químico de los elementos, mucho antes de que se tuviera una idea de su estructura atómica. Ahora podemos entender por qué la tabla periódica tiene la disposición que tiene: la disposición pone en el mismo grupo los elementos cuyos átomos tienen el mismo número de electrones de valencia. Esta disposición se enfatiza en la , que muestra en forma de tabla periódica la configuración de electrones de la última subcapa que se llena por el principio de Aufbau. Las secciones coloreadas de la muestran las tres categorías de elementos clasificadas por los orbitales que se llenan: grupo principal, transición y elementos de transición interna. Estas clasificaciones determinan qué orbitales se cuentan en la capa de valencia, o en los orbitales del nivel de energía más alto de un átomo.
1. Los elementos del grupo principal (a veces denominados elementos representativos) son aquellos en los que el último electrón añadido entra en un orbital s o p en la capa más externa, mostrados en azul y rojo en la . Esta categoría incluye todos los elementos no metálicos, así como muchos metales y los metaloides. Los electrones de valencia de los elementos del grupo principal son los que tienen el nivel n más alto. Por ejemplo, el galio (Ga, número atómico 31) tiene la configuración de electrones [Ar]43d104, que contiene tres electrones de valencia (subrayados). Los orbitales d completamente llenos cuentan como electrones centrales, no de valencia.
2. Elementos de transición o metales de transición. Son elementos metálicos en los que el último electrón añadido entra en un orbital d. Los electrones de valencia (los que se añaden después de la última configuración de gases nobles) incluyen en estos elementos los electrones ns y (n - 1) d. La definición oficial de la IUPAC de los elementos de transición especifica los que tienen orbitales d parcialmente llenos. Así, los elementos con orbitales completamente llenos (Zn, Cd, Hg, así como Cu, Ag y Au en la ) no son técnicamente elementos de transición. Sin embargo, el término se utiliza con frecuencia para referirse a todo el bloque d (coloreado en amarillo en la ), y adoptaremos este uso en este libro de texto.
3. Los elementos de transición interna son elementos metálicos en los que el último electrón añadido ocupa un orbital f. Se muestran en verde en la . Las capas de valencia de los elementos de transición interna consiste en las subcapas (n - 2)f, (n - 1)d y ns. Hay dos series de transición interna:
El lantano y el actinio, debido a sus similitudes con los demás miembros de la serie, se incluyen y se utilizan para nombrar la serie, aunque sean metales de transición sin electrones f.
### Configuración de electrones de los iones
Los iones se forman cuando los átomos ganan o pierden electrones. Un catión (ion con carga positiva) se forma cuando se eliminan uno o más electrones de un átomo padre. En el caso de los elementos del grupo principal, los electrones que se añadieron en último lugar son los primeros electrones eliminados. Sin embargo, para los metales de transición y los metales de transición interna, los electrones del orbital s son más fáciles de eliminar que los electrones d o f, por lo que se pierden los electrones ns más altos y luego se eliminan los electrones (n - 1)d o (n - 2)f. Un anión (ion con carga negativa) se forma cuando se añaden uno o más electrones a un átomo padre. Los electrones añadidos completan el orden previsto por el principio de Aufbau.
### Conceptos clave y resumen
La energía relativa de las subcapas determina el orden en que se llenan los orbitales atómicos (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, etc.). Las configuración de electrones y los diagramas orbitales pueden determinarse aplicando el principio de exclusión de Pauli (no hay dos electrones que puedan tener el mismo conjunto de cuatro números cuánticos) y la regla de Hund (siempre que sea posible, los electrones conservan los espines no emparejados en orbitales degenerados).
Los electrones de los orbitales más externos, llamados electrones de valencia, son los responsables de la mayor parte del comportamiento químico de los elementos. En la tabla periódica, los elementos con configuraciones de electrones de valencia análogas suelen aparecer dentro del mismo grupo. Hay algunas excepciones al orden de llenado previsto, especialmente cuando se pueden formar orbitales semillenos o completamente llenos. La tabla periódica puede dividirse en tres categorías en función del orbital en el que se coloca el último electrón que se añade: elementos del grupo principal (orbitales s y p), elementos de transición (orbitales d) y elementos de transición interna (orbitales f).
### Ejercicios de química del final del capítulo
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# Estructura electrónica y propiedades periódicas de los elementos
## Variaciones periódicas de las propiedades de los elementos
Los elementos de los grupos (columnas verticales) de la tabla periódica presentan un comportamiento químico similar. Esta similitud se produce porque los miembros de un grupo tienen el mismo número y distribución de electrones en sus capas de valencia. Sin embargo, también existen otros patrones en las propiedades químicas de la tabla periódica. Por ejemplo, a medida que descendemos en un grupo, el carácter metálico de los átomos aumenta. El oxígeno, en la parte superior del grupo 16 (6A), es un gas incoloro; en el centro del grupo, el selenio es un sólido semiconductor; y, hacia el fondo, el polonio es un sólido gris plateado que conduce la electricidad.
A medida que atravesamos un periodo de izquierda a derecha, añadimos un protón al núcleo y un electrón a la capa de valencia con cada elemento sucesivo. A medida que descendemos por los elementos de un grupo, el número de electrones de la capa de valencia permanece constante, pero el número cuántico principal aumenta en uno cada vez. La comprensión de la estructura de los electrones de los elementos nos permite examinar algunas de las propiedades que rigen su comportamiento químico. Estas propiedades varían periódicamente al cambiar la estructura de los electrones de los elementos. Son (1) el tamaño (radio) de los átomos e iones, (2) las energías de ionización y (3) las afinidades de los electrones.
### Variación del radio covalente
La imagen mecánica cuántica hace difícil establecer un tamaño definitivo de un átomo. Sin embargo, hay varias formas prácticas de definir el radio de los átomos y, por tanto, de determinar sus tamaños relativos que dan valores aproximadamente similares. Utilizaremos el radio covalente (), que se define como la mitad de la distancia entre los núcleos de dos átomos idénticos cuando están unidos por un enlace covalente (esta medida es posible porque los átomos dentro de las moléculas siguen conservando gran parte de su identidad atómica). Sabemos que a medida que recorremos un grupo, el número cuántico principal, n, aumenta en uno para cada elemento. Así, los electrones se van añadiendo a una región del espacio cada vez más alejada del núcleo. En consecuencia, el tamaño del átomo (y su radio covalente) debe aumentar a medida que aumentamos la distancia de los electrones más externos al núcleo. Esta tendencia se ilustra para los radios covalentes de los halógenos en la y la . Las tendencias de toda la tabla periódica pueden verse en la .
Como se muestra en la , a medida que nos movemos a través de un periodo de izquierda a derecha, generalmente encontramos que cada elemento tiene un radio covalente más pequeño que el elemento que lo precede. Esto puede parecer contradictorio porque implica que los átomos con más electrones tienen un radio atómico menor. Esto se puede explicar con el concepto de carga nuclear efectiva, o . Es la atracción que ejerce el núcleo sobre un electrón concreto, teniendo en cuenta las posibles repulsiones electrón-electrón. En el caso del hidrógeno, solo hay un electrón, por lo que la carga nuclear (Z) y la carga nuclear efectiva (Zeff) son iguales. Para todos los demás átomos, los electrones internos apantallan parcialmente a los externos de la atracción del núcleo, y por tanto:
El apantallamiento viene determinado por la probabilidad de que otro electrón se encuentre entre el electrón de interés y el núcleo, así como por las repulsiones electrón-electrón que encuentra el electrón de interés. Los electrones centrales son expertos en el apantallamiento, mientras que los electrones de la misma capa de valencia no bloquean la atracción nuclear experimentada por los demás con tanta eficacia. Así, cada vez que pasamos de un elemento a otro a lo largo de un periodo, Z aumenta en uno, pero el apantallamiento solo aumenta ligeramente. Por lo tanto, Zeff aumenta a medida que nos movemos de izquierda a derecha a través de un periodo. La mayor atracción (mayor carga nuclear efectiva) que experimentan los electrones del lado derecho de la tabla periódica los acerca al núcleo, haciendo que los radios covalentes sean más pequeños.
Así, como era de esperar, los electrones más externos o de valencia son los más fáciles de eliminar porque tienen las energías más altas, están más protegidos y están más alejados del núcleo. Por regla general, cuando los elementos representativos forman cationes, lo hacen por la pérdida de los electrones ns o np que se añadieron en último lugar en el proceso de Aufbau. Los elementos de transición, en cambio, pierden los electrones ns antes de empezar a perder los electrones (n - 1)d, aunque los electrones ns se añadan primero, según el principio de Aufbau.
### Variación de los radios iónicos
El radio iónico es la medida utilizada para describir el tamaño de un ion. Un catión siempre tiene menos electrones y el mismo número de protones que el átomo padre; es más pequeño que el átomo del que deriva (). Por ejemplo, el radio covalente de un átomo de aluminio (1s22s22p63s23p1) es de 118 pm, mientras que el radio iónico de un Al3+ (1s22s22p6) es de 68 pm. A medida que se eliminan los electrones de la capa de valencia exterior, los electrones centrales restantes que ocupan las capas más pequeñas experimentan una mayor carga nuclear efectiva Zeff (como se ha comentado) y se acercan aún más al núcleo.
Los cationes con cargas mayores son más pequeños que los cationes con cargas menores (por ejemplo, V2+ tiene un radio iónico de 79 pm, mientras que para los de V3+ es de 64 pm). Bajando por los grupos de la tabla periódica, encontramos que los cationes de elementos sucesivos con la misma carga tienen generalmente radios mayores, lo que corresponde a un aumento del número cuántico principal, n.
Un anión (ion negativo) se forma por la adición de uno o más electrones a la capa de valencia de un átomo. El resultado es una mayor repulsión entre los electrones y una disminución de la Zeff por electrón. Ambos efectos (el aumento del número de electrones y la disminución de la Zeff) hacen que el radio de un anión sea mayor que el del átomo padre (). Por ejemplo, un átomo de azufre ([Ne]3s23p4) tiene un radio covalente de 104 pm, mientras que el radio iónico del anión sulfuro ([Ne]3s23p6) es de 170 pm. Para los elementos consecutivos que descienden en cualquier grupo, los aniones tienen números cuánticos principales más grandes y, por lo tanto, radios más grandes.
Los átomos e iones que tienen la misma configuración de electrones se dicen que son isoelectrónicos. Ejemplos de especies isoelectrónicas son N3–, O2–, F-, Ne, Na+, Mg2+ y Al3+ (1s22s22p6). Otra serie isoelectrónica son P3-, S2-, Cl-, Ar, K+, Ca2+ y Sc3+ ([Ne]3s23p6). Para los átomos o iones que son isoelectrónicos, el número de protones determina el tamaño. Cuanto mayor sea la carga nuclear, menor será el radio en una serie de iones y átomos isoelectrónicos.
### Variación de las energías de ionización
La cantidad de energía necesaria para eliminar el electrón más suelto de un átomo gaseoso en su estado fundamental se llama su primera energía de ionización (IE1). La primera energía de ionización de un elemento, X es la energía necesaria para formar un catión con carga +1:
La energía necesaria para eliminar el segundo electrón más suelto se denomina energía de segunda ionización (IE2).
La energía necesaria para eliminar el tercer electrón es la tercera energía de ionización, y así sucesivamente. Siempre se requiere energía para eliminar los electrones de los átomos o iones, por lo que los procesos de ionización son endotérmicos y los valores del IE son siempre positivos. En el caso de los átomos más grandes, el electrón más suelto se encuentra más lejos del núcleo y, por tanto, es más fácil de eliminar. Por lo tanto, a medida que el tamaño (radio atómico) aumenta, la energía de ionización debería disminuir. Relacionando esta lógica con lo que acabamos de aprender sobre los radios, esperaríamos que las primeras energías de ionización disminuyeran a lo largo de un grupo y aumentaran a lo largo de un periodo.
La grafica la relación entre la primera energía de ionización y el número atómico de varios elementos. Los valores de la primera energía de ionización de los elementos se indican en la . Dentro de un periodo, el IE1 suele aumentar con el aumento de Z. Dentro de un grupo, el valor del IE1 suele disminuir con el aumento de Z. Sin embargo, hay algunas desviaciones sistemáticas de esta tendencia. Observe que la energía de ionización del boro (número atómico 5) es menor que la del berilio (número atómico 4) aunque la carga nuclear del boro es mayor en un protón. Esto se explica porque la energía de las subcapas aumenta a medida que aumenta l, debido a la penetración y al apantallamiento (como se ha comentado anteriormente en este capítulo). Dentro de cualquier capa, los electrones s son más bajos en energía que los electrones p. Esto significa que un electrón s es más difícil de eliminar de un átomo que un electrón p en la misma capa. El electrón eliminado durante la ionización del berilio ([He]2s2) es un electrón s, mientras que el electrón eliminado durante la ionización del boro ([He]2s22p1) es un electrón p; esto resulta en una primera energía de ionización más baja para el boro, aunque su carga nuclear es mayor en un protón. Así, vemos una pequeña desviación de la tendencia prevista que se produce cada vez que se inicia una nueva subcapa.
Otra desviación se produce cuando los orbitales se llenan más de la mitad. La primera energía de ionización para el oxígeno es ligeramente inferior a la del nitrógeno, a pesar de la tendencia al aumento de los valores de IE1 a lo largo de un periodo. Observando el diagrama orbital del oxígeno, podemos ver que la eliminación de un electrón eliminará la repulsión electrón-electrón causada por el emparejamiento de los electrones en el orbital 2p y dará lugar a un orbital medio lleno (que es energéticamente favorable). En los periodos siguientes se producen cambios análogos (note el descenso del azufre después del fósforo en la ).
Eliminar un electrón de un catión es más difícil que eliminar un electrón de un átomo neutro debido a la mayor atracción electrostática hacia el catión. Del mismo modo, eliminar un electrón de un catión con una carga positiva más alta es más difícil que eliminar un electrón de un ion con una carga más baja. Así, las energías de ionización sucesivas para un elemento siempre aumentan. Como se ve en la , hay un gran aumento de las energías de ionización para cada elemento. Este salto corresponde a la eliminación de los electrones centrales, que son más difíciles de eliminar que los de valencia. Por ejemplo, el Sc y el Ga tienen tres electrones de valencia, por lo que el rápido aumento de la energía de ionización se produce después de la tercera ionización.
### Variación de las afinidades de los electrones
La afinidad electrónica (Electron Affinity, EA) es el cambio de energía para el proceso de adición de un electrón a un átomo gaseoso para formar un anión (ion negativo).
Este proceso puede ser endotérmico o exotérmico, dependiendo del elemento. La EA de algunos de los elementos figura en la . Puede ver que muchos de estos elementos tienen valores negativos de EA, lo que significa que se libera energía cuando el átomo gaseoso acepta un electrón. Sin embargo, para algunos elementos, se requiere energía para que el átomo se cargue negativamente y el valor de su EA es positivo. Al igual que en el caso de la energía de ionización, los valores posteriores de EA están asociados a la formación de iones con más carga. La segunda EA es la energía asociada a la adición de un electrón a un anión para formar un ion -2, y así sucesivamente.
Como podríamos predecir, es más fácil añadir un electrón a través de una serie de átomos a medida que la carga nuclear efectiva de los átomos aumenta. A medida que avanzamos de izquierda a derecha a lo largo de un periodo, las EA tienden a ser más negativas. Las excepciones encontradas entre los elementos del grupo 2 (2A), el grupo 15 (5A) y el grupo 18 (8A) pueden entenderse en base a la estructura electrónica de estos grupos. Los gases nobles, del grupo 18 (8A), tienen una capa completamente llena y el electrón entrante debe añadirse a un nivel n superior, lo que es más difícil de hacer. El grupo 2 (2A) tiene una subcapa ns llena, por lo que el siguiente electrón añadido va a la np de mayor energía, por lo que, de nuevo, el valor de la EA observado no es como la tendencia predeciría. Por último, el grupo 15 (5A) tiene una subcapa np semillena y el siguiente electrón debe emparejarse con un electrón np existente. En todos estos casos, la estabilidad relativa inicial de la configuración de electrones altera la tendencia de la EA.
También podríamos esperar que el átomo situado en la parte superior de cada grupo tenga la EA más negativa; sus primeros potenciales de ionización sugieren que estos átomos tienen las mayores cargas nucleares efectivas. Sin embargo, a medida que descendemos en un grupo, vemos que el segundo elemento del grupo es el que más veces tiene una EA negativa. Esto puede atribuirse al pequeño tamaño de la capa n = 2 y a las grandes repulsiones electrón-electrón resultantes. Por ejemplo, el cloro, con un valor EA de -348 kJ/mol, tiene el valor más alto de cualquier elemento de la tabla periódica. La EA del flúor es de -322 kJ/mol. Cuando añadimos un electrón a un átomo de flúor para formar un anión fluoruro (F-), añadimos un electrón a la capa n = 2. El electrón es atraído por el núcleo, pero también hay una repulsión significativa de los otros electrones ya presentes en esta pequeña capa de valencia. El átomo de cloro tiene la misma configuración de electrones en la capa de valencia, pero como el electrón que entra va a la capa n = 3, ocupa una región de espacio considerablemente mayor y las repulsiones electrón-electrón se reducen. El electrón que entra no experimenta tanta repulsión y el átomo de cloro acepta más fácilmente un electrón adicional, lo que resulta en una EA más negativa.
Las propiedades analizadas en esta sección (tamaño de los átomos e iones, carga nuclear efectiva, energías de ionización y afinidades electrónicas) son fundamentales para comprender la reactividad química. Por ejemplo, como el flúor tiene una EA energéticamente favorable y una gran barrera energética a la ionización (IE), es mucho más fácil formar aniones de flúor que cationes. Las propiedades metálicas, como la conductividad y la maleabilidad (la capacidad de formarse en láminas), dependen de que los electrones se puedan eliminar fácilmente. Así, el carácter metálico aumenta a medida que descendemos en un grupo y disminuye a lo largo de un periodo en la misma tendencia observada para el tamaño atómico, porque es más fácil extraer un electrón que está más lejos del núcleo.
### Conceptos clave y resumen
Las configuraciones de electrones nos permiten comprender muchas tendencias periódicas. El radio covalente aumenta a medida que descendemos en un grupo porque el nivel n (tamaño del orbital) aumenta. El radio covalente disminuye en su mayor parte a medida que nos movemos de izquierda a derecha a través de un periodo porque la carga nuclear efectiva experimentada por los electrones aumenta y los electrones son atraídos más estrechamente hacia el núcleo. Los radios aniónicos son mayores que los del átomo padre, mientras que los radios catiónicos son menores, porque el número de electrones de valencia ha cambiado mientras que la carga nuclear ha permanecido constante. La energía de ionización (la energía asociada a la formación de un catión) disminuye a lo largo de un grupo y aumenta sobre todo a lo largo de un periodo, ya que es más fácil retirar un electrón de un orbital más grande y de mayor energía. La afinidad electrónica (la energía asociada a la formación de un anión) es más favorable (exotérmica) cuando los electrones se colocan en orbitales de menor energía, más cerca del núcleo. Por lo tanto, la afinidad electrónica se vuelve cada vez más negativa a medida que nos movemos de izquierda a derecha a través de la tabla periódica y disminuye a medida que descendemos en un grupo. Tanto para los datos de EI como para los de afinidad electrónica, hay excepciones a las tendencias cuando se trata de subcapas completamente llenas o semillenas.
### Ejercicios de química del final del capítulo
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# Enlace químico y geometría molecular
## Introducción
Desde hace tiempo se sabe que el carbono puro se presenta en diferentes formas (alótropos), como el grafito y los diamantes. Pero no fue hasta 1985 cuando se reconoció una nueva forma de carbono: el buckminsterfullereno. Esta molécula debe su nombre al arquitecto e inventor R. Buckminster Fuller (1895–1983), cuyo diseño arquitectónico emblemático era la cúpula geodésica, caracterizada por una estructura de celosía que sostiene una superficie esférica. Las pruebas experimentales revelaron la fórmula, C60, y luego los científicos determinaron cómo 60 átomos de carbono podían formar una molécula simétrica y estable. Se guiaron por la teoría de los enlaces (el tema de este capítulo) que explica cómo los átomos individuales se conectan para formar estructuras más complejas. |
# Enlace químico y geometría molecular
## Enlace iónico
Como ha aprendido, los iones son átomos o moléculas con carga eléctrica. Un catión (un ion positivo) se forma cuando un átomo neutro pierde uno o más electrones de su capa de valencia, y un anión (un ion negativo) se forma cuando un átomo neutro gana uno o más electrones en su capa de valencia.
Los compuestos formados por iones se denominan compuestos iónicos (o sales), y sus iones constituyentes se mantienen unidos por enlaces iónicos: fuerzas electrostáticas de atracción entre cationes y aniones de carga opuesta. Las propiedades de los compuestos iónicos arrojan algo de luz sobre la naturaleza de los enlaces iónicos. Los sólidos iónicos presentan una estructura cristalina y tienden a ser rígidos y quebradizos; también suelen tener puntos de fusión y ebullición elevados, lo que sugiere que los enlaces iónicos son muy fuertes. Los sólidos iónicos también son malos conductores de la electricidad por la misma razón: la fuerza de los enlaces iónicos impide que los iones se muevan libremente en el estado sólido. Sin embargo, la mayoría de los sólidos iónicos se disuelven fácilmente en el agua. Una vez disueltos o fundidos, los compuestos iónicos son excelentes conductores de la electricidad y el calor porque los iones pueden moverse libremente.
Los átomos neutros y sus iones asociados tienen propiedades físicas y químicas muy diferentes. Los átomos de sodio forman el sodio metal, un metal blando de color blanco plateado que arde vigorosamente en el aire y reacciona de forma explosiva con el agua. Los átomos de cloro forman el gas cloro, Cl2, un gas amarillo-verde que es extremadamente corrosivo para la mayoría de los metales y muy venenoso para los animales y las plantas. La vigorosa reacción entre los elementos sodio y cloro forma el compuesto blanco y cristalino, cloruro de sodio, la sal de mesa común, que contiene cationes de sodio y aniones de cloruro (). El compuesto formado por estos iones presenta propiedades totalmente diferentes a las de los elementos sodio y cloro. El cloro es venenoso, pero el cloruro de sodio es esencial para la vida; los átomos de sodio reaccionan vigorosamente con el agua, pero el cloruro de sodio simplemente se disuelve en el agua.
### Formación de compuestos iónicos
Los compuestos iónicos binarios están compuestos por solo dos elementos: un metal (que forma los cationes) y un no metal (que forma los aniones). Por ejemplo, el NaCl es un compuesto iónico binario. Podemos pensar en la formación de tales compuestos en términos de las propiedades periódicas de los elementos. Muchos elementos metálicos tienen potenciales de ionización relativamente bajos y pierden electrones con facilidad. Estos elementos se sitúan a la izquierda en un periodo o cerca de la parte inferior de un grupo en la tabla periódica. Los átomos no metálicos tienen afinidades electrónicas relativamente altas y, por lo tanto, ganan fácilmente los electrones perdidos por los átomos metálicos, llenando así sus capas de valencia. Los elementos no metálicos se encuentran en la esquina superior derecha de la tabla periódica.
Como todas las sustancias deben ser eléctricamente neutras, el número total de cargas positivas de los cationes de un compuesto iónico debe ser igual al número total de cargas negativas de sus aniones. La fórmula de un compuesto iónico representa el cociente más sencillo entre el número de iones necesarios para dar un número idéntico de cargas positivas y negativas. Por ejemplo, la fórmula del óxido de aluminio, Al2O3, indica que este compuesto iónico contiene dos cationes de aluminio, Al3+, por cada tres aniones de óxido, O2− [así, (2 +3) + (3 –2) = 0].
Sin embargo, es importante señalar que la fórmula de un compuesto iónico no representa la disposición física de sus iones. Es incorrecto referirse a una "molécula" de cloruro de sodio (NaCl) porque no hay un solo enlace iónico, per se, entre ningún par específico de iones de sodio y cloruro. Las fuerzas de atracción entre los iones son isotrópicas, es decir, son iguales en todas las direcciones, lo que significa que cualquier ion particular es atraído por igual por todos los iones cercanos de carga opuesta. Esto hace que los iones se organicen en una estructura de red tridimensional fuertemente unida. El cloruro de sodio, por ejemplo, está formado por una disposición regular de igual número de cationes Na+ y aniones Cl– ().
La fuerte atracción electrostática entre los iones Na+ y Cl– los mantiene fuertemente unidos en el NaCl sólido. Se necesitan 769 kJ de energía para disociar un mol de NaCl sólido en iones gaseosos separados de Na+ y Cl–:
### Estructuras electrónicas de los cationes
Al formar un catión, un átomo de un elemento del grupo principal tiende a perder todos sus electrones de valencia, asumiendo así la estructura electrónica del gas noble que le precede en la tabla periódica. En los grupos 1 (los metales alcalinos) y 2 (los metales alcalinotérreos), los números de grupo son iguales a los números de electrones de la capa de valencia y, en consecuencia, a las cargas de los cationes formados a partir de átomos de estos elementos cuando se eliminan todos los electrones de la capa de valencia. Por ejemplo, el calcio es un elemento del grupo 2 cuyos átomos neutros tienen 20 electrones y una configuración de electrones en estado fundamental de 1s22s22p63s23p64s2. Cuando un átomo de Ca pierde sus dos electrones de valencia, el resultado es un catión con 18 electrones, una carga 2+ y una configuración electrónica de 1s22s22p63s23p6. Por lo tanto, el ion Ca2+ es isoelectrónico con el gas noble Ar.
Para los grupos 13–17, los números de grupo superan en 10 el número de electrones de valencia (teniendo en cuenta la posibilidad de subcapas d completas en los átomos de los elementos del cuarto periodo y superiores). Así, la carga de un catión formado por la pérdida de todos los electrones de valencia es igual al número de grupo menos 10. Por ejemplo, el aluminio (en el grupo 13) forma iones 3+ (Al3+).
Las excepciones al comportamiento esperado afectan a los elementos situados en la parte inferior de los grupos. Además de los iones esperados Tl3+, Sn4+, Pb4+, y Bi5+, una pérdida parcial de los electrones de la capa de valencia de estos átomos también puede conducir a la formación de iones Tl+, Sn2+, Pb2+, y Bi3+. La formación de estos cationes 1+, 2+ y 3+, se atribuye al efecto de par inerte, que refleja la energía relativamente baja del par de electrones de valencia s en los átomos de los elementos pesados de los grupos 13, 14 y 15. El mercurio (grupo 12) también presenta un comportamiento inesperado: forma un ion diatómico, (un ion formado por dos átomos de mercurio, con un enlace Hg-Hg), además del esperado ion monatómico Hg2+ (formado por un solo átomo de mercurio).
Los elementos metálicos de transición y de transición interna se comportan de manera diferente a los elementos del grupo principal. La mayoría de los cationes de los metales de transición tienen cargas 2+ o 3+ que resultan de la pérdida de sus electrones s más externos en primer lugar, a veces seguido de la pérdida de uno o dos electrones d de la capa más próxima. Por ejemplo, el hierro (1s22s22p63s23p63d64s2) forma el ion Fe2+ (1s22s22p63s23p63d6) por la pérdida de los electrones 4s y el ion Fe3+ (1s22s22p63s23p63d5) por la pérdida de los electrones 4s y uno de los 3d. Aunque los orbitales d de los elementos de transición son (según el principio de Aufbau) los últimos en llenarse al construir la configuración de electrones, los electrones s más externos son los primeros en perderse cuando estos átomos se ionizan. Cuando los metales de transición interna forman iones, suelen tener una carga 3+, resultado de la pérdida de sus electrones s más externos y de un electrón d o f.
### Estructuras de electrones de los aniones
La mayoría de los aniones monatómicos se forman cuando un átomo neutro no metálico gana suficientes electrones para llenar completamente sus orbitales exteriores s y p, alcanzando así la configuración de electrones del siguiente gas noble. Por lo tanto, es sencillo determinar la carga de dicho ion negativo: La carga es igual al número de electrones que hay que ganar para llenar los orbitales s y p del átomo padre. El oxígeno, por ejemplo, tiene la configuración electrónica 1s22s22p4, mientras que el anión oxígeno tiene la configuración electrónica del gas noble neón (Ne), 1s22s22p6. Los dos electrones adicionales necesarios para llenar los orbitales de valencia dan al ion óxido la carga de 2– (O2–).
### Conceptos clave y resumen
Los átomos ganan o pierden electrones para formar iones con configuraciones de electrones especialmente estables. Las cargas de los cationes formados por los metales representativos pueden determinarse fácilmente porque, con pocas excepciones, las estructuras de electrones de estos iones tienen una configuración de gas noble o una capa de electrones completamente llena. Las cargas de los aniones formados por los no metales también pueden determinarse fácilmente porque estos iones se forman cuando los átomos no metálicos ganan suficientes electrones para llenar sus capas de valencia.
### Ejercicios de fin de capítulo de Química
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# Enlace químico y geometría molecular
## Enlace covalente
El enlace iónico es el resultado de la atracción electrostática de los iones con carga opuesta que se produce normalmente por la transferencia de electrones entre átomos metálicos y no metálicos. Un tipo diferente de enlace resulta de la atracción mutua de los átomos por un par de electrones "compartidos". Estos enlaces se denominan enlaces covalentes. Los enlaces covalentes se forman entre dos átomos cuando ambos tienen tendencias similares a atraer electrones hacia sí (es decir, cuando ambos átomos tienen energías de ionización y afinidades electrónicas idénticas o bastante similares). Por ejemplo, dos átomos de hidrógeno se unen covalentemente para formar una molécula de H2; cada átomo de hidrógeno en la molécula de H2 tiene dos electrones que lo estabilizan, lo que da a cada átomo el mismo número de electrones de valencia que el gas noble He.
Los compuestos que contienen enlaces covalentes presentan propiedades físicas diferentes a las de los compuestos iónicos. Como la atracción entre las moléculas, que son eléctricamente neutras, es más débil que la que existe entre los iones cargados eléctricamente, los compuestos covalentes suelen tener puntos de fusión y ebullición mucho más bajos que los iónicos. De hecho, muchos compuestos covalentes son líquidos o gases a temperatura ambiente y, en su estado sólido, suelen ser mucho más blandos que los sólidos iónicos. Además, mientras que los compuestos iónicos son buenos conductores de la electricidad cuando se disuelven en agua, la mayoría de los compuestos covalentes son insolubles en agua; como son eléctricamente neutros, son malos conductores de la electricidad en cualquier estado.
### Formación de enlaces covalentes
Los átomos no metálicos suelen formar enlaces covalentes con otros átomos no metálicos. Por ejemplo, la molécula de hidrógeno, H2, contiene un enlace covalente entre sus dos átomos de hidrógeno. La ilustra por qué se forma este enlace. Empezando por el extremo derecho, tenemos dos átomos de hidrógeno separados con una energía potencial particular, indicada por la línea roja. A lo largo del eje x está la distancia entre los dos átomos. A medida que los dos átomos se acercan (moviéndose hacia la izquierda a lo largo del eje x), sus orbitales de valencia (1s) comienzan a superponerse. Los electrones individuales de cada átomo de hidrógeno interactúan entonces con ambos núcleos atómicos, ocupando el espacio que rodea a ambos átomos. La fuerte atracción de cada electrón compartido a ambos núcleos estabiliza el sistema, y la energía potencial disminuye a medida que la longitud de enlace disminuye. Si los átomos siguen acercándose, las cargas positivas de los dos núcleos comienzan a repelerse y la energía potencial aumenta. La longitud de enlace se determina por la distancia a la que se alcanza la menor energía potencial.
Es esencial recordar que hay que añadir energía para romper los enlaces químicos (un proceso endotérmico), mientras que la formación de enlaces químicos libera energía (un proceso exotérmico). En el caso del H2, el enlace covalente es muy fuerte; hay que añadir una gran cantidad de energía, 436 kJ, para romper los enlaces en un mol de moléculas de hidrógeno y hacer que los átomos se separen:
De manera inversa, se libera la misma cantidad de energía cuando se forma un mol de moléculas de H2 a partir de dos moles de átomos de H:
### Enlaces covalentes puros y polares
Si los átomos que forman un enlace covalente son idénticos, como en el H2, el Cl2 y otras moléculas diatómicas, entonces los electrones del enlace deben compartirse por igual. Lo denominamos enlace covalente puro. Los electrones compartidos en los enlaces covalentes puros tienen la misma probabilidad de estar cerca de cada núcleo.
En el caso del Cl2, cada átomo comienza con siete electrones de valencia y cada Cl comparte un electrón con el otro, formando un enlace covalente:
El número total de electrones alrededor de cada átomo consta de seis electrones no enlazantes y dos compartidos (es decir, enlazantes) para un total de ocho electrones, lo que coincide con el número de electrones de valencia del gas noble argón. Como los átomos de enlace son idénticos, el Cl2 también presenta un enlace covalente puro.
Cuando los átomos unidos por un enlace covalente son diferentes, los electrones de enlace se comparten, pero ya no de forma equitativa. En cambio, los electrones de enlace son más atraídos por un átomo que por el otro, dando lugar a un desplazamiento de la configuración electrónica hacia ese átomo. Esta distribución desigual de electrones se conoce como enlace covalente polar, caracterizado por una carga positiva parcial en un átomo y una carga negativa parcial en el otro. El átomo que atrae los electrones con más fuerza adquiere la carga parcial negativa y viceversa. Por ejemplo, los electrones del enlace H-Cl de una molécula de cloruro de hidrógeno pasan más tiempo cerca del átomo de cloro que del de hidrógeno. Así, en una molécula de HCl, el átomo de cloro tiene una carga parcial negativa y el átomo de hidrógeno tiene una carga parcial positiva. La muestra la distribución de electrones en el enlace H-Cl. Observe que el área sombreada alrededor del de Cl es mucho más grande que alrededor del de H. Compare con la , que muestra la distribución uniforme de electrones en el enlace no polar del H2.
A veces designamos los átomos positivos y negativos de un enlace covalente polar utilizando una letra griega minúscula "delta", δ, con un signo más o un signo menos para indicar si el átomo tiene una carga positiva parcial (δ+) o una carga negativa parcial (δ-). Esta simbología se muestra para la molécula H-Cl en la .
### Electronegatividad
El hecho de que un enlace sea covalente no polar o polar viene determinado por una propiedad de los átomos enlazados llamada electronegatividad. La electronegatividad es una medida de la tendencia de un átomo a atraer electrones (o configuración electrónica) hacia sí mismo. Determina cómo se distribuyen los electrones compartidos entre los dos átomos de un enlace. Cuanto más fuertemente atraiga un átomo los electrones de sus enlaces, mayor será su electronegatividad. Los electrones de un enlace covalente polar se desplazan hacia el átomo más electronegativo; así, el átomo más electronegativo es el que tiene la carga negativa parcial. Cuanto mayor sea la diferencia de electronegatividad, más polarizada estará la distribución de electrones y mayores serán las cargas parciales de los átomos.
La muestra los valores de electronegatividad de los elementos según la propuesta de uno de los químicos más famosos del siglo XX: Linus Pauling (). En general, la electronegatividad aumenta de izquierda a derecha a través de un periodo en la tabla periódica y disminuye hacia abajo en un grupo. Así, los no metales, que se encuentran en la parte superior derecha, tienden a tener las mayores electronegatividades, siendo el flúor el elemento más electronegativo de todos (EN = 4,0). Los metales tienden a ser elementos menos electronegativos, y los metales del grupo 1 tienen las electronegatividades más bajas. Note que los gases nobles están excluidos de esta figura porque estos átomos no suelen compartir electrones con otros átomos ya que tienen una capa de valencia completa. (Aunque existen compuestos de gases nobles como el XeO2, solo pueden formarse en condiciones extremas, por lo que no encajan perfectamente en el modelo general de electronegatividad).
### Electronegatividad frente a la afinidad electrónica
Debemos tener cuidado de no confundir la electronegatividad y la afinidad electrónica. La afinidad electrónica de un elemento es una cantidad física medible, es decir, la energía liberada o absorbida cuando un átomo aislado en fase gaseosa adquiere un electrón, medida en kJ/mol. La electronegatividad, por su parte, describe la fuerza con la que un átomo atrae los electrones en un enlace. Es una cantidad adimensional que se calcula, no se mide. Pauling obtuvo los primeros valores de electronegatividad comparando las cantidades de energía necesarias para romper diferentes tipos de enlaces. Eligió una escala relativa arbitraria que va de 0 a 4.
### Electronegatividad y tipo de enlace
El valor absoluto de la diferencia de electronegatividad (ΔEN) de dos átomos enlazados proporciona una medida aproximada de la polaridad que cabe esperar en el enlace y, por tanto, del tipo de enlace. Cuando la diferencia es muy pequeña o nula, el enlace es covalente y no polar. Cuando es grande, el enlace es polar covalente o iónico. Los valores absolutos de las diferencias de electronegatividad entre los átomos de los enlaces H-H, H-Cl y Na-Cl son 0 (no polar), 0,9 (polar covalente) y 2,1 (iónico), respectivamente. El grado en que los electrones se comparten entre los átomos varía desde completamente igual (enlace covalente puro) hasta nada (enlace iónico). La muestra la relación entre la diferencia de electronegatividad y el tipo de enlace.
Una aproximación a las diferencias de electronegatividad asociadas a los enlaces covalentes, covalentes polares e iónicos se muestra en la . Sin embargo, esta tabla es solo una guía general, con muchas excepciones. Por ejemplo, los átomos de H y F en el HF tienen una diferencia de electronegatividad de 1,9, y los átomos de N y H en el NH3 una diferencia de 0,9, y sin embargo ambos compuestos forman enlaces que se consideran covalentes polares. Así mismo, los átomos de Na y Cl en el NaCl tienen una diferencia de electronegatividad de 2,1, y los átomos de Mn e I en el MnI2 tienen una diferencia de 1,0, y sin embargo ambas sustancias forman compuestos iónicos.
La mejor guía para determinar el carácter covalente o iónico de un enlace es considerar los tipos de átomos implicados y sus posiciones relativas en la tabla periódica. Los enlaces entre dos no metales suelen ser covalentes; los enlaces entre un metal y un no metal suelen ser iónicos.
Algunos compuestos contienen tanto enlaces covalentes como iónicos. Los átomos de los iones poliatómicos, como el OH-, y se mantienen unidos por enlaces covalentes polares. Sin embargo, estos iones poliatómicos forman compuestos iónicos al combinarse con iones de carga opuesta. Por ejemplo, el nitrato de potasio, KNO3, contiene el catión K+ y el anión poliatómico . Por lo tanto, el enlace en el nitrato de potasio es iónico, resultado de la atracción electrostática entre los iones K+ y así como covalente entre los átomos de nitrógeno y oxígeno en
### Conceptos clave y resumen
Los enlaces covalentes se forman cuando los electrones se comparten entre átomos y son atraídos por los núcleos de ambos átomos. En los enlaces covalentes puros, los electrones se reparten por igual. En los enlaces covalentes polares, los electrones se reparten de forma desigual, ya que un átomo ejerce una fuerza de atracción sobre los electrones más fuerte que el otro. La capacidad de un átomo para atraer un par de electrones en un enlace químico se denomina electronegatividad. La diferencia de electronegatividad entre dos átomos determina lo polar que será un enlace. En una molécula diatómica con dos átomos idénticos, no hay diferencia de electronegatividad, por lo que el enlace es no polar o covalente puro. Cuando la diferencia de electronegatividad es muy grande, como ocurre entre metales y no metales, el enlace se caracteriza como iónico.
### Ejercicios de química del final del capítulo
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# Enlace químico y geometría molecular
## Símbolos y estructuras de Lewis
Hasta ahora, en este capítulo, hemos hablado de los distintos tipos de enlaces que se forman entre átomos o iones. En todos los casos, estos enlaces implican el intercambio o la transferencia de electrones de la capa de valencia entre los átomos. En esta sección, exploraremos el método típico para representar los electrones de la capa de valencia y los enlaces químicos, es decir, los símbolos de Lewis y las estructuras de Lewis.
### Símbolos de Lewis
Utilizamos los símbolos de Lewis para describir las configuraciones de los electrones de valencia de los átomos e iones monoatómicos. Un símbolo de Lewis consiste en un símbolo elemental rodeado de un punto por cada uno de sus electrones de valencia:
La muestra los símbolos de Lewis para los elementos del tercer periodo de la tabla periódica.
Los símbolos de Lewis también pueden utilizarse para ilustrar la formación de cationes a partir de átomos, como se muestra aquí para el sodio y el calcio:
Asimismo, pueden utilizarse para mostrar la formación de aniones a partir de átomos, como se muestra aquí para el cloro y el azufre:
La demuestra el uso de los símbolos de Lewis para mostrar la transferencia de electrones durante la formación de compuestos iónicos.
### Estructuras de Lewis
También utilizamos los símbolos de Lewis para indicar la formación de enlaces covalentes, que se muestran en las estructuras de Lewis, dibujos que describen el enlace en moléculas e iones poliatómicos. Por ejemplo, cuando dos átomos de cloro forman una molécula de cloro, comparten un par de electrones:
La estructura de Lewis indica que cada átomo de Cl tiene tres pares de electrones que no se utilizan en el enlace (llamados pares solitarios) y un par de electrones compartido (escrito entre los átomos). A veces se utiliza un guion (o línea) para indicar un par de electrones compartido:
Un único par de electrones compartido se denomina enlace simple. Cada átomo de Cl interactúa con ocho electrones de valencia: los seis de los pares solitarios y los dos del enlace simple.
### La regla del octeto
Las otras moléculas de halógeno (F2, Br2, I2, y At2) forman enlaces como los de la molécula de cloro: un enlace simple entre átomos y tres pares solitarios de electrones por átomo. Esto permite que cada átomo de halógeno tenga una configuración electrónica de gas noble. La tendencia de los átomos del grupo principal a formar suficientes enlaces para obtener ocho electrones de valencia se conoce como la regla del octeto.
El número de enlaces que puede formar un átomo puede predecirse a menudo a partir del número de electrones necesarios para alcanzar un octeto (ocho electrones de valencia); esto es especialmente cierto en el caso de los no metales del segundo periodo de la tabla periódica (C, N, O y F). Por ejemplo, cada átomo de un elemento del grupo 14 tiene cuatro electrones en su capa más externa y, por tanto, necesita cuatro electrones más para alcanzar un octeto. Estos cuatro electrones se obtienen al formar cuatro enlaces covalentes, como se ilustra aquí con el carbono en CCl4 (tetracloruro de carbono) y el silicio en SiH4 (silano). Como el hidrógeno solo necesita dos electrones para llenar su capa de valencia, es una excepción a la regla del octeto. Los elementos de transición y los elementos de transición internos tampoco siguen la regla del octeto:
Los elementos del grupo 15, como el nitrógeno, tienen cinco electrones de valencia en el símbolo atómico de Lewis: un par solitario y tres electrones no apareados. Para obtener un octeto, estos átomos forman tres enlaces covalentes, como en el NH3 (amoníaco). El oxígeno y otros átomos del grupo 16 obtienen un octeto formando dos enlaces covalentes:
### Enlaces dobles y triples
Como se mencionó anteriormente, cuando un par de átomos comparte un par de electrones, lo llamamos enlace simple. Sin embargo, un par de átomos puede necesitar compartir más de un par de electrones para conseguir el octeto necesario. Un doble enlace se forma cuando se comparten dos pares de electrones entre un par de átomos, como ocurre entre los átomos de carbono y oxígeno del CH2O (formaldehído) y entre los dos átomos de carbono del C2H4 (etileno):
Un triple enlace se forma cuando un par de átomos comparten tres pares de electrones, como en el monóxido de carbono (CO) y el ion cianuro (CN–):
### Escribir estructuras de Lewis con la regla del octeto
En moléculas e iones moleculares muy simples, podemos escribir las estructuras de Lewis simplemente emparejando los electrones no pareados de los átomos que las componen. Vea estos ejemplos:
En moléculas e iones moleculares más complicados, es útil seguir el procedimiento paso a paso que se describe aquí:
1. Determine el número total de electrones de valencia (capa externa). Para los cationes, reste un electrón por cada carga positiva. Para los aniones, añada un electrón por cada carga negativa.
2. Dibuje una estructura de esqueleto de la molécula o del ion, disponiendo los átomos alrededor de un átomo central. (Por lo general, el elemento menos electronegativo se colocar en el centro). Conecte cada átomo al átomo central con un enlace simple (un par de electrones).
3. Distribuya los electrones restantes como pares solitarios en los átomos terminales (excepto el hidrógeno), completando un octeto alrededor de cada átomo.
4. Coloque todos los electrones restantes en el átomo central.
5. Reordene los electrones de los átomos exteriores para hacer enlaces múltiples con el átomo central a fin de obtener octetos cuando sea posible.
Determinemos las estructuras de Lewis del SiH4, NO+, y OF2 como ejemplos al seguir este procedimiento:
1. Determine el número total de electrones de valencia (capa externa) en la molécula o el ion
2. Dibuje una estructura de esqueleto de la molécula o del ion, disponiendo los átomos alrededor de un átomo central y conectando cada átomo al átomo central con un enlace simple (un par de electrones). (Note que denotamos los iones con corchetes alrededor de la estructura, indicando la carga fuera de los corchetes:)
Cuando son posibles varias disposiciones de los átomos, como en el caso de debemos utilizar las pruebas experimentales para elegir la correcta. En general, los elementos menos electronegativos tienen más probabilidades de ser átomos centrales. En el átomo de carbono menos electronegativo ocupa la posición central y lo rodean los átomos de oxígeno e hidrógeno. Otros ejemplos son el P en POCl3, el S en SO2 y el Cl en Una excepción es que el hidrógeno casi nunca es un átomo central. Al ser el elemento más electronegativo, el flúor tampoco puede ser un átomo central.
3. Distribuya los electrones restantes como pares solitarios en los átomos terminales (excepto el hidrógeno) para completar sus capas de valencia con un octeto de electrones.
4. Coloque todos los electrones restantes en el átomo central.
5. Reordene los electrones de los átomos exteriores para hacer enlaces múltiples con el átomo central a fin de obtener octetos siempre que sea posible.
### Excepciones a la regla del octeto
Muchas moléculas covalentes tienen átomos centrales que no tienen ocho electrones en sus estructuras de Lewis. Estas moléculas se dividen en tres categorías:
1. Las moléculas de electrones impares tienen un número impar de electrones de valencia y, por tanto, un electrón no pareado.
2. Las moléculas deficientes en electrones tienen un átomo central que tiene menos electrones de los necesarios para una configuración de gas noble.
3. Las moléculas hipervalentes tienen un átomo central que tiene más electrones de los necesarios para una configuración de gas noble.
### Moléculas de electrones impares
Llamamos radicales libres a las moléculas que contienen un número impar de electrones. El óxido nítrico, NO, es un ejemplo de molécula de electrones impares; se produce en los motores de combustión interna cuando el oxígeno y el nitrógeno reaccionan a altas temperaturas.
Para dibujar la estructura de Lewis de una molécula de electrones impares como el NO, seguimos los mismos cinco pasos que para otras moléculas, pero con algunos cambios menores:
1. Determine el número total de electrones de valencia (capa externa). La suma de los electrones de valencia es 5 (de N) + 6 (de O) = 11. El número impar nos indica inmediatamente que tenemos un radical libre, por lo que sabemos que no todos los átomos pueden tener ocho electrones en su capa de valencia.
2. Dibuje una estructura de esqueleto de la molécula. Podemos dibujar fácilmente un esqueleto con un enlace simple N-O: N-O
3. Distribuir los electrones restantes como pares solitarios en los átomos terminales. En este caso, no hay un átomo central, por lo que distribuimos los electrones alrededor de ambos átomos. En estas situaciones le damos ocho electrones al átomo más electronegativo, por lo que el oxígeno tiene la capa de valencia llena:
4. Colocar todos los electrones restantes en el átomo central. Como no hay electrones restantes, este paso no se aplica.
5. Reordenar los electrones para hacer enlaces múltiples con el átomo central para obtener octetos siempre que sea posible. Sabemos que una molécula de electrones impares no puede tener un octeto por cada átomo, pero queremos que cada átomo se acerque lo más posible a un octeto. En este caso, el nitrógeno solo tiene cinco electrones a su alrededor. Para acercarnos a un octeto para el nitrógeno, tomamos uno de los pares solitarios del oxígeno y lo utilizamos para formar un doble enlace NO. (No podemos tomar otro par solitario de electrones en el oxígeno y formar un triple enlace porque el nitrógeno tendría entonces nueve electrones:)
### Moléculas deficientes en electrones
También encontraremos algunas moléculas que contienen átomos centrales que no tienen una capa de valencia llena. Por lo general, se trata de moléculas con átomos centrales de los grupos 2 y 13, átomos exteriores que son hidrógeno u otros átomos que no forman enlaces múltiples. Por ejemplo, en las estructuras de Lewis del dihidruro de berilio, BeH2, y del trifluoruro de boro, BF3, los átomos de berilio y de boro solo tienen cuatro y seis electrones respectivamente. Es posible dibujar una estructura con un doble enlace entre un átomo de boro y un átomo de flúor en el BF3, satisfaciendo la regla del octeto, pero las pruebas experimentales indican que las longitudes de los enlaces se acercan más a las esperadas para los enlaces simples B-F. Esto sugiere que la mejor estructura de Lewis tiene tres enlaces simples B-F y un boro deficiente en electrones. La reactividad del compuesto también es consistente con un boro deficiente en electrones. Sin embargo, los enlaces B-F son ligeramente más cortos de lo que se espera en realidad para los enlaces simples B-F, lo que indica que se encuentra algún carácter de doble enlace en la molécula real.
Un átomo como el de boro en el BF3, que no tiene ocho electrones, es muy reactivo. Se combina fácilmente con una molécula que contenga un átomo con un par solitario de electrones. Por ejemplo, el NH3 reacciona con el BF3 porque el par solitario del nitrógeno puede compartirse con el átomo de boro:
### Moléculas hipervalentes
Los elementos del segundo periodo de la tabla periódica (n = 2) solo pueden albergar ocho electrones en sus orbitales de la capa de valencia porque solo tienen cuatro orbitales de valencia (un orbital 2s y tres 2p). Los elementos de los periodos tercero y superior (n ≥ 3) tienen más de cuatro orbitales de valencia y pueden compartir más de cuatro pares de electrones con otros átomos porque tienen orbitales d vacíos en la misma capa. Las moléculas formadas a partir de estos elementos se denominan a veces moléculas hipervalentes. muestra las estructuras de Lewis de dos moléculas hipervalentes, PCl5 y SF6.
En algunas moléculas hipervalentes, como el IF5 y el XeF4, algunos de los electrones de la capa exterior del átomo central son pares solitarios:
Cuando escribimos las estructuras de Lewis de estas moléculas, encontramos que nos sobran electrones después de llenar las capas de valencia de los átomos exteriores con ocho electrones. Estos electrones adicionales deben asignarse al átomo central.
### Conceptos clave y resumen
Las estructuras electrónicas de valencia pueden visualizarse dibujando símbolos de Lewis (para átomos e iones monoatómicos) y estructuras de Lewis (para moléculas e iones poliatómicos). Los pares solitarios, los electrones no apareados y los enlaces simples, dobles o triples se utilizan para indicar dónde se encuentran los electrones de valencia alrededor de cada átomo en una estructura de Lewis. La mayoría de las estructuras -especialmente las que contienen elementos de segunda fila- obedecen a la regla del octeto, en la que cada átomo (excepto el H) está rodeado por ocho electrones. Las excepciones a la regla del octeto se presentan en las moléculas de electrones impares (radicales libres), en las moléculas deficientes en electrones y en las moléculas hipervalentes.
### Ejercicios de química del final del capítulo
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# Enlace químico y geometría molecular
## Cargas formales y resonancia
En la sección anterior, discutimos cómo escribir estructuras de Lewis para moléculas e iones poliatómicos. Sin embargo, como hemos visto, en algunos casos parece haber más de una estructura válida para una molécula. Podemos utilizar el concepto de cargas formales para predecir la estructura de Lewis más apropiada cuando más de una es razonable.
### Cálculo de la carga formal
La carga formal de un átomo en una molécula es la carga hipotética que tendría el átomo si pudiéramos redistribuir los electrones de los enlaces de manera uniforme entre los átomos. Otra forma de decir esto es que la carga formal es el resultado de tomar el número de electrones de valencia de un átomo neutro, restar los electrones no enlazantes y luego restar el número de enlaces conectados a ese átomo en la estructura de Lewis.
Así, calculamos la carga formal de la siguiente manera:
Podemos volver a comprobar los cálculos de las cargas formales determinando la suma de las cargas formales de toda la estructura. La suma de las cargas formales de todos los átomos de una molécula debe ser cero; la suma de las cargas formales de un ion debe ser igual a la carga del ion.
Debemos recordar que la carga formal calculada en un átomo no es la carga real del átomo en la molécula. La carga formal es solo un procedimiento para contabilizar; no indica la presencia de cargas reales.
### Uso de la carga formal para predecir la estructura molecular
La disposición de los átomos en una molécula o ion se denomina estructura molecular. En muchos casos, seguir los pasos para escribir las estructuras de Lewis puede conducir a más de una estructura molecular posible -diferentes colocaciones de enlaces múltiples y de electrones de un solo par o diferentes disposiciones de los átomos, por ejemplo. Unas cuantas pautas relacionadas con la carga formal pueden ser útiles para decidir cuál de las posibles estructuras es la más probable para una molécula o un ion en particular:
1. Una estructura molecular en la que todas las cargas formales son cero es preferible a otra en la que algunas cargas formales son diferentes a cero.
2. Si la estructura de Lewis debe tener cargas formales diferentes a cero, es preferible la disposición con las menores cargas formales diferentes a cero.
3. Las estructuras de Lewis son preferibles cuando las cargas formales adyacentes son cero o de signo contrario.
4. Cuando debemos elegir entre varias estructuras de Lewis con distribuciones similares de cargas formales, es preferible la estructura con las cargas formales negativas en los átomos más electronegativos.
Para ver cómo se aplican estas directrices, consideremos algunas estructuras posibles en el dióxido de carbono,CO2. Por nuestro análisis anterior sabemos que el átomo menos electronegativo suele ocupar la posición central, pero las cargas formales nos permiten entender por qué ocurre esto. Podemos dibujar tres posibilidades para la estructura: carbono en el centro y dobles enlaces, carbono en el centro con un enlace simple y triple, y oxígeno en el centro con dobles enlaces:
Comparando las tres cargas formales, podemos identificar definitivamente la estructura de la izquierda como preferible porque solo tiene cargas formales de cero (directriz 1).
Otro ejemplo es el ion tiocianato, un ion formado por un átomo de carbono, un átomo de nitrógeno y un átomo de azufre, que puede tener tres estructuras moleculares diferentes: NCS–, CNS–, o CSN–. Las cargas formales presentes en cada una de estas estructuras moleculares pueden ayudarnos a elegir la disposición más probable de los átomos. Aquí se muestran las posibles estructuras de Lewis y las cargas formales en cada una de las tres posibles estructuras del ion tiocianato:
Note que la suma de las cargas formales en cada caso es igual a la carga del ion (–1). Sin embargo, es preferible la primera disposición de los átomos porque tiene el menor número de átomos con cargas formales no nulas (directriz 2). Además, esta disposición coloca el átomo menos electronegativo en el centro, y la carga negativa en el elemento más electronegativo (directriz 4).
### Resonancia
Observe que la estructura más probable para el anión nitrito en el puede dibujarse en realidad de dos formas diferentes, que se distinguen por la ubicación de los enlaces N-O y N=O:
Si los iones de nitrito contienen efectivamente un enlace simple y uno doble, cabría esperar que las dos longitudes de enlace fueran diferentes. Un doble enlace entre dos átomos es más corto (y más fuerte) que un enlace simple entre los mismos dos átomos. Los experimentos muestran, sin embargo, que los dos enlaces N-O en tienen la misma resistencia y longitud, y son idénticos en todas las demás propiedades.
No es posible escribir una única estructura de Lewis para en el que el nitrógeno tiene un octeto y ambos enlaces son equivalentes. En su lugar, utilizamos el concepto de resonancia: si se pueden escribir dos o más estructuras de Lewis con la misma disposición de los átomos en una molécula o un ion, la distribución real de los electrones es una media de la que muestran las distintas estructuras de Lewis. La distribución real de electrones en cada uno de los enlaces nitrógeno-oxígeno en es la media de un doble enlace y un enlace simple. Llamamos a las estructuras individuales de Lewis formas de resonancia. La estructura electrónica real de la molécula (la media de las formas de resonancia) se denomina híbrido de resonancia de las formas de resonancia individuales. Una flecha de doble punta entre las estructuras de Lewis indica que son formas de resonancia.
Debemos recordar que una molécula descrita como un híbrido de resonancia nunca posee una estructura electrónica descrita por cualquiera de las dos formas de resonancia. No fluctúa entre las formas de resonancia, sino que la estructura electrónica real es siempre la media de la que muestran todas las formas de resonancia. George Wheland, uno de los pioneros de la teoría de la resonancia, utilizó una analogía histórica para describir la relación entre las formas de resonancia y los híbridos de resonancia. Un viajero medieval, que nunca había visto un rinoceronte, lo describió como un híbrido de dragón y unicornio porque tenía muchas características en común con ambos. Así como un rinoceronte no es un dragón a veces ni un unicornio en otras ocasiones, un híbrido de resonancia no es ninguna de sus formas de resonancia en un momento dado. Al igual que el rinoceronte, es una entidad real cuya existencia ha sido demostrada por pruebas experimentales. Tiene algunas características en común con sus formas de resonancia, pero las propias formas de resonancia son imágenes convenientes e imaginarias (como el unicornio y el dragón).
El anión carbonato, ofrece un segundo ejemplo de resonancia:
Un átomo de oxígeno debe tener un doble enlace con el carbono para completar el octeto en el átomo central. Sin embargo, todos los átomos de oxígeno son equivalentes, y el doble enlace podría formarse a partir de cualquiera de los tres átomos. Esto da lugar a tres formas de resonancia del ion carbonato. Como podemos escribir tres estructuras de resonancia idénticas, sabemos que la disposición real de los electrones en el ion carbonato es la media de las tres estructuras. De nuevo, los experimentos muestran que los tres enlaces C-O son exactamente iguales.
### Conceptos clave y resumen
En una estructura de Lewis, se pueden asignar cargas formales a cada átomo tratando cada enlace como si la mitad de los electrones estuvieran asignados a cada átomo. Estas cargas formales hipotéticas son una guía para determinar la estructura Lewis más adecuada. Es preferible una estructura en la que las cargas formales sean lo más cercanas a cero posible. La resonancia se produce en los casos en los que se pueden escribir dos o más estructuras de Lewis con idéntica disposición de los átomos pero diferente distribución de los electrones. La distribución real de electrones (el híbrido de resonancia) es la media de la distribución indicada por las estructuras individuales de Lewis (las formas de resonancia).
### Ecuaciones clave
### Ejercicios de fin de capítulo de Química
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# Enlace químico y geometría molecular
## Fuerza de los enlaces iónicos y covalentes
La fuerza de un enlace describe la fuerza con la que cada átomo está unido a otro átomo y, por tanto, cuánta energía se necesita para romper el enlace entre ambos. En esta sección, aprenderá sobre la fuerza de enlace de los enlaces covalentes, para luego compararla con la fuerza de los enlaces iónicos, que está relacionada con la energía de red de un compuesto.
### Fuerza de adhesión: enlaces covalentes
Las moléculas estables existen porque los enlaces covalentes mantienen los átomos unidos. Medimos la fuerza de un enlace covalente por la energía necesaria para romperlo, es decir, la energía necesaria para separar los átomos enlazados. La separación de todo par de átomos enlazados requiere energía (consulte la ). Cuanto más fuerte sea un enlace, mayor será la energía necesaria para romperlo.
La energía necesaria para romper un enlace covalente específico en un mol de moléculas gaseosas se denomina energía de enlace o energía de disociación del enlace. La energía de enlace para una molécula diatómica, DX–Y, se define como el cambio de entalpía estándar en la reacción endotérmica:
Por ejemplo, la energía de enlace del enlace covalente puro H-H, DH–H, es de 436 kJ por mol de enlaces H-H rotos:
Las moléculas con tres o más átomos tienen dos o más enlaces. La suma de todas las energías de enlace en dicha molécula es igual al cambio de entalpía estándar para la reacción endotérmica que rompe todos los enlaces en la molécula. Por ejemplo, la suma de las cuatro energías de enlace C-H en el CH4, 1660 kJ, es igual al cambio de entalpía estándar de la reacción:
La energía media del enlace C-H, DC–H, es de 1660/4 = 415 kJ/mol porque hay cuatro moles de enlaces C-H rotos por mol de la reacción. Aunque los cuatro enlaces C-H son equivalentes en la molécula original, cada uno no requiere la misma energía para romperse; una vez que se rompe el primer enlace (que requiere 439 kJ/mol), los enlaces restantes son más fáciles de romper. El valor de 415 kJ/mol es la media, no el valor exacto necesario para romper un enlace cualquiera.
La fuerza de un enlace entre dos átomos aumenta a medida que aumenta el número de pares de electrones en el enlace. Por lo general, a medida que aumenta la resistencia del enlace, su longitud disminuye. Así, encontramos que los enlaces triples son más fuertes y más cortos que los enlaces dobles entre los mismos dos átomos; asimismo, los enlaces dobles son más fuertes y más cortos que los enlaces simples entre los mismos dos átomos. Las energías de enlace medias de algunos enlaces comunes aparecen en la , y una comparación de las longitudes y resistencias de enlace de algunos enlaces comunes aparece en la . Cuando un átomo se une a varios átomos de un grupo, la fuerza del enlace suele disminuir a medida que descendemos en el grupo. Por ejemplo, C-F es 439 kJ/mol, C-Cl es 330 kJ/mol y C-Br es 275 kJ/mol.
Podemos utilizar las energías de enlace para calcular los cambios de entalpía aproximados para las reacciones en las que no se dispone de entalpías de formación. Los cálculos de este tipo también nos dirán si una reacción es exotérmica o endotérmica. Una reacción exotérmica (ΔH negativo, calor producido) resulta cuando los enlaces en los productos son más fuertes que los enlaces en los reactivos. Una reacción endotérmica (ΔH positivo, calor absorbido) se produce cuando los enlaces de los productos son más débiles que los de los reactivos.
El cambio de entalpía, ΔH, en una reacción química es aproximadamente igual a la suma de la energía necesaria para romper todos los enlaces en los reactivos (energía "dentro", signo positivo) más la energía liberada cuando se forman todos los enlaces en los productos (energía "fuera", signo negativo). Esto se puede expresar matemáticamente de la siguiente manera:
En esta expresión, el símbolo Ʃ significa "la suma de" y D representa la energía de enlace en kilojulios por mol, que siempre es un número positivo. La energía de enlace se obtiene a partir de una tabla (como la ) y dependerá de que el enlace sea simple, doble o triple. Por lo tanto, al calcular las entalpías de esta manera, es importante que tengamos en cuenta el enlace en todos los reactivos y productos. Como los valores de D suelen ser promedios para un tipo de enlace en muchas moléculas diferentes, este cálculo proporciona una estimación aproximada, no un valor exacto, de la entalpía de reacción.
Considere la siguiente reacción:
o
Para formar dos moles de HCl, hay que romper un mol de enlaces H-H y un mol de enlaces Cl-Cl. La energía necesaria para romper estos enlaces es la suma de la energía de enlace del enlace H-H (436 kJ/mol) y del enlace Cl-Cl (243 kJ/mol). Durante la reacción, se forman dos moles de enlaces H-Cl (energía de enlace = 432 kJ/mol), liberando 2 432 kJ; o 864 kJ. Como los enlaces de los productos son más fuertes que los de los reactivos, la reacción libera más energía de la que consume:
Este exceso de energía se libera en forma de calor, por lo que la reacción es exotérmica. El Apéndice G da un valor para la entalpía molar estándar de formación del HCl(g), de –92,307 kJ/mol. El doble de ese valor es -184,6 kJ, lo que coincide con la respuesta que se obtuvo anteriormente para la formación de dos moles de HCl.
### Fuerza de enlace iónico y energía de red
Un compuesto iónico es estable debido a la atracción electrostática entre sus iones positivos y negativos. La energía de red de un compuesto es una medida de la fuerza de esta atracción. La energía de red (Δ de un compuesto iónico se define como la energía necesaria para separar un mol del sólido en sus iones gaseosos componentes. En el sólido iónico MX, la energía de red es el cambio de entalpía del proceso:
Tenga en cuenta que estamos utilizando la convención en la que el sólido iónico se separa en iones, por lo que nuestras energías de red serán endotérmicas (valores positivos). Algunos textos utilizan la convención equivalente pero opuesta que la energía de red como la energía liberada cuando los iones separados se combinan para formar una red y dando valores negativos (exotérmicos). Por lo tanto, si busca energías de red en otra referencia, asegúrese de comprobar qué definición se utiliza. En ambos casos, una magnitud mayor para la energía de red indica un compuesto iónico más estable. En el cloruro de sodio, ΔHred = 769 kJ. Así, se necesitan 769 kJ para separar un mol de NaCl sólido en iones gaseosos Na+ y Cl–. Cuando un mol de cada uno de los iones gaseosos Na+ y Cl– forman el NaCl sólido, se liberan 769 kJ de calor.
La energía de red ΔHred de un cristal iónico puede expresarse mediante la siguiente ecuación (derivada de la ley de Coulomb, que rige las fuerzas entre cargas eléctricas):
en la que C es una constante que depende del tipo de estructura cristalina; Z+ y Z– son las cargas de los iones; y Ro es la distancia interiónica (la suma de los radios de los iones positivos y negativos). Así, la energía de red de un cristal iónico aumenta rápidamente a medida que las cargas de los iones aumentan y los tamaños de los iones disminuyen. Cuando todos los demás parámetros se mantienen constantes, duplicar la carga del catión y del anión cuadruplica la energía de la red. Por ejemplo, la energía de red del LiF (Z+ y Z– = 1) es de 1023 kJ/mol, mientras que la del MgO (Z+ y Z– = 2) es de 3900 kJ/mol el (RRo es casi el mismo, alrededor de 200 pm para ambos compuestos).
Diferentes distancias interatómicas producen diferentes energías de red. Por ejemplo, podemos comparar la energía de red del MgF2 (2957 kJ/mol) con la del MgI2 (2327 kJ/mol) para observar el efecto en la energía de red del menor tamaño iónico del F– en comparación con el I–.
### El ciclo Born-Haber
No es posible medir directamente las energías de la red. Sin embargo, la energía de red puede calcularse utilizando la ecuación dada en la sección anterior o utilizando un ciclo termoquímico. El ciclo de Born-Haber es una aplicación de la ley de Hess que descompone la formación de un sólido iónico en una serie de pasos individuales:
1. la entalpía estándar de formación del compuesto
2. IE, la energía de ionización del metal
3. EA, la afinidad electrónica del no metal
4. la entalpía de sublimación del metal
5. D, la energía de disociación del enlace del no metal
6. ΔHred, la energía de red del compuesto
La muestra un diagrama del ciclo de Born-Haber para la formación de fluoruro de cesio sólido.
Comenzamos con los elementos en sus estados más comunes, Cs(s) y F2(g). El representa la conversión del cesio sólido en gas, y luego la energía de ionización convierte los átomos de cesio gaseoso en cationes. En el siguiente paso, contabilizamos la energía necesaria para romper el enlace F-F y producir átomos de flúor. La conversión de un mol de átomos de flúor en iones de flúor es un proceso exotérmico, por lo que este paso desprende energía (la afinidad electrónica) y se muestra como decreciente a lo largo del eje y. Ahora tenemos un mol de cationes Cs y un mol de aniones F. Estos iones se combinan para producir fluoruro de cesio sólido. El cambio de entalpía en este paso es el negativo de la energía de red, por lo que también es una cantidad exotérmica. La energía total implicada en esta conversión es igual a la entalpía de formación determinada experimentalmente, del compuesto a partir de sus elementos. En este caso, el cambio global es exotérmico.
La ley de Hess también puede utilizarse para mostrar la relación entre las entalpías de los pasos individuales y la entalpía de formación. La lo muestra para el fluoruro, CsF.
Así, la energía de la red puede calcularse a partir de otros valores. Para el fluoruro de cesio, utilizando estos datos, la energía de red es:
El ciclo de Born-Haber también puede utilizarse para calcular cualquiera de las otras cantidades de la ecuación de la energía de la red, siempre que se conozca el resto. Por ejemplo, si la entalpía de sublimación relevante la energía de ionización (IE), la entalpía de disociación de enlace (D), la energía de red ΔHred, y la entalpía estándar de formación se conocen, el ciclo de Born-Haber puede utilizarse para determinar la afinidad electrónica de un átomo.
Las energías de red calculadas para los compuestos iónicos suelen ser mucho más altas que las energías de disociación de los enlaces medidos para los enlaces covalentes. Mientras que las energías de red suelen situarse en el rango de 600–4.000 kJ/mol (algunas incluso más altas), las energías de disociación de los enlaces covalentes suelen estar entre 150–400 kJ/mol para los enlaces simples. Sin embargo, hay que tener en cuenta que no son valores directamente comparables. En el caso de los compuestos iónicos, las energías de red están asociadas a muchas interacciones, ya que los cationes y los aniones se agrupan en una red extendida. En los enlaces covalentes, la energía de disociación del enlace está asociada a la interacción de solo dos átomos.
### Conceptos clave y resumen
La fuerza de un enlace covalente se mide por su energía de disociación del enlace, es decir, la cantidad de energía necesaria para romper ese enlace concreto en un mol de moléculas. Los enlaces múltiples son más fuertes que los enlaces simples entre los mismos átomos. La entalpía de una reacción puede estimarse a partir del aporte de energía necesario para romper los enlaces y la energía liberada cuando se forman nuevos enlaces. En los enlaces iónicos, la energía de red es la energía necesaria para separar un mol de un compuesto en sus iones en fase gaseosa. La energía de la red aumenta en los iones con cargas más altas y distancias más cortas entre los iones. Las energías de red se calculan a menudo utilizando el ciclo de Born-Haber, un ciclo termoquímico que incluye todos los pasos energéticos implicados en la conversión de elementos en un compuesto iónico.
### Ecuaciones clave
### Ejercicios de fin de capítulo de Química
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# Enlace químico y geometría molecular
## Estructura molecular y polaridad
Hasta ahora, hemos utilizado estructuras bidimensionales de Lewis para representar moléculas. Sin embargo, la estructura molecular es en realidad tridimensional, y es importante poder describir los enlaces moleculares en términos de sus distancias, ángulos y disposiciones relativas en el espacio (). Un ángulo de enlace es el ángulo entre dos enlaces cualesquiera que incluyen un átomo común, normalmente medido en grados. Una distancia de enlace (o longitud de enlace) es la distancia entre los núcleos de dos átomos enlazados a lo largo de la línea recta que une los núcleos. Las distancias de enlace se miden en Ångstroms (1 Å = 10–10 m) o picómetros (1 pm = 10–12 m, 100 pm = 1 Å).
### Teoría VSEPR
La teoría de repulsión de pares de electrones de la capa de valencia (teoría VSEPR) nos permite predecir la estructura molecular, lo que incluye los ángulos de enlace aproximados alrededor de un átomo central de una molécula a partir de un examen del número de enlaces y pares solitarios de electrones en su estructura de Lewis. El modelo VSEPR asume que los pares de electrones en la capa de valencia de un átomo central adoptarán una disposición que minimice las repulsiones entre estos pares de electrones maximizando la distancia entre ellos. Los electrones de la capa de valencia de un átomo central forman pares de electrones enlazados, situados principalmente entre átomos enlazados, o pares solitarios. La repulsión electrostática de estos electrones se reduce cuando las distintas regiones de alta densidad electrónica asumen posiciones lo más alejadas posible entre sí.
La teoría VSEPR predice la disposición de los pares de electrones alrededor de cada átomo central y, normalmente, la disposición correcta de los átomos en una molécula. Sin embargo, debemos entender que la teoría solo considera las repulsiones de pares de electrones. Otras interacciones, como las repulsiones nuclear-nuclear y las atracciones nuclear-electrónica, también intervienen en la disposición final que adoptan los átomos en una determinada estructura molecular.
Como ejemplo sencillo de la teoría VSEPR, predigamos la estructura de una molécula gaseosa de BeF2. La estructura de Lewis del BeF2 () muestra solo dos pares de electrones alrededor del átomo central de berilio. Con dos enlaces y sin pares solitarios de electrones en el átomo central, los enlaces están lo más separados posible, y la repulsión electrostática entre estas regiones de alta densidad electrónica se reduce al mínimo cuando están en lados opuestos del átomo central. El ángulo de enlace es de 180° ().
La ilustra esta y otras geometrías de pares de electrones que minimizan las repulsiones entre regiones de alta densidad de electrones (enlaces o pares solitarios). Dos regiones de densidad de electrones alrededor de un átomo central en una molécula forman una geometría lineal; tres regiones forman una geometría trigonal plana; cuatro regiones forman una geometría tetraédrica; cinco regiones forman una geometría trigonal bipiramidal; y seis regiones forman una geometría octaédrica.
### Geometría de pares de electrones frente a la estructura molecular
Es importante señalar que la geometría de pares de electrones alrededor de un átomo central no es lo mismo que su estructura molecular. Las geometrías de pares de electrones mostradas en la describen todas las regiones donde se encuentran los electrones, tanto los enlaces como los pares solitarios. La estructura molecular describe la ubicación de los átomos, no de los electrones.
Diferenciamos estas dos situaciones denominando la geometría que incluye todos los pares de electrones como geometría de pares de electrones. La estructura que incluye solo la colocación de los átomos en la molécula se llama estructura molecular. Las geometrías de los pares de electrones serán las mismas que las de las estructuras moleculares cuando no haya pares solitarios de electrones alrededor del átomo central, pero serán diferentes cuando haya pares solitarios presentes en el átomo central.
Por ejemplo, la molécula de metano, CH4, que es el principal componente del gas natural, tiene cuatro pares de electrones de enlace alrededor del átomo central de carbono; la geometría de pares de electrones es tetraédrica, al igual que la estructura molecular (). Por otro lado, la molécula de amoníaco, NH3, también tiene cuatro pares de electrones asociados al átomo de nitrógeno, por lo que tiene una geometría tetraédrica de pares de electrones. Una de estas regiones, sin embargo, es un par solitario, que no está incluido en la estructura molecular, y este par solitario influye en la forma de la molécula ().
Como se ve en la , las pequeñas distorsiones de los ángulos ideales en la pueden ser el resultado de las diferencias de repulsión entre varias regiones de densidad de electrones. La teoría VSEPR predice estas distorsiones al establecer un orden de repulsiones y un orden de la cantidad de espacio ocupado por los diferentes tipos de pares de electrones. El orden de las repulsiones de pares de electrones de mayor a menor repulsión es:
Este orden de repulsiones determina la cantidad de espacio que ocupan las diferentes regiones de electrones. Un par de electrones solitario ocupa una región de espacio mayor que los electrones de un triple enlace; a su vez, los electrones de un triple enlace ocupan más espacio que los de un doble enlace, y así sucesivamente. El orden de los tamaños de mayor a menor es:
Pensemos en el formaldehído, H2CO, que se utiliza como conservante de muestras biológicas y anatómicas (). Esta molécula tiene regiones de alta densidad electrónica que consisten en dos enlaces simples y un doble enlace. La geometría básica es trigonal plana con ángulos de enlace de 120°, pero vemos que el doble enlace provoca ángulos ligeramente mayores (121°), y el ángulo entre los enlaces simples es ligeramente menor (118°).
En la molécula de amoníaco, los tres átomos de hidrógeno unidos al nitrógeno central no están dispuestos en una estructura molecular plana y trigonal, sino en una pirámide trigonal tridimensional () con el átomo de nitrógeno en el vértice y los tres átomos de hidrógeno formando la base. Los ángulos de enlace ideales en una pirámide trigonal se basan en la geometría de pares de electrones tetraédrica. De nuevo, hay ligeras desviaciones del ideal porque los pares solitarios ocupan regiones del espacio más grandes que los electrones de enlace. Los ángulos de enlace H–N–H en el NH3 son ligeramente más pequeños que el ángulo de 109,5° en un tetraedro regular () porque la repulsión par solitario-par enlazante es mayor que la repulsión par enlazante-par enlazante (). La ilustra las estructuras moleculares ideales, que se predicen con base en las geometrías de pares de electrones para varias combinaciones de pares solitarios y pares enlazantes.
Según la teoría VSEPR, las ubicaciones de los átomos terminales (Xs en la ) son equivalentes dentro de las geometrías de pares de electrones lineales, trigonales planas y tetraédricas (las tres primeras filas de la tabla). No importa qué X se sustituya por un par solitario porque las moléculas pueden girar para convertir posiciones. Sin embargo, en las geometrías bipiramidales trigonales de pares de electrones, hay dos posiciones X distintas, como se muestra en la : una posición axial (si sostenemos un modelo de bipirámide trigonal por las dos posiciones axiales, tenemos un eje alrededor del cual podemos girar el modelo) y una posición ecuatorial (tres posiciones forman un ecuador alrededor del centro de la molécula). Como se muestra en la , la posición axial está rodeada de ángulos de enlace de 90°, mientras que la posición ecuatorial tiene más espacio disponible debido a los ángulos de enlace de 120°. En una geometría bipiramidal trigonal de pares de electrones, los pares solitarios siempre ocupan posiciones ecuatoriales porque estas posiciones más espaciosas pueden acomodar más fácilmente los pares solitarios más grandes.
Teóricamente, podemos encontrar tres posibles disposiciones para los tres enlaces y los dos pares solitarios de la molécula de ClF3 (). La estructura estable es la que coloca los pares solitarios en posiciones ecuatoriales, dando una estructura molecular en forma de T.
Cuando un átomo central tiene dos pares solitarios de electrones y cuatro regiones de enlace, tenemos una geometría octaédrica de pares de electrones. Los dos pares solitarios se encuentran en lados opuestos del octaedro (separados 180°), lo que produce una estructura molecular cuadrada y plana que minimiza las repulsiones entre pares solitarios ().
### Predicción de la geometría de pares de electrones y de la estructura molecular
El siguiente procedimiento utiliza la teoría VSEPR para determinar las geometrías de los pares de electrones y las estructuras moleculares:
1. Escriba la estructura de Lewis de la molécula o del ion poliatómico.
2. Cuente el número de regiones de densidad de electrones (pares solitarios y enlaces) alrededor del átomo central. Un enlace simple, doble o triple cuenta como una región de densidad electrónica.
3. Identifique la geometría de pares de electrones en función del número de regiones de densidad electrónica: lineal, trigonal plana, tetraédrica, bipiramidal trigonal u octaédrica (, primera columna).
4. Utilice el número de pares solitarios para determinar la estructura molecular (). Si es posible más de una disposición de pares solitarios y enlaces químicos, elija la que minimice las repulsiones, recordando que los pares solitarios ocupan más espacio que los enlaces múltiples, que a su vez ocupan más espacio que los enlaces simples. En los arreglos bipiramidales trigonales, la repulsión se minimiza cuando cada par solitario está en una posición ecuatorial. En una disposición octaédrica con dos pares solitarios, la repulsión se minimiza cuando los pares solitarios están en lados opuestos del átomo central.
Los siguientes ejemplos ilustran el uso de la teoría VSEPR para predecir la estructura molecular de moléculas o iones que no tienen pares solitarios de electrones. En este caso, la estructura molecular es idéntica a la geometría de pares de electrones.
Los siguientes ejemplos ilustran el efecto de los pares solitarios de electrones en la estructura molecular.
### Estructura molecular para moléculas multicéntricas
Cuando una molécula o un ion poliatómico tiene un solo átomo central, la estructura molecular describe completamente la forma de la molécula. Las moléculas más grandes no tienen un único átomo central, sino que están conectadas por una cadena de átomos interiores que poseen cada uno una geometría "local". El modo en que estas estructuras locales se orientan entre sí también influye en la forma molecular, pero estas consideraciones están más allá del alcance de esta discusión introductoria. Para nuestros fines, solo nos centraremos en determinar las estructuras locales.
### Polaridad molecular y momento dipolar
Como se comentó anteriormente, los enlaces covalentes polares conectan dos átomos con diferentes electronegatividades, dejando un átomo con una carga parcial positiva (δ+) y el otro átomo con una carga parcial negativa (δ-), ya que los electrones son atraídos hacia el átomo más electronegativo. Esta separación de cargas da lugar a un momento dipolar de enlace. La magnitud de un momento dipolar de enlace se representa con la letra griega mu (µ) y viene dada por la fórmula que se muestra aquí, donde Q es la magnitud de las cargas parciales (determinada por la diferencia de electronegatividad) y r es la distancia entre las cargas:
Este momento de enlace puede representarse como un vector, una cantidad que tiene tanto dirección como magnitud (). Los vectores dipolo se muestran como flechas que apuntan a lo largo del enlace desde el átomo menos electronegativo hacia el átomo más electronegativo. Se dibuja un pequeño signo más en el extremo menos electronegativo para indicar el extremo parcialmente positivo del enlace. La longitud de la flecha es proporcional a la magnitud de la diferencia de electronegatividad entre los dos átomos.
Una molécula completa también puede tener una separación de carga, lo que depende de su estructura molecular y de la polaridad de cada uno de sus enlaces. Si existe tal separación de cargas, se dice que la molécula es una molécula polar (o dipolar); en caso contrario, se dice que la molécula es no polar. El momento dipolar mide el grado de separación de cargas netas en la molécula en su conjunto. Determinamos el momento dipolar sumando los momentos de enlace en el espacio tridimensional, teniendo en cuenta la estructura molecular.
En las moléculas diatómicas solo hay un enlace, por lo que su momento dipolar de enlace determina la polaridad molecular. Las moléculas diatómicas homonucleares como el Br2 y el N2 no tienen diferencia de electronegatividad, por lo que su momento dipolar es nulo. En las moléculas heteronucleares, como el CO, existe un pequeño momento dipolar. En el caso del HF, hay un momento dipolar mayor porque hay una mayor diferencia de electronegatividad.
Cuando una molécula contiene más de un enlace, hay que tener en cuenta la geometría. Si los enlaces de una molécula están dispuestos de tal manera que sus momentos de enlace se cancelan (la suma de vectores es igual a cero), entonces la molécula es no polar. Esta es la situación del CO2 (). Cada uno de los enlaces es polar, pero la molécula en su conjunto es no polar. A partir de la estructura de Lewis, y utilizando la teoría VSEPR, determinamos que la molécula de CO2 es lineal con enlaces polares C=O en lados opuestos del átomo de carbono. Los momentos de enlace se cancelan porque apuntan en direcciones opuestas. En el caso de la molécula de agua (), la estructura de Lewis muestra otra vez que hay dos enlaces a un átomo central, y la diferencia de electronegatividad muestra de nuevo que cada uno de estos enlaces tiene un momento de enlace distinto de cero. En este caso, no obstante, la estructura molecular está doblada debido a los pares solitarios del O, y los dos momentos de enlace no se cancelan. Por lo tanto, el agua sí tiene un momento dipolar neto y es una molécula polar (dipolo).
La molécula de OCS tiene una estructura similar a la del CO2, pero un átomo de azufre sustituyó uno de los átomos de oxígeno. Para determinar si esta molécula es polar, dibujamos la estructura molecular. La teoría VSEPR predice una molécula lineal:
El enlace C-O es considerablemente polar. Aunque el C y el S tienen valores de electronegatividad muy similares, el S es ligeramente más electronegativo que el C, por lo que el enlace C-S es ligeramente polar. Como el oxígeno es más electronegativo que el azufre, el extremo de oxígeno de la molécula es el extremo negativo.
El clorometano, CH3Cl, es una molécula tetraédrica con tres enlaces C-H ligeramente polares y un enlace C-Cl más polar. Las electronegatividades relativas de los átomos enlazados son H < C < Cl, por lo que todos los momentos de enlace apuntan hacia el extremo Cl de la molécula y se suman para producir un momento dipolar considerable (las moléculas son relativamente polares).
Para las moléculas de alta simetría como el BF3 (trigonal plana), el CH4 (tetraédrica), el PF5 (bipiramidal trigonal) y el SF6 (octaédrica), todos los enlaces tienen la misma polaridad (mismo momento de enlace) y se orientan en geometrías que dan lugar a moléculas no polares (el momento dipolar es cero). Sin embargo, las moléculas de menor simetría geométrica pueden ser polares incluso cuando todos los momentos de enlace son idénticos. En estas moléculas, las direcciones de los momentos de enlace iguales son tales que se suman para dar un momento dipolar no nulo y una molécula polar. Algunos ejemplos de estas moléculas son el sulfuro de hidrógeno, H2S (no lineal), y el amoníaco, NH3 (piramidal trigonal).
En resumen, para ser polar, una molécula debe:
1. Tener al menos un enlace covalente polar.
2. Tener una estructura molecular tal que la suma de los vectores de cada momento dipolar de enlace no se cancele.
### Propiedades de las moléculas polares
Las moléculas polares tienden a alinearse cuando se colocan en un campo eléctrico con el extremo positivo de la molécula orientado hacia la placa negativa y el extremo negativo hacia la placa positiva (). Podemos utilizar un objeto cargado eléctricamente para atraer moléculas polares, pero las moléculas no polares no son atraídas. Además, los solventes polares son mejores para disolver sustancias polares, y los disolventes no polares son mejores para disolver sustancias no polares.
### Conceptos clave y resumen
La teoría VSEPR predice la disposición tridimensional de los átomos en una molécula. Establece que los electrones de valencia asumirán una geometría de pares de electrones que minimiza las repulsiones entre las áreas de alta densidad de electrones (enlaces o pares solitarios). La estructura molecular, que se refiere solo a la colocación de los átomos en una molécula y no a los electrones, es equivalente a la geometría de pares de electrones solo cuando no hay pares solitarios de electrones alrededor del átomo central. Un momento dipolar mide una separación de carga. Para un enlace, el momento dipolar de enlace está determinado por la diferencia de electronegatividad entre los dos átomos. En una molécula, el momento dipolar global viene determinado tanto por los momentos de enlace individuales como por la disposición de estos dipolos en la estructura molecular. Las moléculas polares (las que tienen un momento dipolar apreciable) interactúan con los campos eléctricos, mientras que las moléculas no polares no lo hacen.
### Ejercicios de fin de capítulo de Química
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# Teorías avanzadas del enlace covalente
## Introducción
Hemos examinado las ideas básicas del enlace, mostrando que los átomos comparten electrones para formar moléculas con estructuras de Lewis estables y que podemos predecir las formas de esas moléculas mediante la teoría de repulsión de pares de electrones de la capa de valencia (VSEPR). Estas ideas proporcionan un importante punto de partida para entender el enlace químico. Pero estos modelos a veces se quedan cortos en su capacidad para predecir el comportamiento de las sustancias reales. ¿Cómo podemos conciliar las geometrías de los orbitales atómicos s, p, y d con las formas moleculares que muestran ángulos como 120° y 109,5°? Además, sabemos que los electrones y el comportamiento magnético están relacionados a través de los campos electromagnéticos. Tanto el N2 como el O2 tienen estructuras Lewis bastante similares que contienen pares solitarios de electrones.
Sin embargo, el oxígeno muestra un comportamiento magnético muy diferente al del nitrógeno. Podemos verter nitrógeno líquido a través de un campo magnético sin que se produzcan interacciones visibles, mientras que el oxígeno líquido (mostrado en la ) es atraído por el imán y flota en el campo magnético. Necesitamos entender los conceptos adicionales de la teoría del enlace de valencia, la hibridación de orbitales y la teoría de orbitales moleculares para comprender estas observaciones. |
# Teorías avanzadas del enlace covalente
## Teoría de enlace de valencia
Como sabemos, una teoría científica es una explicación firmemente respaldada de las leyes naturales observadas o de grandes conjuntos de datos experimentales. Para ser aceptada, una teoría debe explicar los datos experimentales y ser capaz de predecir comportamientos. Por ejemplo, la teoría VSEPR ha sido ampliamente aceptada porque predice formas moleculares tridimensionales coherentes con los datos experimentales recopilados de miles de moléculas diferentes. Sin embargo, la teoría VSEPR no proporciona una explicación del enlace químico.
Existen teorías exitosas que describen la estructura electrónica de los átomos. Podemos utilizar la mecánica cuántica para predecir las regiones específicas alrededor de un átomo donde es probable que se encuentren los electrones: Una forma esférica para un orbital s, una forma de campana para un orbital p, etc. Sin embargo, estas predicciones solo describen los orbitales alrededor de los átomos libres. Cuando los átomos se unen para formar moléculas, los orbitales atómicos no son suficientes para describir las regiones donde se ubicarán los electrones en la molécula. Una comprensión más completa de las distribuciones de electrones requiere un modelo que pueda dar cuenta de la estructura electrónica de las moléculas. Una teoría popular sostiene que un enlace covalente se forma cuando un par de electrones es compartido por dos átomos y es atraído simultáneamente por los núcleos de ambos átomos. En las siguientes secciones, analizaremos cómo se describen dichos enlaces mediante la teoría del enlace de valencia y la hibridación.
La teoría del enlace de valencia describe un enlace covalente como la superposición de orbitales atómicos medio llenos (cada uno de los cuales contiene un solo electrón) que generan un par de electrones compartidos entre los dos átomos enlazados. Decimos que los orbitales de dos átomos diferentes se superponen cuando una porción de un orbital y una porción de un segundo orbital ocupan la misma región del espacio. Según la teoría del enlace de valencia, un enlace covalente se produce cuando se cumplen dos condiciones: (1) un orbital de un átomo se superpone con un orbital de un segundo átomo y (2) los electrones individuales de cada orbital se combinan para formar un par de electrones. La atracción mutua entre este par de electrones cargados negativamente y los núcleos cargados positivamente de los dos átomos sirve para unir físicamente los dos átomos mediante una fuerza que definimos como enlace covalente. La fuerza de un enlace covalente depende del grado de superposición de los orbitales implicados. Los orbitales que se superponen mucho forman enlaces más fuertes que los que se superponen menos.
La energía del sistema depende del grado de superposición de los orbitales. La ilustra cómo cambia la suma de las energías de dos átomos de hidrógeno (la curva coloreada) a medida que se acercan. Cuando los átomos están muy separados no hay superposición, y por convención fijamos la suma de las energías en cero. A medida que los átomos se mueven juntos, sus orbitales comienzan a superponerse. Cada electrón comienza a sentir la atracción del núcleo del otro átomo. Además, los electrones comienzan a repelerse entre sí, al igual que los núcleos. Aunque los átomos siguen estando muy separados, las atracciones son ligeramente más fuertes que las repulsiones y la energía del sistema disminuye (se empieza a formar un vínculo). A medida que los átomos se acercan, la superposición aumenta, por lo que la atracción de los núcleos por los electrones sigue aumentando (al igual que las repulsiones entre los electrones y entre los núcleos). A cierta distancia específica entre los átomos, que varía en función de los átomos involucrados, la energía alcanza su valor más bajo (más estable). Esta distancia óptima entre los dos núcleos enlazados es la longitud de enlace entre los dos átomos. El enlace es estable porque en este punto, las fuerzas de atracción y repulsión se combinan para crear la configuración de menor energía posible. Si la distancia entre los núcleos disminuyera aún más, las repulsiones entre los núcleos y las repulsiones al estar los electrones confinados más cerca unos de otros serían más fuertes que las fuerzas de atracción. La energía del sistema aumentaría entonces (haciendo que el sistema se desestabilice), como se muestra en el extremo izquierdo de la .
La energía de enlace es la diferencia entre el mínimo energético (que se produce en la longitud de enlace) y la energía de los dos átomos separados. Es la cantidad de energía liberada cuando se forma el enlace. A la inversa, se requiere la misma cantidad de energía para romper el enlace. En la molécula de H2 que se muestra en la , a la distancia de enlace de 74 pm el sistema es de 7,24 10−19 J menor en energía que los dos átomos de hidrógeno separados. Esto puede parecer una cifra pequeña. Sin embargo, sabemos por nuestra anterior descripción de la termoquímica que las energías de los enlaces se discuten a menudo sobre una base por mol. Por ejemplo, requiere 7,24 10−19 para romper un enlace H-H, pero se necesitan 4,36 105 J para romper 1 mol de enlaces H-H. En la se muestra una comparación de algunas longitudes y energías de enlace. Podemos encontrar muchos de estos enlaces en una gran variedad de moléculas, y esta tabla proporciona valores medios. Por ejemplo, la rotura del primer enlace C-H en CH4 requiere 439,3 kJ/mol, mientras que la rotura del primer enlace C-H en H-CH2C6H5 (un diluyente de pintura común) requiere 375,5 kJ/mol.
Además de la distancia entre dos orbitales, la orientación de estos también afecta a su superposición (salvo en el caso de dos orbitales s, que son esféricamente simétricos). Es posible una mayor superposición cuando los orbitales están orientados de tal manera que se superponen en una línea directa entre los dos núcleos. La ilustra esto en dos orbitales p de diferentes átomos; la superposición es mayor cuando los orbitales se superponen de extremo a extremo en lugar de en ángulo.
La superposición de dos orbitales s (como en el H2), la superposición de un orbital s y un orbital p (como en el HCl) y la superposición de extremo a extremo de dos orbitales p (como en el Cl2) producen enlaces sigma (enlaces σ), como se muestra en la . Un enlace σ es un enlace covalente en el que la densidad electrónica se concentra en la región a lo largo del eje internuclear; es decir, una línea entre los núcleos pasaría por el centro de la región de superposición. Los enlaces simples en las estructuras de Lewis se describen como enlaces σ en la teoría del enlace de valencia.
Un enlace pi (enlace π) es un tipo de enlace covalente que resulta de la superposición lado a lado de dos orbitales p, como se muestra en la . En un enlace π, las regiones de superposición orbital se encuentran en lados opuestos del eje internuclear. A lo largo del propio eje, hay un nodo, es decir, un plano sin probabilidad de encontrar un electrón.
Mientras que todos los enlaces simples son enlaces σ, los enlaces múltiples están formados por enlaces σ y π. Como sugieren las estructuras de Lewis de abajo, el O2 contiene un doble enlace y el N2 un triple enlace. El doble enlace está formado por un enlace σ y un enlace π, y el triple enlace está formado por un enlace σ y dos enlaces π. Entre dos átomos cualesquiera, el primer enlace formado será siempre un enlace σ, pero solo puede haber un enlace σ en cualquier ubicación. En todo enlace múltiple, habrá un enlace σ, y los restantes uno o dos enlaces serán enlaces π. Estos enlaces se describen con más detalle más adelante en este capítulo.
Como se ve en la , un enlace simple carbono-carbono tiene un promedio de 347 kJ/mol, mientras que en un doble enlace carbono-carbono, el enlace π aumenta la fuerza del enlace en 267 kJ/mol. La adición de un enlace π adicional produce un aumento adicional de 225 kJ/mol. Podemos ver un patrón similar cuando comparamos otros enlaces σ y π. Así, cada enlace π individual es generalmente más débil que un enlace σ correspondiente entre los mismos dos átomos. En un enlace σ, hay un mayor grado de superposición de orbitales que en un enlace π.
### Conceptos clave y resumen
La teoría del enlace de valencia describe el enlace como consecuencia de la superposición de dos orbitales atómicos separados en átomos diferentes que crea una región con un par de electrones compartidos entre los dos átomos. Cuando los orbitales se superponen a lo largo de un eje que contiene los núcleos, forman un enlace σ. Cuando se superponen de forma que se crea un nodo a lo largo de este eje, forman un enlace π.
### Ejercicios de fin de capítulo de Química
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# Teorías avanzadas del enlace covalente
## Orbitales atómicos híbridos
Pensar en términos de orbitales atómicos superpuestos es una forma de explicar cómo se forman los enlaces químicos en las moléculas diatómicas. Sin embargo, necesitamos un modelo más detallado para entender cómo las moléculas con más de dos átomos forman enlaces estables. Por ejemplo, consideremos la molécula de agua, en la que tenemos un átomo de oxígeno que se une a dos átomos de hidrógeno. El oxígeno tiene la configuración electrónica 1s22s22p4, con dos electrones no apareados (uno en cada uno de los dos orbitales 2p). La teoría de enlace de valencia predeciría que los dos enlaces O-H se forman a partir de la superposición de estos dos orbitales 2p con los orbitales 1s de los átomos de hidrógeno. Si ese fuera el caso, el ángulo de enlace sería de 90°, como se muestra en la , porque los orbitales p son perpendiculares entre sí. Las pruebas experimentales demuestran que el ángulo de enlace es de 104,5°, no de 90°. La predicción del modelo de la teoría del enlace de valencia no coincide con las observaciones del mundo real de una molécula de agua; se necesita un modelo diferente.
Los cálculos mecánico-cuánticos sugieren por qué los ángulos de enlace observados en el H2O difieren de los predichos por la superposición del orbital 1s de los átomos de hidrógeno con los orbitales 2p del átomo de oxígeno. La expresión matemática conocida como función de onda, ψ, contiene información sobre cada orbital y las propiedades ondulatorias de los electrones en un átomo aislado. Cuando los átomos se unen en una molécula, las funciones de onda se combinan para producir nuevas descripciones matemáticas que tienen formas diferentes. Este proceso de combinación de las funciones de onda de los orbitales atómicos se denomina hibridación y se realiza matemáticamente mediante la combinación lineal de orbitales atómicos, CLOA (una técnica que volveremos a encontrar más adelante). Los nuevos orbitales resultantes se denominan orbitales híbridos. Los orbitales de valencia en un átomo de oxígeno aislado son un orbital 2s y tres orbitales 2p. Los orbitales de valencia de un átomo de oxígeno en una molécula de agua son diferentes; consisten en cuatro orbitales híbridos equivalentes que apuntan aproximadamente hacia las esquinas de un tetraedro (). En consecuencia, la superposición de los orbitales O y H debería dar lugar a un ángulo de enlace tetraédrico (109,5°). El ángulo observado de 104,5° es una prueba experimental para la que los cálculos mecánico-cuánticos ofrecen una explicación útil: La teoría de enlace de valencia debe incluir un componente de hibridación para ofrecer predicciones precisas.
Las siguientes ideas son importantes para entender la hibridación:
1. Los orbitales híbridos no existen en los átomos aislados. Solo se forman en los átomos con enlaces covalentes.
2. Los orbitales híbridos tienen formas y orientaciones muy diferentes a las de los orbitales atómicos de los átomos aislados.
3. La combinación de orbitales atómicos produce un conjunto de orbitales híbridos. El número de orbitales híbridos en un conjunto es igual al número de orbitales atómicos que se combinaron para producir el conjunto.
4. Todos los orbitales de un conjunto de orbitales híbridos son equivalentes en forma y energía.
5. El tipo de orbitales híbridos que se forman en un átomo enlazado depende de su geometría de pares de electrones, tal y como predice la teoría VSEPR.
6. Los orbitales híbridos se superponen para formar enlaces σ. Los orbitales no hibridados se superponen para formar enlaces π.
En las siguientes secciones, discutiremos los tipos comunes de orbitales híbridos.
### sp Hibridación
El átomo de berilio de una molécula gaseosa de BeCl2 es un ejemplo de átomo central sin pares solitarios de electrones en una disposición lineal de tres átomos. Hay dos regiones de densidad electrónica de valencia en la molécula de BeCl2 que corresponden a los dos enlaces covalentes Be-Cl. Para acomodar estos dos dominios de electrones, dos de los cuatro orbitales de valencia del átomo de Be se mezclarán para dar lugar a dos orbitales híbridos. Este proceso de hibridación implica la mezcla del orbital de valencia s con uno de los orbitales de valencia p para dar lugar a dos equivalentes que se orientan en una geometría lineal (). En esta figura, el conjunto de orbitales sp parece tener una forma similar a la del orbital p original, pero hay una diferencia importante. El número de orbitales atómicos combinados siempre es igual al número de orbitales híbridos formados. El orbital p es un orbital que puede contener hasta dos electrones. El conjunto sp son dos orbitales equivalentes que apuntan a 180° el uno del otro. Los dos electrones que estaban originalmente en el orbital s se distribuyen ahora en los dos orbitales sp, que están medio llenos. En el BeCl2 gaseoso, estos orbitales híbridos medio llenos se superpondrán con los orbitales de los átomos de cloro para formar dos enlaces σ idénticos.
Ilustramos las diferencias electrónicas en un átomo de Be aislado y en el átomo de Be enlazado en el diagrama de niveles de energía orbital en la . Estos diagramas representan cada orbital mediante una línea horizontal (que indica su energía) y cada electrón mediante una flecha. La energía aumenta hacia la parte superior del diagrama. Utilizamos una flecha hacia arriba para indicar un electrón en un orbital y dos flechas (hacia arriba y hacia abajo) para indicar dos electrones de espín opuesto.
Cuando los orbitales atómicos se hibridan, los electrones de valencia ocupan los orbitales recién creados. El átomo de Be tenía dos electrones de valencia, por lo que cada uno de los orbitales sp recibe uno de estos electrones. Cada uno de estos electrones se empareja con el electrón no apareado de un átomo de cloro cuando un orbital híbrido y un orbital de cloro se superponen durante la formación de los enlaces Be-Cl.
Cualquier átomo central rodeado por solo dos regiones de densidad electrónica de valencia en una molécula mostrará hibridación sp. Otros ejemplos son el átomo de mercurio en la molécula lineal HgCl2, el átomo de zinc en Zn(CH3)2, que contiene una disposición lineal C-Zn-C, y los átomos de carbono en HCCH y CO2.
### hibridación sp2
Los orbitales de valencia de un átomo central rodeado de tres regiones de densidad electrónica están formados por un conjunto de tres orbitales híbridos y un orbital p no hibridado. Esta disposición resulta de la hibridación sp2, la mezcla de un orbital s y dos orbitales p para producir tres orbitales híbridos idénticos orientados en una geometría trigonal plana ().
Aunque la mecánica cuántica produce los lóbulos orbitales "regordetes", como se representa en la , a veces, para mayor claridad, estos orbitales se dibujan más finos y sin los lóbulos menores, como en la , para no ocultar otras características de una determinada ilustración. Utilizaremos estas representaciones "más finas" siempre que la vista real esté demasiado aglomerada para visualizarla fácilmente.
La estructura observada de la molécula de borano, BH3, sugiere una hibridación sp2 para el boro en este compuesto. La molécula es trigonal plana, y el átomo de boro participa en tres enlaces con átomos de hidrógeno (). Podemos ilustrar la comparación de los orbitales y la distribución de los electrones en un átomo de boro aislado y en el átomo enlazado en BH3 como se muestra en el diagrama de niveles de energía orbital en la . Redistribuimos los tres electrones de valencia del átomo de boro en los tres orbitales híbridos sp2, y cada electrón de boro se empareja con un electrón de hidrógeno cuando se forman los enlaces B-H.
Cualquier átomo central rodeado por tres regiones de densidad electrónica mostrará hibridación sp2. Esto incluye moléculas con un par solitario en el átomo central, como el ClNO (), o moléculas con dos enlaces simples y un doble enlace conectado al átomo central, como en el formaldehído, CH2O, y el eteno, H2CCH2.
### hibridación sp3
Los orbitales de valencia de un átomo rodeado por una disposición tetraédrica de pares de enlace y pares solitarios consisten en un conjunto de cuatro orbitales híbridos . Los híbridos son el resultado de la mezcla de un orbital s y los tres orbitales p que produce cuatro orbitales híbridos sp3 idénticos (). Cada uno de estos orbitales híbridos apunta hacia una esquina diferente del tetraedro.
Una molécula de metano, CH4, está formada por un átomo de carbono rodeado por cuatro átomos de hidrógeno en las esquinas de un tetraedro. El átomo de carbono del metano presenta hibridación sp3. En la ilustramos los orbitales y la distribución de electrones en un átomo de carbono aislado y en el átomo enlazado en CH4. Los cuatro electrones de valencia del átomo de carbono se distribuyen por igual en los orbitales híbridos, y cada electrón del carbono se empareja con un electrón de hidrógeno cuando se forman los enlaces C-H.
En una molécula de metano, el orbital 1s de cada uno de los cuatro átomos de hidrógeno se superpone con uno de los cuatro orbitales sp3 del átomo de carbono para formar un enlace sigma (σ). Esto da lugar a la formación de cuatro enlaces covalentes fuertes y equivalentes entre el átomo de carbono y cada uno de los átomos de hidrógeno para producir la molécula de metano, CH4.
La estructura del etano, C2H6, es similar a la del metano en el sentido de que cada carbono del etano tiene cuatro átomos vecinos dispuestos en las esquinas de un tetraedro: tres átomos de hidrógeno y uno de carbono (). Sin embargo, en el etano un orbital sp3 de un átomo de carbono se superpone de extremo a extremo con un orbital sp3 de un segundo átomo de carbono para formar un enlace σ entre los dos átomos de carbono. Cada uno de los orbitales híbridos sp3 restantes se superpone con un orbital s de un átomo de hidrógeno para formar enlaces σ carbono-hidrógeno. La estructura y el esquema general de los orbitales de enlace del etano se muestran en la . La orientación de los dos grupos CH3 no es fija entre sí. Las pruebas experimentales demuestran que la rotación alrededor de los enlaces σ se produce fácilmente.
Un orbital híbrido sp3 también puede albergar un par solitario de electrones. Por ejemplo, el átomo de nitrógeno del amoníaco está rodeado por tres pares de enlaces y un par solitario de electrones dirigidos a las cuatro esquinas de un tetraedro. El átomo de nitrógeno está hibridado sp3 con un orbital híbrido ocupado por el par solitario.
La estructura molecular del agua es consistente con una disposición tetraédrica de dos pares solitarios y dos pares de electrones de enlace. Así, decimos que el átomo de oxígeno está hibridado sp3, con dos de los orbitales híbridos ocupados por pares solitarios y dos por pares de enlace. Dado que los pares solitarios ocupan más espacio que los pares de enlace, las estructuras que contienen pares solitarios tienen ángulos de enlace ligeramente distorsionados con respecto al ideal. Los tetraedros perfectos tienen ángulos de 109,5°, pero los ángulos observados en el amoníaco (107,3°) y el agua (104,5°) son ligeramente menores. Otros ejemplos de hibridación sp3 son el CCl4, el PCl3 y el NCl3.
### Hibridación sp3d y sp3d2
Para describir los cinco orbitales de enlace en una disposición bipiramidal trigonal, debemos utilizar cinco de los orbitales atómicos de la capa de valencia (el orbital s, los tres orbitales p y uno de los orbitales d), lo que da cinco orbitales híbridos . Con una disposición octaédrica de seis orbitales híbridos, debemos utilizar seis orbitales atómicos de la capa de valencia (el orbital s, los tres orbitales p y dos de los orbitales d de su capa de valencia), lo que da seis orbitales híbridos . Estas hibridaciones solo son posibles para los átomos que tienen orbitales d en sus subcapas de valencia (es decir, no los del primer o segundo periodo).
En una molécula de pentacloruro de fósforo, PCl5, hay cinco enlaces P-Cl (por tanto, cinco pares de electrones de valencia alrededor del átomo de fósforo) dirigidos hacia las esquinas de una bipirámide trigonal. Utilizamos el orbital 3s, los tres orbitales 3p y uno de los orbitales 3d para formar el conjunto de cinco orbitales híbridos sp3d () que intervienen en los enlaces P-Cl. Otros átomos que presentan hibridación sp3d son el átomo de azufre en SF4 y los átomos de cloro en ClF3 y en (Los electrones de los átomos de flúor se omiten para mayor claridad).
El átomo de azufre del hexafluoruro de azufre, SF6, presenta hibridación sp3d2. Una molécula de hexafluoruro de azufre tiene seis pares de electrones de enlace que conectan seis átomos de flúor con un único átomo de azufre. No hay pares solitarios de electrones en el átomo central. Para enlazar seis átomos de flúor, el orbital 3s, los tres orbitales 3p y dos de los orbitales 3d forman seis orbitales híbridos sp3d2 equivalentes, cada uno dirigido hacia una esquina diferente de un octaedro. Otros átomos que presentan hibridación sp3d2 son el átomo de fósforo en el átomo de yodo en los interhalógenos IF5, y el átomo de xenón en XeF4
### Asignación de orbitales híbridos a los átomos centrales
La hibridación de un átomo se determina en función del número de regiones de densidad electrónica que lo rodean. Las disposiciones geométricas características de los distintos conjuntos de orbitales híbridos se muestran en la . Estas disposiciones son idénticas a las de las geometrías de pares de electrones predichas por la teoría VSEPR. La teoría VSEPR predice las formas de las moléculas, y la teoría de los orbitales híbridos ofrece una explicación de cómo se forman esas formas. Para hallar la hibridación de un átomo central, podemos utilizar las siguientes pautas:
1. Determinar la estructura de Lewis de la molécula.
2. Determinar el número de regiones de densidad electrónica alrededor de un átomo utilizando la teoría VSEPR, en la que los enlaces simples, los enlaces múltiples, los radicales y los pares solitarios cuentan cada uno como una región.
3. Asignar el conjunto de orbitales hibridados de la que corresponde a esta geometría.
Es importante recordar que la hibridación se ideó para racionalizar las geometrías moleculares observadas experimentalmente. El modelo funciona bien para las moléculas que contienen átomos centrales pequeños, en las que los pares de electrones de valencia están cerca en el espacio. Sin embargo, para los átomos centrales más grandes, los pares de electrones de la cáscara de valencia están más lejos del núcleo y hay menos repulsiones. Sus compuestos presentan estructuras que a menudo no son consistentes con la teoría VSEPR, y los orbitales hibridados no son necesarios para explicar los datos observados. Por ejemplo, hemos discutido el ángulo de enlace H-O-H en H2O, 104,5°, que es más consistente con los orbitales híbridos sp3 (109,5°) en el átomo central que con los orbitales 2p (90°). El azufre está en el mismo grupo que el oxígeno, y el H2S tiene una estructura de Lewis similar. Sin embargo, tiene un ángulo de enlace mucho menor (92,1°), lo que indica una hibridación mucho menor en el azufre que en el oxígeno. Siguiendo hacia abajo en el grupo, el telurio es incluso mayor que el azufre, y para el H2Te, el ángulo de enlace observado (90°) es consistente con la superposición de los orbitales 5p, sin invocar la hibridación. Invocamos la hibridación cuando es necesario para explicar las estructuras observadas.
### Conceptos clave y resumen
Podemos utilizar orbitales híbridos, que son combinaciones matemáticas de algunos o todos los orbitales atómicos de valencia, para describir la densidad electrónica alrededor de los átomos con enlaces covalentes. Estos orbitales híbridos forman enlaces sigma (σ) dirigidos hacia otros átomos de la molécula o contienen pares solitarios de electrones. Podemos determinar el tipo de hibridación alrededor de un átomo central a partir de la geometría de las regiones de densidad electrónica a su alrededor. Dos de esas regiones implican hibridación sp; tres, hibridación sp2; cuatro, hibridación sp3; cinco, hibridación sp3d; y seis, hibridación sp3d2. Los enlaces Pi (π) se forman a partir de orbitales atómicos no hibridados (orbitales p o d).
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# Teorías avanzadas del enlace covalente
## Enlaces múltiples
El modelo de orbitales híbridos parece explicar la geometría de las moléculas con enlaces covalentes simples. ¿Es capaz también de describir moléculas que contienen dobles y triples enlaces? Ya comentamos que los enlaces múltiples están formados por enlaces σ y π. A continuación consideraremos cómo visualizar estos componentes y cómo se relacionan con los orbitales híbridos. La estructura de Lewis del eteno, C2H4, nos muestra que cada átomo de carbono está rodeado por otro átomo de carbono y dos átomos de hidrógeno.
Las tres regiones de enlace forman una geometría trigonal plana de pares de electrones. Así, esperamos que los enlaces σ de cada átomo de carbono se formen utilizando un conjunto de orbitales híbridos sp2 que resultan de la hibridación de dos de los orbitales 2p y el orbital 2s (). Estos orbitales forman los enlaces simples C-H y el enlace σ en el doble enlace (). El enlace π en el doble enlace resulta de la superposición del tercer orbital 2p (restante) en cada átomo de carbono que no participa en la hibridación. Este orbital p no hibridado (lóbulos en rojo y azul en la ) es perpendicular al plano de los orbitales híbridos sp2. Así, los orbitales 2p no hibridados se superponen de forma lateral, por encima y por debajo del eje internuclear () y forman un enlace π.
En una molécula de eteno, los cuatro átomos de hidrógeno y los dos átomos de carbono están todos en el mismo plano. Si los dos planos de los orbitales híbridos sp2 estuvieran inclinados uno respecto al otro, los orbitales p no estarían orientados para superponerse eficazmente y crear el enlace π. La configuración planar de la molécula de eteno se produce porque es la disposición de enlace más estable. Esta es una diferencia significativa entre los enlaces σ y π; la rotación alrededor de los enlaces simples (σ) se produce fácilmente porque la superposición orbital de extremo a extremo no depende de la orientación relativa de los orbitales de cada átomo del enlace. En otras palabras, la rotación alrededor del eje internuclear no cambia el grado de superposición de los orbitales de enlace σ porque la densidad de electrones de enlace es simétrica respecto al eje. La rotación alrededor del eje internuclear es mucho más difícil para los enlaces múltiples; sin embargo, esto alteraría drásticamente la superposición fuera del eje de los orbitales de enlace π, rompiendo esencialmente el enlace π.
En las moléculas con orbitales híbridos sp, quedan dos orbitales p no hibridados en el átomo (). Esta situación la encontramos en el acetileno, que es una molécula lineal. Los orbitales híbridos sp de los dos átomos de carbono se superponen de extremo a extremo para formar un enlace σ entre los átomos de carbono (). Los orbitales sp restantes forman enlaces σ con átomos de hidrógeno. Los dos orbitales p no hibridados por carbono están colocados de tal manera que se superponen uno al lado del otro y, por tanto, forman dos enlaces π. Así, los dos átomos de carbono del acetileno están unidos por un enlace σ y dos enlaces π, dando lugar a un triple enlace.
En la hibridación solo intervienen los enlaces σ, los pares de electrones solitarios y los electrones simples no apareados (radicales). Las estructuras exhiben estas características describen la correcta hibridación de los átomos. Sin embargo, muchas estructuras también incluyen formas de resonancia. Recuerde que las formas de resonancia se producen cuando son posibles varias disposiciones de los enlaces π. Dado que la disposición de los enlaces π implica solo los orbitales no hibridados, la resonancia no influye en la asignación de la hibridación.
Por ejemplo, la molécula de benceno tiene dos formas de resonancia (). Podemos utilizar cualquiera de estas formas para determinar que cada uno de los átomos de carbono está unido a otros tres átomos sin pares solitarios, por lo que la hibridación correcta es sp2. Los electrones de los orbitales p no hibridados forman enlaces π. Ninguna de las dos estructuras de resonancia describe completamente los electrones de los enlaces π. No están localizados en una posición u otra, sino que en realidad están deslocalizados por todo el anillo. La teoría de enlace de valencia no aborda fácilmente la deslocalización. El enlace en las moléculas con formas de resonancia se describe mejor mediante la teoría de los orbitales moleculares (consulte el siguiente módulo).
### Conceptos clave y resumen
Los enlaces múltiples consisten en un enlace σ situado a lo largo del eje entre dos átomos y uno o dos enlaces π. Los enlaces σ suelen formarse por la superposición de orbitales atómicos hibridados, mientras que los enlaces π se forman por la superposición lateral de orbitales no hibridados. La resonancia se produce cuando hay múltiples orbitales no hibridados con la alineación adecuada para superponerse, por lo que la colocación de los enlaces π puede variar.
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# Teorías avanzadas del enlace covalente
## Teoría de los orbitales moleculares
En casi todas las moléculas covalentes que existen, ahora podemos dibujar la estructura de Lewis, predecir la geometría de pares de electrones así como la geometría molecular y acercarnos a la predicción de los ángulos de enlace. Sin embargo, una de las moléculas más importantes que conocemos, la molécula de oxígeno O2, presenta un problema con respecto a su estructura de Lewis. Escribiríamos la siguiente estructura de Lewis para el O2:
Esta estructura electrónica cumple todas las reglas de la teoría de Lewis. Hay un doble enlace O=O, y cada átomo de oxígeno tiene ocho electrones a su alrededor. Sin embargo, esta imagen no concuerda con el comportamiento magnético del oxígeno. Por sí mismo, el O2 no es magnético, pero lo atraen los campos magnéticos. Así, cuando vertemos oxígeno líquido frente a un imán fuerte, se acumula entre los polos del imán y desafía la gravedad, como en la . Esta atracción hacia un campo magnético se denomina paramagnetismo, y aparece en las moléculas que tienen electrones no apareados. Sin embargo, la estructura de Lewis del O2 indica que todos los electrones están emparejados. ¿Cómo se explica esta discrepancia?
La susceptibilidad magnética mide la fuerza experimentada por una sustancia en un campo magnético. Cuando comparamos el peso de una muestra con el peso medido en un campo magnético (), las muestras paramagnéticas atraídas por el imán parecerán más pesadas debido a la fuerza ejercida por el campo magnético. Podemos calcular el número de electrones no apareados en función del aumento de peso.
Los experimentos demuestran que cada molécula de O2 tiene dos electrones no apareados. El modelo de estructura de Lewis no predice la presencia de estos dos electrones no apareados. A diferencia del oxígeno, el peso aparente de la mayoría de las moléculas disminuye ligeramente en presencia de un campo magnético no homogéneo. Los materiales en los que todos los electrones están emparejados son diamagnéticos y repelen débilmente un campo magnético. Los materiales paramagnéticos y diamagnéticos no actúan como imanes permanentes. Solo en presencia de un campo magnético aplicado demuestran atracción o repulsión.
La teoría de los orbitales moleculares (molecular orbital theory, MO) ofrece una explicación del enlace químico que explica el paramagnetismo de la molécula de oxígeno. También explica el enlace en una serie de otras moléculas, como las violaciones de la regla del octeto y más moléculas con enlaces más complicados (más allá del alcance de este texto) que son difíciles de describir con estructuras de Lewis. Además, proporciona un modelo para describir las energías de los electrones en una molécula y la ubicación probable de estos. A diferencia de la teoría de enlace de valencia, que utiliza orbitales híbridos que se asignan a un átomo específico, la teoría MO utiliza la combinación de orbitales atómicos para producir orbitales moleculares que están deslocalizados en toda la molécula en lugar de estar localizados en sus átomos constituyentes. La teoría MO también nos ayuda a entender por qué algunas sustancias son conductoras de la electricidad, otras son semiconductoras y otras son aislantes. La resume los puntos principales de las dos teorías complementarias del enlace. Ambas teorías proporcionan formas diferentes y útiles de describir la estructura molecular.
La teoría de los orbitales moleculares describe la distribución de los electrones en las moléculas del mismo modo que la distribución de los electrones en los átomos se describe mediante los orbitales atómicos. Mediante la mecánica cuántica, el comportamiento de un electrón en una molécula se sigue describiendo a través de una función de onda, Ψ, análoga al comportamiento en un átomo. Al igual que los electrones alrededor de los átomos aislados, los electrones alrededor de los átomos en las moléculas están limitados a energías discretas (cuantizadas). La región del espacio en la que es probable que se encuentre un electrón de valencia en una molécula se llama orbital molecular (. Al igual que un orbital atómico, un orbital molecular está lleno cuando contiene dos electrones con espín opuesto.
Consideraremos los orbitales moleculares en moléculas compuestas por dos átomos idénticos (H2 o Cl2, por ejemplo). Estas moléculas se denominan moléculas diatómicas homonucleares. En estas moléculas diatómicas se dan varios tipos de orbitales moleculares.
El proceso matemático de combinación de orbitales atómicos para generar orbitales moleculares se denomina combinación lineal de orbitales atómicos (CLOA). La función de onda describe las propiedades ondulatorias de un electrón. Los orbitales moleculares son combinaciones de funciones de onda de orbitales atómicos. La combinación de ondas puede dar lugar a una interferencia constructiva, en la que los picos se alinean con las crestas, o a una interferencia destructiva, en la que los picos se alinean con las depresiones o valles (). En los orbitales, las ondas son tridimensionales y se combinan con las ondas en fase produciendo regiones con mayor probabilidad de densidad de electrones y con las ondas fuera de fase produciendo nodos o regiones sin densidad de electrones.
Hay dos tipos de orbitales moleculares que pueden formarse a partir de la superposición de dos orbitales atómicos s en átomos adyacentes. Los dos tipos se ilustran en la . La combinación en fase produce un orbital molecular de menor energía (se lee como "sigma-s") en el que la mayor parte de la densidad de electrones está directamente entre los núcleos. La adición fuera de fase (que también puede considerarse como una sustracción de las funciones de onda) produce una energía mayor (se lee como "sigma-s-asterisco") en la que hay un nodo entre los núcleos. El asterisco significa que el orbital es un orbital de antienlace. Los electrones en un orbital σ son atraídos por ambos núcleos al mismo tiempo y son más estables (de menor energía) de lo que serían en los átomos aislados. La adición de electrones a estos orbitales crea una fuerza que mantiene unidos los dos núcleos, por lo que llamamos a estos orbitales orbitales de enlace. Los electrones en los orbitales se encuentran bien alejados de la región entre los dos núcleos. La fuerza de atracción entre los núcleos y estos electrones separa los dos núcleos. Por lo tanto, estos orbitales se denominan orbitales de antienlace. Los electrones llenan el orbital de enlace de menor energía antes que el orbital de antienlace de mayor energía, al igual que llenan los orbitales atómicos de menor energía antes que los de mayor energía.
En los orbitales p, la función de onda da lugar a dos lóbulos con fases opuestas, de forma análoga a cuando una onda bidimensional tiene partes por encima y por debajo de la media. Indicamos las fases sombreando los lóbulos orbitales de diferentes colores. Cuando los lóbulos orbitales de la misma fase se superponen, la interferencia de onda constructiva aumenta la densidad de electrones. Cuando las regiones de fase opuesta se superponen, la interferencia de onda destructiva disminuye la densidad de electrones y crea nodos. Cuando los orbitales p se superponen de extremo a extremo, crean orbitales σ y σ* (). Si dos átomos están situados a lo largo del eje x en un sistema de coordenadas cartesianas, los dos orbitales p se superponen de extremo a extremo y forman σ (enlace) y (antienlace) (se lee como "sigma-p-x" y "asterisco sigma-p-x", respectivamente). Al igual que en el caso de la superposición de orbitales s, el asterisco indica el orbital con un nodo entre los núcleos, que es un orbital de antienlace de mayor energía.
La superposición lateral de dos orbitales p da lugar a un orbital molecular de enlace pi (π) y a un orbital molecular de antienlace π*, como se muestra en la . En la teoría de enlace de valencia, describimos los enlaces π como si contuvieran un plano nodal que contiene el eje internuclear y es perpendicular a los lóbulos de los orbitales p, con densidad electrónica a ambos lados del nodo. En la teoría del orbital molecular, describimos el orbital π con esta misma forma, y existe un enlace π cuando este orbital contiene electrones. Los electrones de este orbital interactúan con ambos núcleos y ayudan a mantener unidos a los dos átomos, lo que lo convierte en un orbital de enlace. En la combinación fuera de fase, se crean dos planos nodales, uno a lo largo del eje internuclear y otro perpendicular entre los núcleos.
En los orbitales moleculares de las moléculas diatómicas, cada átomo tiene también dos conjuntos de orbitales p orientados uno al lado del otro (p y p), por lo que estos cuatro orbitales atómicos se combinan por parejas para crear dos orbitales π y dos orbitales π*. Los valores π y están orientados en ángulo recto con respecto a los orbitales π y los orbitales . Excepto por su orientación, orbitales los π y π son idénticos y tienen la misma energía; son orbitales degenerados. Los orbitales de antienlace y también son degenerados e idénticos excepto por su orientación. Un total de seis orbitales moleculares resulta de la combinación de los seis orbitales p atómicos en dos átomos: σ y π y π y
### Diagramas de energía orbital molecular
Los niveles de energía relativos de los orbitales atómicos y moleculares se suelen mostrar en un diagrama de orbitales moleculares (). En una molécula diatómica, los orbitales atómicos de un átomo se muestran a la izquierda, y los del otro átomo a la derecha. Cada línea horizontal representa un orbital que puede contener dos electrones. Los orbitales moleculares formados por la combinación de los orbitales atómicos se muestran en el centro. Las líneas discontinuas muestran qué orbitales atómicos se combinan para formar los orbitales moleculares. Por cada par de orbitales atómicos que se combinan, resulta un orbital molecular de menor energía (de enlace) y un orbital de mayor energía (antienlace). Así podemos ver que la combinación de los seis orbitales atómicos 2p da como resultado tres orbitales de enlace (uno σ y dos π) y tres orbitales de antienlace (uno σ* y dos π*).
Predecimos la distribución de los electrones en estos orbitales moleculares llenando los orbitales de la misma manera que llenamos los orbitales atómicos, por el principio de Aufbau. Los orbitales de menor energía se llenan primero, los electrones se reparten entre los orbitales degenerados antes de emparejarse, y cada orbital puede contener un máximo de dos electrones con espines opuestos (). Al igual que escribimos las configuraciones electrónicas de los átomos, podemos escribir la configuración electrónica molecular enumerando los orbitales con superíndices que indican el número de electrones presentes. Para mayor claridad, colocamos paréntesis alrededor de los orbitales moleculares con la misma energía. En este caso, cada orbital tiene una energía diferente, por lo que los paréntesis separan cada orbital. Por lo tanto, esperaríamos que una molécula diatómica o un ion que contenga siete electrones (como tendría la configuración electrónica molecular Es habitual omitir los electrones del núcleo en los diagramas y configuraciones de orbitales moleculares e incluir solo los electrones de valencia.
### Orden de enlace
El diagrama de orbitales moleculares rellenos muestra el número de electrones en los orbitales moleculares de enlace y antienlace. La contribución neta de los electrones a la fuerza de enlace de una molécula se identifica determinando el orden de enlace que resulta del llenado de los orbitales moleculares por los electrones.
Al utilizar las estructuras de Lewis para describir la distribución de los electrones en las moléculas, definimos el orden de enlace como el número de pares de electrones de enlace entre dos átomos. Así, un enlace simple tiene un orden de enlace 1, un doble enlace tiene un orden de enlace 2 y un triple enlace tiene un orden de enlace 3. Definimos el orden de los enlaces de forma diferente cuando utilizamos la descripción del orbital molecular de la distribución de los electrones, pero el orden de los enlaces resultante suele ser el mismo. La técnica MO es más precisa y puede manejar casos en los que el método de la estructura de Lewis falla, pero ambos métodos describen el mismo fenómeno.
En el modelo de orbital molecular, un electrón contribuye a una interacción de enlace si ocupa un orbital de enlace y contribuye a una interacción de antienlace si ocupa un orbital de antienlace. El orden de los enlaces se calcula restando los electrones desestabilizadores (antienlace) de los estabilizadores (enlace). Como un enlace está formado por dos electrones, dividimos entre dos para obtener el orden del enlace. Podemos determinar el orden de los enlaces con la siguiente ecuación:
El orden de un enlace covalente es una guía para su fuerza; un enlace entre dos átomos dados se hace más fuerte a medida que el orden del enlace aumenta (). Si la distribución de electrones en los orbitales moleculares entre dos átomos es tal que el enlace resultante tendría un orden de enlace cero, no se forma un enlace estable. A continuación, veremos algunos ejemplos concretos de diagramas de MO y órdenes de enlace.
### El enlace en las moléculas diatómicas
Una molécula de dihidrógeno (H2) se forma a partir de dos átomos de hidrógeno. Cuando los orbitales atómicos de los dos átomos se combinan, los electrones ocupan el orbital molecular de menor energía, el orbital de enlace σ1. Una molécula de dihidrógeno, H2, se forma fácilmente porque la energía de una molécula de H2 es menor que la de dos átomos de H. El orbital σ1 que contiene ambos electrones es de menor energía que cualquiera de los dos orbitales atómicos 1s.
Un orbital molecular puede contener dos electrones, por lo que ambos electrones de la molécula de H2 están en el orbital de enlace σ1; la configuración electrónica es Representamos esta configuración mediante un diagrama de energía orbital molecular () en el que una sola flecha hacia arriba indica un electrón en un orbital, y dos flechas (hacia arriba y hacia abajo) indican dos electrones de espín opuesto.
Una molécula de dihidrógeno contiene dos electrones enlazantes y ningún electrón antienlazante, por lo que tenemos
Dado que el orden de enlace para el enlace H-H es igual a 1, el enlace es un enlace simple.
Un átomo de helio tiene dos electrones, ambos en su orbital 1s. Dos átomos de helio no se combinan para formar una molécula de dihelio, He2, con cuatro electrones, porque el efecto estabilizador de los dos electrones en el orbital de enlace de menor energía se vería compensado por el efecto desestabilizador de los dos electrones en el orbital molecular antienlace de mayor energía. Escribiríamos la configuración electrónica hipotética del He2 como como en la . El cambio de energía neto sería cero, por lo que no hay fuerza motriz para que los átomos de helio formen la molécula diatómica. De hecho, el helio existe como átomos discretos y no como moléculas diatómicas. El orden de los enlaces en una hipotética molécula de dihelio sería cero.
Un orden de enlace de cero indica que no se forma ningún enlace entre dos átomos.
### Las moléculas diatómicas del segundo periodo
Los átomos del segundo periodo de la tabla periódica podrían formar ocho posibles moléculas diatómicas homonucleares: Li2, Be2, B2, C2, N2, O2, F2, y Ne2. Sin embargo, podemos predecir que la molécula de Be2 y la de Ne2 no serían estables. Esto lo podemos ver considerando las configuraciones electrónicas moleculares ().
Predecimos las configuraciones electrónicas de los orbitales de valencia de las moléculas de la misma manera que las configuraciones electrónicas de los átomos. Los electrones de valencia se asignan a los orbitales moleculares de valencia con las energías más bajas posibles. De acuerdo con la regla de Hund, siempre que haya dos o más orbitales moleculares degenerados, los electrones llenan cada orbital de ese tipo de forma individual antes de que se produzca cualquier emparejamiento de electrones.
Como vimos en la teoría de enlace de valencia, los enlaces σ son generalmente más estables que los enlaces π formados a partir de orbitales atómicos degenerados. Del mismo modo, en la teoría de orbitales moleculares, los orbitales σ suelen ser más estables que los π. Sin embargo, no siempre es así. Los MO para los orbitales de valencia del segundo periodo se muestran en la . Observando los orbitales moleculares del Ne2, vemos que el orden es consistente con el diagrama genérico mostrado en la sección anterior. Sin embargo, para los átomos con tres o menos electrones en los orbitales p (del Li al N) observamos un patrón diferente, en el que el orbital σ es más alto en energía que el conjunto orbital π. Obtenga el diagrama de orbitales moleculares de un ion diatómico homonuclear añadiendo o restando electrones del diagrama de la molécula neutra.
Este cambio en el ordenamiento de los orbitales se produce debido a un fenómeno llamado mezcla s-p. La mezcla s-p no crea nuevos orbitales; simplemente influye en las energías de los orbitales moleculares existentes. La función de onda σs se combina matemáticamente con la función de onda σp, con el resultado de que el orbital σs se vuelve más estable, y el orbital σp se vuelve menos estable (). Del mismo modo, los orbitales de antienlace también sufren una mezcla s-p, con la σs* volviéndose más estable y la σp* volviéndose menos estable.
la mezcla s-p se produce cuando los orbitales s y p tienen energías similares. La diferencia de energía entre los orbitales 2s y 2p en el O, el F y el Ne es mayor que en el Li, el Be, el B, el C y el N. Debido a esto, el O2, el F2, y el Ne2 presentan una mezcla s-p insignificante (no suficiente para cambiar el ordenamiento energético), y sus diagramas de la MO siguen el patrón normal, como se muestra en la . Todas las demás moléculas diatómicas de periodo 2 sí tienen mezcla s-p, lo que lleva al patrón en el que el orbital σp se eleva por encima del conjunto πp.
Utilizando los diagramas de MO que se muestran en la , podemos añadir los electrones y determinar la configuración electrónica molecular y el orden de los enlaces en cada una de las moléculas diatómicas. Como se muestra en la , las moléculas de Be2 y Ne2 tendrían un orden de enlace de 0, y estas moléculas no existen.
La combinación de dos átomos de litio para formar una molécula de litio, Li2 es análoga a la formación de H2, pero los orbitales atómicos involucrados son los orbitales de valencia 2s. Cada uno de los dos átomos de litio tiene un electrón de valencia. Por lo tanto, tenemos dos electrones de valencia disponibles para el orbital molecular de enlace σ2. Como ambos electrones de valencia estarían en un orbital de enlace, predeciríamos que la molécula de Li2 es estable. De hecho, la molécula está presente en una concentración apreciable en el vapor de litio a temperaturas cercanas al punto de ebullición del elemento. También se conocen todas las demás moléculas de la con un orden de enlace superior a cero.
La molécula de O2 tiene suficientes electrones para llenar la mitad del nivel . Esperamos que los dos electrones que ocupan estos dos orbitales degenerados no estén apareados, y esta configuración electrónica molecular del el O2 está de acuerdo con el hecho de que la molécula de oxígeno tiene dos electrones no apareados (). La presencia de dos electrones no apareados ha resultado difícil de explicar mediante las estructuras de Lewis, pero la teoría de los orbitales moleculares lo explica bastante bien. De hecho, los electrones no apareados de la molécula de oxígeno proporcionan un fuerte apoyo a la teoría del orbital molecular.
### Conceptos clave y resumen
La teoría de los orbitales moleculares (MO) describe el comportamiento de los electrones en una molécula en términos de combinaciones de las funciones de onda atómicas. Los orbitales moleculares resultantes pueden extenderse por todos los átomos de la molécula. Los orbitales moleculares de enlace están formados por combinaciones en fase de las funciones de onda atómicas, y los electrones de estos orbitales estabilizan una molécula. Los orbitales moleculares antienlazantes son el resultado de combinaciones fuera de fase de las funciones de onda atómicas y los electrones en estos orbitales hacen que una molécula sea menos estable. Los orbitales moleculares situados a lo largo de un eje internuclear se denominan σ MOs. Pueden formarse a partir de orbitales s o de orbitales p orientados de extremo a extremo. Los orbitales moleculares formados a partir de orbitales p orientados de forma lateral tienen la densidad de electrones en lados opuestos del eje internuclear y se denominan orbitales π.
Podemos describir la estructura electrónica de las moléculas diatómicas aplicando la teoría de los orbitales moleculares a los electrones de valencia de los átomos. Los electrones llenan los orbitales moleculares siguiendo las mismas reglas que se aplican para llenar los orbitales atómicos; la regla de Hund y el principio de Aufbau nos dicen que los orbitales de menor energía se llenarán primero, los electrones se dispersarán antes de emparejarse y cada orbital puede contener un máximo de dos electrones con espines opuestos. Los materiales con electrones no apareados son paramagnéticos y son atraídos por un campo magnético, mientras que los que tienen todos los electrones apareados son diamagnéticos y son repelidos por un campo magnético. La predicción correcta de las propiedades magnéticas de las moléculas es una ventaja de la teoría de los orbitales moleculares sobre las estructuras de Lewis y la teoría de enlace de valencia.
### Ecuaciones clave
### Ejercicios de fin de capítulo de Química
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# Gases
## Introducción
Estamos rodeados de un océano de gas —la atmósfera— y muchas de las propiedades de los gases nos resultan familiares por nuestras actividades diarias. Los gases calentados se expanden, lo que puede hacer que un globo de aire caliente se eleve () o provocar un reventón en un neumático de bicicleta dejado al sol en un día caluroso.
Los gases han desempeñado un papel importante en el desarrollo de la química. En los siglos XVII y XVIII, muchos científicos investigaron el comportamiento de los gases, proporcionando las primeras descripciones matemáticas del comportamiento de la materia.
En este capítulo, examinaremos las relaciones entre la temperatura, la presión, la cantidad y el volumen de los gases. Estudiaremos un modelo teórico sencillo y lo utilizaremos para analizar el comportamiento experimental de los gases. Los resultados de estos análisis nos mostrarán las limitaciones de la teoría y cómo mejorarla. |
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