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L_0751 | electromagnetic waves | T_3798 | FIGURE 21.3 A photon of light energy is given off when an electron returns to a lower energy level. | image | textbook_images/electromagnetic_waves_22424.png |
L_0752 | properties of electromagnetic waves | T_3800 | FIGURE 21.4 Light slows down when it enters water from the air. This causes the wave to refract, or bend. | image | textbook_images/properties_of_electromagnetic_waves_22425.png |
L_0752 | properties of electromagnetic waves | T_3802 | FIGURE 21.5 Wavelength and frequency of electromagnetic waves. | image | textbook_images/properties_of_electromagnetic_waves_22426.png |
L_0753 | the electromagnetic spectrum | T_3804 | FIGURE 21.6 Electromagnetic radiation from the sun reaches Earth across space. It strikes everything on Earths surface, including these volleyball players. | image | textbook_images/the_electromagnetic_spectrum_22427.png |
L_0753 | the electromagnetic spectrum | T_3804 | FIGURE 21.7 How do the wavelength and frequency of waves change across the electromagnetic spectrum? | image | textbook_images/the_electromagnetic_spectrum_22428.png |
L_0753 | the electromagnetic spectrum | T_3806 | FIGURE 21.8 AM radio waves reflect off the ionosphere and travel back to Earth. Radio waves used for FM radio and television pass through the ionosphere and do not reflect back. | image | textbook_images/the_electromagnetic_spectrum_22429.png |
L_0753 | the electromagnetic spectrum | T_3807 | FIGURE 21.9 This television tower broadcasts signals using radio waves. | image | textbook_images/the_electromagnetic_spectrum_22430.png |
L_0753 | the electromagnetic spectrum | T_3810 | FIGURE 21.10 Microwaves are used for cell phones and radar. MEDIA Click image to the left or use the URL below. URL: https://www.ck12.org/flx/render/embeddedobject/5050 | image | textbook_images/the_electromagnetic_spectrum_22431.png |
L_0753 | the electromagnetic spectrum | T_3810 | FIGURE 21.11 Red light (right) has the longest wave- length, and violet light (left) has the short- est wavelength. | image | textbook_images/the_electromagnetic_spectrum_22432.png |
L_0753 | the electromagnetic spectrum | T_3812 | FIGURE 21.12 This sterilizer for laboratory equipment uses ultraviolet light to kill bacteria. | image | textbook_images/the_electromagnetic_spectrum_22433.png |
L_0753 | the electromagnetic spectrum | T_3813 | FIGURE 21.13 If your skin normally burns in 10 minutes of sun exposure, using sunscreen with an SPF of 30 means that, ideally, your skin will burn only after 30 times 10 minutes, or 300 minutes, of sun exposure. How long does sunscreen with an SPF of 50 protect skin from sunburn? | image | textbook_images/the_electromagnetic_spectrum_22434.png |
L_0753 | the electromagnetic spectrum | T_3814 | FIGURE 21.14 Two common uses of X rays are illustrated here. | image | textbook_images/the_electromagnetic_spectrum_22435.png |
L_0753 | the electromagnetic spectrum | DD_0216 | This diagram shows light waves of varying lengths, and some of their characteristics. The red line illustrates the wavelengths. Above that is a bar showing which light waves penetrate the Earth's atmosphere. Below the red line are the names of the different types of light, with their wavelength measured in (m). The illustrations of physical objects are to show scale. Below that is a diagram of the different light frequencies, measured in Hertz. Below that is a measure of the temperatures at which these light waves are most commonly emitted. | image | teaching_images/em_spectrum_6818.png |
L_0753 | the electromagnetic spectrum | DD_0217 | The diagram shows different kinds of waves. Visible light is the part of the electromagnetic spectrum that humans can see. Visible light includes all the colors of the rainbow. Each color is determined by its wavelength. Visible light ranges from violet wavelengths of 400 nanometers (nm) through red at 700 nm. There are parts of the electromagnetic spectrum that humans cannot see. This radiation exists all around you. You just cant see it! Every star, including our Sun, emits radiation of many wavelengths. Astronomers can learn a lot from studying the details of the spectrum of radiation from a star. Many extremely interesting objects cant be seen with the unaided eye. | image | teaching_images/em_spectrum_9095.png |
L_0754 | the light we see | T_3817 | FIGURE 22.1 This classroom has two obvious sources of visible light. Can you identify all of them? | image | textbook_images/the_light_we_see_22436.png |
L_0754 | the light we see | T_3818 | FIGURE 22.2 Bioluminescent organisms include jelly- fish and fireflies. Jellyfish give off visible light to startle predators. Fireflies give off visible light to attract mates. | image | textbook_images/the_light_we_see_22437.png |
L_0754 | the light we see | T_3825 | FIGURE 22.3 The objects pictured here differ in the way light interacts with them. | image | textbook_images/the_light_we_see_22438.png |
L_0754 | the light we see | T_3826 | FIGURE 22.4 The color of light depends on its wave- length. | image | textbook_images/the_light_we_see_22439.png |
L_0754 | the light we see | T_3826 | FIGURE 22.5 A prism separates visible light into its different wavelengths. | image | textbook_images/the_light_we_see_22440.png |
L_0754 | the light we see | T_3826 | FIGURE 22.6 The color that objects appear depends on the wavelengths of light they reflect or transmit. | image | textbook_images/the_light_we_see_22441.png |
L_0754 | the light we see | T_3826 | FIGURE 22.7 The three primary colors of lightred, green, and bluecombine to form white light in the center of the figure. What are the secondary colors of light? Can you find them in the diagram? | image | textbook_images/the_light_we_see_22442.png |
L_0754 | the light we see | T_3827 | FIGURE 22.8 Printer ink comes in three primary pig- ment colors: cyan, magenta, and yellow. | image | textbook_images/the_light_we_see_22443.png |
L_0755 | optics | T_3829 | FIGURE 22.9 Still waters of a lake create a mirror image of the surrounding scenery. | image | textbook_images/optics_22444.png |
L_0755 | optics | T_3830 | FIGURE 22.10 Whether reflection is regular or diffuse de- pends on the smoothness of the reflective surface. | image | textbook_images/optics_22445.png |
L_0755 | optics | T_3831 | FIGURE 22.11 According to the law of reflection, the an- gle of reflection always equals the angle of incidence. The angles of both reflected and incident light are measured relative to an imaginary line, called normal, that is perpendicular (at right angles) to the reflective surface. | image | textbook_images/optics_22446.png |
L_0755 | optics | T_3834 | FIGURE 22.12 The term mirror image refers to how left and right are reversed in the image compared with the real object. | image | textbook_images/optics_22447.png |
L_0755 | optics | T_3834 | FIGURE 22.13 The image created by a concave mirror depends on how far the object is from the mirror. | image | textbook_images/optics_22448.png |
L_0755 | optics | T_3836 | FIGURE 22.14 A convex mirror forms a virtual image that appears to be on the opposite side of the mirror from the object. How is the image different from the object? | image | textbook_images/optics_22449.png |
L_0755 | optics | T_3836 | FIGURE 22.15 Light refracts when it passes from one medium to another at an angle other than 90 . Can you explain why? | image | textbook_images/optics_22450.png |
L_0755 | optics | T_3838 | FIGURE 22.16 The image formed by a concave lens is a virtual image. | image | textbook_images/optics_22451.png |
L_0755 | optics | T_3841 | FIGURE 22.17 The type of image made by a convex lens depends on how close the object is to the lens. Which diagram shows how a hand lens makes an image? | image | textbook_images/optics_22452.png |
L_0755 | optics | T_3841 | FIGURE 22.18 A compound microscope uses convex lenses to make enlarged images of tiny objects. | image | textbook_images/optics_22453.png |
L_0755 | optics | T_3843 | FIGURE 22.19 These telescopes differ in how they collect light, but both use convex lenses to enlarge the image. | image | textbook_images/optics_22454.png |
L_0755 | optics | T_3843 | FIGURE 22.20 A camera uses a convex lens to form an image on film or a sensor. | image | textbook_images/optics_22455.png |
L_0755 | optics | T_3844 | FIGURE 22.21 A very focused beam of bright laser light moves around the room for the cat to chase. The diagram shows why the beam of laser light is so focused compared with ordinary light from a flashlight. | image | textbook_images/optics_22456.png |
L_0755 | optics | T_3844 | FIGURE 22.22 A laser light uses two concave mirrors to focus photons of colored light. | image | textbook_images/optics_22457.png |
L_0755 | optics | DD_0218 | This diagram explains the concept of refraction. Light travels at a constant speed in vaccuum but travels at different speends in different media. When light travels from one medium to another, the speed of light changes causing it to appear to bend. This bending of light is called refraction. Refraction occurs when the angle of incidence (i) is not 90 degrees. In this diagram (r) is the angle of refraction. The angle of refraction is dependent on the angle o incidence as well as the speed of light in the medium through which it is travelling. XY is the boundary between the media through which light is travelling. At the point of incidence where the ray strikes the boundary XY, a line can be drawn perpendicular to XY. This line is known as a normal line (labeled NN' in the diagram) . | image | teaching_images/optics_refraction_9190.png |
L_0755 | optics | DD_0219 | This diagram shows the setup of an amateur reflecting telescope. The telescope tube sits on a movable mount that allows it to point at and track objects in the sky. The mount shown is equitorial, meaning that it can be aligned to the north star for easier tracking of other stars and planets as they move accross the sky. The mount has a counterweight to help balance the wieght of the telescope tube. The entire assembly sits on the three legs of a tripod. When pointed at the sky, light enters the optical tube through it's aperture. The aperture is the circular end of the tube that allows light to enter when uncovered. Once light has entered the telescope, it is gathered and directed to the eyepiece by mirrors. The lenses in the eyepeice take this light and bring an image to focus for a human to see. The finderscope is a second smaller telescope attached the optical tube. It has lower magnification than the telescope, and this makes finding onjects and pointing the telescope easier. | image | teaching_images/parts_telescope_8149.png |
L_0755 | optics | DD_0220 | This diagram explains the law of reflection and shows how light gets reflected from a surface. The law of reflection states that the angle of incidence (i) is always equal to the angle of reflection (r). The angles of both reflected and incident ray are measured relative to the imaginary dotted-line, called normal, that is perpendicular (at right angles) to the mirror (reflective surface). On the other hand, Refraction is caused by the change in speed experienced by a wave when it changes medium. The refracted ray is a ray (drawn perpendicular to the wave fronts) that shows the direction that light travels after it has crossed over the boundary. The angle that the incident ray makes with the normal line is referred to as the angle of incidence. Similarly, the angle that the refracted ray makes with the normal line is referred to as the angle of refraction. Thus, this is what the following diagram is all about. | image | teaching_images/optics_refraction_9200.png |
L_0755 | optics | DD_0221 | The diagram below is about two different types of lens. A lens is a transparent piece of glass or plastic with at least one curved surface. A lens works by refraction: it bends light rays as they pass through it so they change direction. In a convex lens (sometimes called a positive lens), the glass (or plastic) surfaces bulge outwards in the center giving the classic lentil-like shape. A convex lens is also called a converging lens because it makes parallel light rays passing through it bend inward and meet (converge) at a spot just beyond the lens known as the focal point Convex lenses are used in things like telescopes and binoculars to bring distant light rays to a focus in your eyes. A concave lens is exactly the opposite with the outer surfaces curving inward, so it makes parallel light rays curve outward or diverge. That's why concave lenses are sometimes called diverging lenses. (One easy way to remember the difference between concave and convex lenses is to think of concave lenses caving inwards). Concave lenses are used in things like TV projectors to make light rays spread out into the distance. | image | teaching_images/optics_lense_types_9163.png |
L_0755 | optics | DD_0222 | This diagram shows the arrangement of optics found in a refracting telescope. Llight entering the telescope first encounters the large objective lens placed a the telescopes aperure the optical tube through it's aperture, a circular opening at the forward end of the tube. The objective lens is convex, and it causes rays of light entered the telescope parallel to one another to converge. The eyepiece lens is located in the path of these converging rays, and brings an image to focus for the human eye. | image | teaching_images/parts_telescope_8156.png |
L_0755 | optics | DD_0223 | This Diagrams shows the different types of lenses. A lens is a clear (transparent) object (like glass, plastic or even a drop of water) that changes the way things look by bending the light that goes through it. They may make things appear larger, smaller, or upside-down. Lenses are classified by the curvature of the two optical surfaces. A lens is biconvex (or double convex, or just convex) if both surfaces are convex. If both surfaces have the same radius of curvature, the lens is equiconvex. A lens with two concave surfaces is biconcave (or just concave). If one of the surfaces is flat, the lens is plano-convex or plano-concave depending on the curvature of the other surface. A lens with one convex and one concave side is convex-concave or meniscus. It is this type of lens that is most commonly used in corrective lenses. If the lens is biconvex or plano-convex, a collimated beam of light passing through the lens converges to a spot (a focus) behind the lens. In this case, the lens is called a positive or converging lens. | image | teaching_images/optics_lense_types_9159.png |
L_0755 | optics | DD_0224 | This diagram shows the arrangement of optics found in a reflecting telescope. Light enters the optical tube through it's aperture, a circular opening at the forward end of the tube. When light enters the telescope, it encounters a concave reflecting mirror at the back of telescope tube. This large reflecting mirror is called the objective. Light reflected from the objective converges on a small right angle mirror at the center of the optical tube. This mirror reflects the gathered light to the eyepiece. The lenses in the eyepeice take this light and bring an image to focus for a human to see. | image | teaching_images/parts_telescope_8153.png |
L_0756 | vision | T_3845 | FIGURE 22.24 The human eye is the organ specialized to collect light and focus images. Structures of the Eye | image | textbook_images/vision_22459.png |
L_0756 | vision | T_3846 | FIGURE 22.25 The brain and eyes work together to allow us to see. | image | textbook_images/vision_22460.png |
L_0756 | vision | T_3847 | FIGURE 22.26 Myopia and hyperopia can be corrected with lenses. | image | textbook_images/vision_22461.png |
L_0761 | magnets and magnetism | T_3883 | FIGURE 24.2 The north and south poles of a bar magnet attract paper clips. | image | textbook_images/magnets_and_magnetism_22485.png |
L_0761 | magnets and magnetism | T_3886 | FIGURE 24.3 Lines of magnetic force are revealed by the iron filings attracted to this magnet. | image | textbook_images/magnets_and_magnetism_22486.png |
L_0761 | magnets and magnetism | T_3887 | FIGURE 24.4 When it come to magnets, there is a force of attraction between opposite poles and a force of repulsion between like poles. | image | textbook_images/magnets_and_magnetism_22487.png |
L_0761 | magnets and magnetism | T_3887 | FIGURE 24.5 Refrigerator magnets stick to a refrigerator door because it contains iron. Why wont the magnets stick to wooden cabinet doors? | image | textbook_images/magnets_and_magnetism_22488.png |
L_0761 | magnets and magnetism | T_3888 | FIGURE 24.6 Magnetic domains must be aligned by an outside magnetic field for most ferromagnetic materials to become magnets. | image | textbook_images/magnets_and_magnetism_22489.png |
L_0761 | magnets and magnetism | T_3889 | FIGURE 24.7 Paper clips become temporary magnets when placed in a magnetic field. An iron nail becomes a permanent magnet when stroked with a bar magnet. Some materials are natural permanent magnets. The most magnetic material in nature is the mineral magnetite, also called lodestone. The magnetic domains of magnetite naturally align with Earths axis. Figure 24.8 shows a chunk of magnetite attracting iron nails and iron filings. The magnetic properties of magnetite have been recognized for thousands of years. The earliest compasses used magnetite pointers to show direction. The magnetite spoon compass in Figure 24.8 dates back about 2000 years and comes from China. | image | textbook_images/magnets_and_magnetism_22490.png |
L_0761 | magnets and magnetism | T_3889 | FIGURE 24.8 Magnetite naturally attracts iron nails and filings. Its natural magnetism was discovered thousands of years ago. | image | textbook_images/magnets_and_magnetism_22491.png |
L_0762 | earth as a magnet | T_3890 | FIGURE 24.10 Earth is like a giant bar magnet. | image | textbook_images/earth_as_a_magnet_22493.png |
L_0762 | earth as a magnet | T_3892 | FIGURE 24.11 Earths magnetic north pole is close to the geographic north pole. | image | textbook_images/earth_as_a_magnet_22494.png |
L_0762 | earth as a magnet | T_3892 | FIGURE 24.12 The magnetosphere extends outward from Earth in all directions. | image | textbook_images/earth_as_a_magnet_22495.png |
L_0762 | earth as a magnet | T_3893 | FIGURE 24.13 We think of todays magnetic pole orientation as "normal" only because thats what we are used to. | image | textbook_images/earth_as_a_magnet_22496.png |
L_0762 | earth as a magnet | T_3894 | FIGURE 24.14 The alignment of magnetic domains in rocks on the ocean floor provide evidence for Earths magnetic reversals. | image | textbook_images/earth_as_a_magnet_22497.png |
L_0762 | earth as a magnet | T_3894 | FIGURE 24.15 Charged particles flow through Earths liquid outer core, making Earth a giant magnet. | image | textbook_images/earth_as_a_magnet_22498.png |
L_0762 | earth as a magnet | T_3895 | FIGURE 24.16 The garden warbler flies from Europe to central Africa in the fall and returns to Eu- rope in the spring. Its internal "compass" helps it find the way. | image | textbook_images/earth_as_a_magnet_22499.png |
L_0762 | earth as a magnet | DD_0230 | This Diagram shows the Earth's Magnetic Field. Our planetó»s magnetic field is believed to be generated deep down in the Earthó»s core. And is created by the rotation of the Earth and Earth's core. It shields the Earth against harmful particles in space. The field is unstable and has changed often in the history of the Earth. The magnetic field creates magnetic poles that are near the geographical poles. A compass uses the geomagnetic field to find directions. Many migratory animals also use the field when they travel long distances each spring and fall. The magnetic poles will trade places during a magnetic reversal. | image | teaching_images/earth_magnetic_field_6775.png |
L_0762 | earth as a magnet | DD_0231 | This Diagram Shows the earth and how it acts as a magnet. It clearly depicts the geographic north pole and the magnetic north pole. Like all magnets, Earth has a magnetic field. Earths magnetic field is called the magnetosphere. It is a huge region that extends outward from Earth for several thousand kilometers but is strongest at the poles. Evidence in rocks shows that Earths magnetic poles switched positions hundreds of times in the past. Scien- tists think that Earths magnetic field is caused by the movement of charged particles through molten metals in the outer core. Earths magnetic field helps protect Earths surface and its organisms from harmful solar particles by pulling most of the particles toward the magnetic poles. Earths magnetic field is also used for navigation by humans and many other | image | teaching_images/earth_magnetic_field_6788.png |
L_0767 | types of matter | T_3921 | FIGURE 3.7 Each of the elements described here has different uses because of its properties. | image | textbook_images/types_of_matter_22521.png |
L_0767 | types of matter | T_3924 | FIGURE 3.8 Gold is gold no matter where it is found because all gold atoms are alike. | image | textbook_images/types_of_matter_22522.png |
L_0767 | types of matter | T_3926 | FIGURE 3.9 Table salt is much different than its com- ponents. What are some of its proper- ties? | image | textbook_images/types_of_matter_22523.png |
L_0767 | types of matter | T_3927 | FIGURE 3.10 Water is a compound that forms molecules. Each water molecule consists of two atoms of hydrogen (white) and one atom of oxygen (red). | image | textbook_images/types_of_matter_22524.png |
L_0767 | types of matter | T_3927 | FIGURE 3.11 A crystal of table salt has a regular, repeating pattern of ions. | image | textbook_images/types_of_matter_22525.png |
L_0767 | types of matter | T_3928 | FIGURE 3.12 All these substances are mixtures. How do they differ from compounds? | image | textbook_images/types_of_matter_22526.png |
L_0767 | types of matter | T_3930 | FIGURE 3.13 These three mixtures differ in the size of their particles. Which mixture has the largest particles? Which has the smallest particles? | image | textbook_images/types_of_matter_22527.png |
L_0767 | types of matter | T_3931 | FIGURE 3.14 Separating the components of a mixture depends on their physical properties. Which physical property is used in each example shown here? | image | textbook_images/types_of_matter_22528.png |
L_0772 | inside the atom | T_3963 | FIGURE 5.1 This simple atomic model shows the par- ticles inside the atom. | image | textbook_images/inside_the_atom_22558.png |
L_0772 | inside the atom | T_3967 | FIGURE 5.2 This model shows the particles that make up a carbon atom. | image | textbook_images/inside_the_atom_22559.png |
L_0772 | inside the atom | T_3968 | FIGURE 5.3 The strong force is effective only between particles that are very close together in the nucleus. | image | textbook_images/inside_the_atom_22560.png |
L_0772 | inside the atom | T_3969 | FIGURE 5.4 The symbol He stands for the element helium. Can you infer how many electrons a helium atom has? | image | textbook_images/inside_the_atom_22561.png |
L_0772 | inside the atom | T_3971 | FIGURE 5.5 When a fluorine atom gains an electron, it becomes a negative fluoride ion. | image | textbook_images/inside_the_atom_22562.png |
L_0772 | inside the atom | T_3974 | FIGURE 5.6 All isotopes of a given element have the same number of protons (P), but they differ in the number of neutrons (N). What is the mass number of each isotope shown here? | image | textbook_images/inside_the_atom_22563.png |
L_0772 | inside the atom | DD_0241 | This diagram shows the makings of an atom. The nucleus contains protons and neutrons, which are represented as green and orange spheres. Protons have positive charges and neutrons have no charge. The rings outside the nucleus contain electrons, which have negative charges. The electrons are represented by purple spheres. The atom's mass is made up of the protons and neutrons. The outermost ring of electrons is called the valence ring, which contains one valence electron in this diagram. | image | teaching_images/atomic_structure_9020.png |
L_0772 | inside the atom | DD_0242 | Carbon has three isotopes which are shown in this diagram. Carbon always has six protons, but the number of neutrons it has can vary. The number of positivley charged protons in an isotope is called the atomic number. The mass number of an isotope is equal to the number of its positively charged protons plus the number its of neutrally charged neutrons. A Carbon-12 atom has six proton and six neutrons in its nucleus. A Carbon-13 isotope has six protons and seven neutron in its nucleus, giving it a mass number of thirteen. Tritium has a proton and two neutrons in its nucleus, giving it a mass number of three. All three have a single electron. Another isotope of carbon, Carbon-14 has six protons and eight neutron in its nucleus, giving it a mass number of fourteen. | image | teaching_images/isotopes_9127.png |
L_0772 | inside the atom | DD_0243 | Three isotopes of hydrogen are shown here. The number of protons in an atom determines the element, but the number of neutrons the atom of an element has can vary. The number of positivley charged protons in an isotope is called the atomic number. This will also equal the number of electrons in a neutrally charged atom. The mass number of an isotope is equal to it's atomic number plus the number of neutrally charged neutrons it has. A hydrogen atom has one proton and zero neutrons in its nucleus. Hyrogen has two isotopes called deuterium and tritium. Deuterim has a proton and a neutron in its nucleus, giving it a mass number of two. Tritium has a proton and two neutrons in its nucleus, giving it a mass number of three. All three have a single electron. | image | teaching_images/isotopes_7057.png |
L_0772 | inside the atom | DD_0244 | The figure shows the nuclear symbol for the chemical element Boron. There are two important numbers in a nuclear symbol. In the lower left part, there is the atomic number. The atomic number shows the number of protons. In the upper left part, there is the mass number. The mass number is the sum of the number of protons and neutrons. In addition, if the element is a ion, the charge is shown in the upper right part of the symbol. | image | teaching_images/atomic_mass_number_9001.png |
L_0772 | inside the atom | DD_0245 | The diagram shows how elements are written in relation to the mass and atomic number. The symbol X stands for the chemical symbol of the element. Two numbers are commonly used to distinguish atoms: atomic number and mass number. The symbol A at the top right of the element symbol refers to the mass number. Mass number is the number of protons plus the number of neutrons in an atom. The symbol Z at the bottom right of the element symbol refers to the atomic number. The atomic number is the number of protons in an atom. This number is unique for atoms of each kind of element. | image | teaching_images/atomic_mass_number_9009.png |
L_0772 | inside the atom | DD_0246 | The figure shows a diagrammatic representation of a Helium-4 atom. We see how the atom has a nucleus surrounded by shells of electrons. In this case, the atom has two protons and two neutrons in the central nucleus. Two electrons orbit around the nucleus. The electrons are both in the first shell. The protons have a positive charge. The electrons have a negative charge. The neutrons do not have a charge. | image | teaching_images/atomic_mass_number_9006.png |
L_0772 | inside the atom | DD_0247 | This diagram shows a simple model of an atom. At the center of the atom is the nucleus. The nucleus contains neutrons and protons. A proton is a particle with a positive electric charge. The neutron is a particle with no electric charge. Electrons are particles with negative charges. They revolve around the nucleus in orbits. An atom typically has the same number of protons and electrons. Hence the positive and negative charges cancel each other out. | image | teaching_images/atomic_structure_6540.png |
L_0772 | inside the atom | atomic_structure_9018 | This image shows the electron shells of a Germanium atom. There are a total of 32 orbiting electrons in four distinct shells. The inner shell has two electrons. The second shell has 8 electrons. The third shell has 18 electrons. The fourth, outer shell has 4 electrons. The electrons in the outer shell are called valence electrons. In the center of the atom sits the nucleus. The nucleus has a positive charge. | image | teaching_images/atomic_structure_9018.png |
L_0773 | history of the atom | T_3979 | FIGURE 5.7 Democritus first introduced the idea of the atom almost 2500 years ago. the idea of atoms was ridiculous. Unfortunately, Aristotles ideas were accepted for more than 2000 years. During that time, Democrituss ideas were more or less forgotten. | image | textbook_images/history_of_the_atom_22564.png |
L_0773 | history of the atom | T_3980 | FIGURE 5.8 John Dalton used evidence from experiments to show that atoms exist. | image | textbook_images/history_of_the_atom_22565.png |
L_0773 | history of the atom | T_3983 | FIGURE 5.9 Daltons model atoms were hard, solid balls. How do they differ from the atomic models you saw in the lesson "Inside the Atom" from earlier in the chapter? | image | textbook_images/history_of_the_atom_22566.png |
L_0773 | history of the atom | T_3985 | FIGURE 5.10 This sketch shows the basic set up of Thomsons experiments. The vacuum tube is a glass tube that contains very little air. It has metal plates at each end and along the sides. | image | textbook_images/history_of_the_atom_22567.png |
L_0773 | history of the atom | T_3987 | FIGURE 5.11 Thomsons atomic model includes neg- ative electrons in a "sea" of positive charge. | image | textbook_images/history_of_the_atom_22568.png |
L_0773 | history of the atom | T_3990 | FIGURE 5.12 Rutherford shot a beam of positive alpha particles at thin gold foil. | image | textbook_images/history_of_the_atom_22569.png |
L_0773 | history of the atom | T_3990 | FIGURE 5.13 This model shows Rutherfords idea of the atom. How does it compare with Thomsons plum pudding model? | image | textbook_images/history_of_the_atom_22570.png |
L_0774 | modern atomic theory | T_3992 | FIGURE 5.14 In Bohrs atomic model, electrons orbit at fixed distances from the nucleus. These distances are called energy levels. | image | textbook_images/modern_atomic_theory_22571.png |
L_0774 | modern atomic theory | T_3992 | FIGURE 5.15 This model of an atom contains six energy levels (n = 1 to 6). Atoms absorb or emit energy when some of their electrons jump to a different energy level. | image | textbook_images/modern_atomic_theory_22572.png |
L_0774 | modern atomic theory | T_3993 | FIGURE 5.16 Atoms in fireworks give off light when their electrons jump back to a lower energy level. | image | textbook_images/modern_atomic_theory_22573.png |
L_0774 | modern atomic theory | T_3996 | FIGURE 5.17 This sketch represents the electron cloud model for helium. What does the electron cloud represent? | image | textbook_images/modern_atomic_theory_22574.png |
L_0774 | modern atomic theory | T_3996 | FIGURE 5.18 This model represents an atom of the element magnesium (Mg). How many electrons does the atom have at each en- ergy level? What is the maximum number it could have at each level? | image | textbook_images/modern_atomic_theory_22575.png |
L_0775 | how elements are organized | T_3998 | FIGURE 6.2 Mendeleevs table of the elements organizes the elements by atomic mass. The table has a repeating pattern. | image | textbook_images/how_elements_are_organized_22577.png |
L_0775 | how elements are organized | T_4003 | FIGURE 6.3 The modern periodic table of the elements is a lot like Mendeleevs table. But the modern table is based on atomic number instead of atomic mass. It also has more than 110 elements. Mendeleevs table only had about 65 elements. | image | textbook_images/how_elements_are_organized_22578.png |
L_0775 | how elements are organized | DD_0249 | Pictured below is a diagram of the periodic table. The periodic table is used today to classify elements. The elements in a periodic table are organized by the atomic number. The number of protons in an atom is what the atomic number represents on the chart. Rows on the periodic table are called periods. The columns in the periodic table are called groups. The modern periodic table have 18 groups. The elements are arranged in the periodic table by the atomic number from left to right from lowest atomic numbers to highest. | image | teaching_images/periodic_table_8162.png |
L_0775 | how elements are organized | DD_0250 | This image shows the Periodic table. It is a table of the chemical elements arranged in order of atomic number, usually in rows, so that elements with similar atomic structure (and hence similar chemical properties) appear in vertical columns. This ordering shows periodic trends, such as elements with similar behaviour in the same column. It also shows four rectangular blocks with some approximately similar chemical properties. In general, within one row (period) the elements are metals on the left, and non-metals on the right. The rows of the table are called periods; the columns are called groups. The periodic table provides a useful framework for analyzing chemical behaviour, and is widely used in chemistry and other sciences. | image | teaching_images/periodic_table_8157.png |
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