how many electrons will go in the first shell of chlorine
two
12613352
can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the "n"th shell can in principle hold up to 2("n") electrons. Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may
Electron shell
1925646
with two and eight electrons respectively. The first electron affinity of chlorine (the energy release when chlorine gains an electron) is +328.8 kJ per mole of chlorine atoms. Adding a second electron to chlorine requires energy, energy that cannot be recovered by formation of a chemical bond. The result is that chlorine will very often form a compound in which it has eight electrons in its outer shell (a complete octet). A sodium atom has a single electron in its outermost electron shell, the first and second shells again being full with two and eight electrons respectively. To remove this
Octet rule
69317
devastating because the existing gas masks were difficult to deploy and had not been broadly distributed. Chlorine is the second halogen, being a nonmetal in group 17 of the periodic table. Its properties are thus similar to fluorine, bromine, and iodine, and are largely intermediate between those of the first two. Chlorine has the electron configuration [Ne]3s3p, with the seven electrons in the third and outermost shell acting as its valence electrons. Like all halogens, it is thus one electron short of a full octet, and is hence a strong oxidising agent, reacting with many elements in order to complete
Chlorine
1925645
twice, once for each atom. In carbon dioxide each oxygen shares four electrons with the central carbon, two (shown in red) from the oxygen itself and two (shown in black) from the carbon. All four of these electrons are counted in both the carbon octet and the oxygen octet. Ionic bonding is common between pairs of atoms, where one of the pair is a metal of low electronegativity (such as sodium) and the second a nonmetal of high electronegativity (such as chlorine). A chlorine atom has seven electrons in its outer electron shell, the first and second shells being filled
Octet rule
12613352
can contain only a fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the "n"th shell can in principle hold up to 2("n") electrons. Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may
Electron shell
698544
fixed number of electrons: The first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the "n"th shell can in principle hold up to 2("n") electrons. Since electrons are electrically attracted to the nucleus, an atom's electrons will generally occupy outer shells only if the more inner shells have already been completely filled by other electrons. However, this is not a strict requirement: atoms may have two or even
Energy level
197016
other halogens, it is one electron short of a full octet and is hence a strong oxidising agent, reacting with many elements in order to complete its outer shell, although in keeping with periodic trends, it is the weakest oxidising agent among the stable halogens: it has the lowest electronegativity among them, just 2.66 on the Pauling scale (compare fluorine, chlorine, and bromine at 3.98, 3.16, and 2.96 respectively; astatine continues the trend with an electronegativity of 2.2). Elemental iodine hence forms diatomic molecules with chemical formula I, where two iodine atoms share a pair of electrons in order to
Iodine
61362
valence electrons are shared by two atoms: the resulting electrically neutral group of bonded atoms is termed a molecule. Atoms will share valence electrons in such a way as to create a noble gas electron configuration (eight electrons in their outermost shell) for each atom. Atoms that tend to combine in such a way that they each have eight electrons in their valence shell are said to follow the octet rule. However, some elements like hydrogen and lithium need only two electrons in their outermost shell to attain this stable configuration; these atoms are said to follow the "duet rule",
Chemistry
766345
shells and subshells despite the advances in understanding of the quantum-mechanical nature of electrons. An electron shell is the set of allowed states that share the same principal quantum number, "n" (the number before the letter in the orbital label), that electrons may occupy. An atom's "n"th electron shell can accommodate 2"n" electrons, "e.g." the first shell can accommodate 2 electrons, the second shell 8 electrons, the third shell 18 electrons and so on. The factor of two arises because the allowed states are doubled due to electron spin—each atomic orbital admits up to two otherwise identical electrons with opposite
Electron configuration
611314
angular momentum) We can imagine ourselves building a nucleus by adding protons and neutrons. These will always fill the lowest available level. Thus the first two protons fill level zero, the next six protons fill level one, and so on. As with electrons in the periodic table, protons in the outermost shell will be relatively loosely bound to the nucleus if there are only few protons in that shell, because they are farthest from the center of the nucleus. Therefore, nuclei which have a full outer proton shell will have a higher binding energy than other nuclei with a similar
Nuclear shell model
2678878
is a decrease in the screening of electron-nuclear attractions, so that the unpaired electrons can approach the nucleus more closely and the electron-nuclear attraction is increased. As a result of Hund's rule, constraints are placed on the way atomic orbitals are filled in the ground state using the Aufbau principle. Before any two electrons occupy an orbital in a subshell, other orbitals in the same subshell must first each contain one electron. Also, the electrons filling a subshell will have parallel spin before the shell starts filling up with the opposite spin electrons (after the first orbital gains a second
Hund's rule of maximum multiplicity
311766
so on). Each shell consists of one or more subshells (named s, p, d, f and g). As atomic number increases, electrons progressively fill these shells and subshells more or less according to the Madelung rule or energy ordering rule, as shown in the diagram. The electron configuration for neon, for example, is 1s 2s 2p. With an atomic number of ten, neon has two electrons in the first shell, and eight electrons in the second shell; there are two electrons in the s subshell and six in the p subshell. In periodic table terms, the first time an electron
Periodic table
8395501
forces. Electrons in an ionic bond tend to be mostly found around one of the two constituent atoms due to the large electronegativity difference between the two atoms; this is often described as one atom giving electrons to the other. This type of bond is generally formed between a metal and nonmetal, such as sodium and chlorine in NaCl. Sodium would give an electron to chlorine, forming a positively charged sodium ion and a negatively charged chloride ion. In a true covalent bond, the electrons are shared evenly between the two atoms of the bond; there is little or no
Intramolecular force
603692
"as bad a mode of warfare as poisoning the wells of the enemy." Playfair’s response was used to justify chemical warfare into the next century: Later, during the American Civil War, New York school teacher John Doughty proposed the offensive use of chlorine gas, delivered by filling a 10-inch (254 millimeter) artillery shell with two to three quarts (1.892.84 liters) of liquid chlorine, which could produce many cubic feet of chlorine gas. Doughty’s plan was apparently never acted on, as it was probably presented to Brigadier General James Wolfe Ripley, Chief of Ordnance, who was described as being congenitally immune
Chemical warfare
57628
a shell structure, in which each shell corresponds to a Bohr orbit. This model is even more approximate than the model of hydrogen, because it treats the electrons in each shell as non-interacting. But the repulsions of electrons are taken into account somewhat by the phenomenon of screening. The electrons in outer orbits do not only orbit the nucleus, but they also move around the inner electrons, so the effective charge Z that they feel is reduced by the number of the electrons in the inner orbit. For example, the lithium atom has two electrons in the lowest 1s orbit,
Bohr model
766348
assigned to each subshell placed as a superscript. For example, hydrogen has one electron in the s-orbital of the first shell, so its configuration is written 1s. Lithium has two electrons in the 1s-subshell and one in the (higher-energy) 2s-subshell, so its configuration is written 1s 2s (pronounced "one-s-two, two-s-one"). Phosphorus (atomic number 15) is as follows: 1s 2s 2p 3s 3p. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. The electron configuration can be visualized as the core electrons, equivalent to the noble gas of the preceding period, and the
Electron configuration
2908203
outermost electron shell; in a transition metal, a valence electron can also be in an inner shell. An atom with a closed shell of valence electrons (corresponding to an electron configuration sp) tends to be chemically inert. Atoms with one or two more valence electrons than are needed for a "closed" shell are highly reactive due to the following reasons: 1) It requires relatively low energy (compared to the lattice enthalpy) to remove the extra valence electrons to form a positive ion. 2) Because of their tendency either to gain the missing valence electrons (thereby forming a negative ion), or
Valence electron
11974434
20,000 times that of carbon dioxide. Organofluorine compounds persist in the environment due to the strength of the carbon–fluorine bond. Fluorine has no known metabolic role in mammals; a few plants synthesize organofluorine poisons that deter herbivores. Fluorine atoms have nine electrons, one fewer than neon, and electron configuration 1s2s2p: two electrons in a filled inner shell and seven in an outer shell requiring one more to be filled. The outer electrons are ineffective at nuclear shielding, and experience a high effective nuclear charge of 9 − 2 = 7; this affects the atom's physical properties. Fluorine's first ionization energy
Fluorine
20625315
in the middle, the two nuclei (holding the same charge) repulse each other. Therefore, it would require more energy to hold the two atoms together through the antibonding orbital. Each electron in the valence 1"s" shell of hydrogen come together to fill in the stabilizing bonding orbital. So, hydrogen prefers to exist as a diatomic, and not monatomic, molecule. When looking at helium, the atom holds two electrons in each valence 1"s" shell. When the two atomic orbitals come together, they first fill in the bonding orbital with two electrons, but unlike hydrogen, it has two electrons left, which must
Bonding molecular orbital
77710
carbon itself and four from the hydrogens bonded to it. Each hydrogen has a valence of one and is surrounded by two electrons (a duet rule) – its own one electron plus one from the carbon. The numbers of electrons correspond to full shells in the quantum theory of the atom; the outer shell of a carbon atom is the "n" = 2 shell, which can hold eight electrons, whereas the outer (and only) shell of a hydrogen atom is the "n" = 1 shell, which can hold only two. While the idea of shared electron pairs provides an effective
Covalent bond
12837265
by passing chlorine gas through iodobenzene in a cooled solution of chloroform. λ-iodanes such as diarylchloroiodanes have a pseudotrigonal bipyramidal geometry displaying apicophilicity with a phenyl group and a chlorine group at the apical positions and other phenyl group with two lone pair electrons in the equatorial positions. The λ-iodanes such as the Dess-Martin periodinane have square pyramidal geometries with 4 heteroatoms in basal positions and one apical phenyl group. Classical organic procedures exist for the preparation of iodosobenzene diacetate from peracetic acid and acetic acid, which was also first prepared by Willgerodt. Phenyliodine bis(trifluoroacetate), PIFA, or (bis(trifluoroacetoxy)iodo)benzene is a
Iodane
2341488
Lone pair In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom and is sometimes called a non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure. Electron pairs are therefore considered lone pairs if two electrons are paired but are not used in chemical bonding. Thus, the number of lone pair electrons plus the number of bonding electrons equals the total number of valence electrons around an atom. Lone pair is a concept used in valence shell electron
Lone pair
2613856
in solution. Chlorine dioxide is approximately 10 times more soluble in water than chlorine. The molecule ClO has an odd number of valence electrons, and therefore, it is a paramagnetic radical. Its electronic structure has long baffled chemists because none of the possible Lewis structures is very satisfactory. In 1933, L. O. Brockway proposed a structure that involved a three-electron bond. Chemist Linus Pauling further developed this idea and arrived at two resonance structures involving a double bond on one side and a single bond plus three-electron bond on the other. In Pauling's view the latter combination should represent a
Chlorine dioxide
19708608
the exterior cytoplasmic membrane. These enzymes normally utilize a metal ion cluster like Fe-S cluster to complete electron transfer cycle. Hydrogen is oxidized to generate two protons and two electrons. The removal of first chloride, which is performed by PCE-RDase, reduces PCE into TCE by reductive dehalogenation, where a hydride replaces the chlorine. The chloride lost from PCE gains the two electrons and the proton that accompanies them to form HCl. TCE can be reduced to "cis"-dichloroethene (cis-DCE) by either PCE-RDase or TCE-RDase. Subsequent reductions to vinyl chloride (VC) and ethylene are performed by TCE-RDase. The dechlorination of PCE to
Adsorbable organic halides
3308959
arresters, per NFPA 850. A potential target for a lightning strike, such as an outdoor television antenna, is attached to the terminal labeled A in the photograph. Terminal E is attached to a long rod buried in the ground. Ordinarily no current will flow between the antenna and the ground because there is extremely high resistance between B and C, and also between C and D. The voltage of a lightning strike, however, is many times higher than that needed to move electrons through the two air gaps. The result is that electrons go through the lightning arresters rather than
Lightning arrester
45640
[Ar]3d4s4p, with the seven electrons in the fourth and outermost shell acting as its valence electrons. Like all halogens, it is thus one electron short of a full octet, and is hence a strong oxidising agent, reacting with many elements in order to complete its outer shell. Corresponding to periodic trends, it is intermediate in electronegativity between chlorine and iodine (F: 3.98, Cl: 3.16, Br: 2.96, I: 2.66), and is less reactive than chlorine and more reactive than iodine. It is also a weaker oxidising agent than chlorine, but a stronger one than iodine. Conversely, the bromide ion is a
Bromine
10856821
across a row of the periodic table, the outer-shell electrons are pulled more and more strongly towards the nucleus and the atomic radius decreases. This can be used to explain a number of periodic trends such as atomic radius, first ionization energy (IE), electronegativity, and oxidizing. Core charge can also be calculated as 'atomic number' minus 'all electrons except those in the outer shell'. For example, chlorine (element 17), with electron configuration 1s 2s 2p 3s 3p, has 17 protons and 10 inner shell electrons (2 in the first shell, and 8 in the second) so: A core charge is
Core charge
12370696
attain this stable configuration, becoming a sodium cation in the process On the other hand, a chlorine atom, Cl, has 7 electrons in its valence shell, which is one short of the stable, filled shell with 8 electrons. Thus, a chlorine atom tends to "gain" an extra electron and attain a stable 8-electron configuration, becoming a chloride anion in the process: This driving force is what causes sodium and chlorine to undergo a chemical reaction, wherein the "extra" electron is transferred from sodium to chlorine, forming sodium cations and chloride anions. Being oppositely charged, these cations and anions form ionic
Ion
4789159
univalent atoms, because of their nature to form only one single bond. Hydrogen has only one "valence electron" and can form only one bond with an atom that has an incomplete outer shell. Chlorine has seven "valence electrons" and can form only one bond with an atom that donates a "valence electron" to complete chlorine's outer shell. However, chlorine can also have oxidation states from +1 to +7 and can form more than one bond by donating "valence electrons". Hydrogen has only one valence electron, but it can form bonds with more than one atom. In the bifluoride ion (),
Valence (chemistry)
1925647
outer electron requires only the first ionization energy, which is +495.8 kJ per mole of sodium atoms, a small amount of energy. By contrast, the second electron resides in the deeper second electron shell, and the second ionization energy required for its removal is much larger: +4562.4 kJ per mole. Thus sodium will, in most cases, form a compound in which it has lost a single electron and have a full outer shell of eight electrons, or octet. The energy required to transfer an electron from a sodium atom to a chlorine atom (the difference of the 1st ionization energy
Octet rule
592534
The way the atomic radius varies with increasing atomic number can be explained by the arrangement of electrons in shells of fixed capacity. The shells are generally filled in order of increasing radius, since the negatively charged electrons are attracted by the positively charged protons in the nucleus. As the atomic number increases along each row of the periodic table, the additional electrons go into the same outermost shell; whose radius gradually contracts, due to the increasing nuclear charge. In a noble gas, the outermost shell is completely filled; therefore, the additional electron of next alkali metal will go into
Atomic radius
9275
would be attracted to the chlorine because the effective nuclear charge on the outer electrons is +7 in chlorine but is only +1 in sodium. The electron pair is attracted so close to the chlorine atom that they are practically transferred to the chlorine atom (an ionic bond). However, if the sodium atom was replaced by a lithium atom, the electrons will not be attracted as close to the chlorine atom as before because the lithium atom is smaller, making the electron pair more strongly attracted to the closer effective nuclear charge from lithium. Hence, the larger alkali metal atoms
Alkali metal
197015
who identified iodine first, but both scientists acknowledged Courtois as the first to isolate the element. Iodine is the fourth halogen, being a member of group 17 in the periodic table, below fluorine, chlorine, and bromine; it is the heaviest stable member of its group. (The scarce and fugitive fifth halogen, the radioactive astatine, is not well-studied due to its expense and inaccessibility in large quantities, but appears to show various unusual properties due to relativistic effects.) Iodine has an electron configuration of [Kr]4d5s5p, with the seven electrons in the fifth and outermost shell being its valence electrons. Like the
Iodine
15135989
number of electrons: 2 in the first shell; 8 in the second shell; 18 in the third shell, and so on, each shell holding an increasing number of electrons. The chemical behaviour of all elements is explained by the number of electrons in their outer shells: to increase the energetic stability of their electron configurations atoms have a tendency to gain or lose electrons in such a way so as to achieve a full outer shell. Sodium, with 11 electrons – one in its outer-most occupied shell, will transfer an electron in the presence of fluorine to its outer-most occupied
Chemistry: A Volatile History
10785365
killing weeds, and increasing the longevity of cut flowers. Bleaches work by reacting with many colored organic compounds, such as natural pigments, and turning them into colorless ones. While most bleaches are oxidizing agents (chemicals that can remove electrons from other molecules), some are reducing agents (that donate electrons). Chlorine, a powerful oxidizer, is the active agent in many household bleaches. Since pure chlorine is a toxic corrosive gas, these products usually contain hypochlorite which releases chlorine when needed. "Bleaching powder" usually means a formulation containing calcium hypochlorite. Oxidizing bleaching agents that do not contain chlorine are usually based on
Bleach
12370699
energy of an atom is the energy required to detach its "n"th electron after the first "n − 1" electrons have already been detached. Each successive ionization energy is markedly greater than the last. Particularly great increases occur after any given block of atomic orbitals is exhausted of electrons. For this reason, ions tend to form in ways that leave them with full orbital blocks. For example, sodium has one "valence electron" in its outermost shell, so in ionized form it is commonly found with one lost electron, as . On the other side of the periodic table, chlorine has
Ion
2908219
band (to which valence electrons are excited by thermal energy). Valence electron In chemistry, a valence electron is an outer shell electron that is associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair. The presence of valence electrons can determine the element's chemical properties, such as its valence—whether it may bond with other elements and, if so, how readily and with how many. For a main
Valence electron
19943826
chlorine, that is, its strong affinity for electrons. It readily inserts itself into double bonds, including those of aromatic rings, to give chlorinated organic compound; which often explains its bleaching action, since many colored organic substances owe their color to compounds with such bonds. The extensive reactivity of chlorine is also responsible for its broad antimicrobial effect, since it can destroy or denature many proteins and other chemicals that are essential for their metabolism. The strength of chlorine-releasing solutions, as well as their dosage in uses like water chlorination and pool sanitization, is usually expressed mass concentration of "free chlorine"
Chlorine-releasing compounds
12837262
Iodane Iodanes are chemical compounds containing hypervalent iodine. These iodine compounds are hypervalent because the iodine atom in it contains more than the 8 electrons in the valence shell required for the octet rule. When iodine is complexed with a monodentate electronegative ligand such as chlorine, iodine compounds occur with a +3 oxidation number as iodine(III) or λ-iodanes or as a +5 oxidation number as iodine(V) or λ-iodanes. Iodine itself contains 7 valence electrons and in a λ-iodane three more are donated by the ligands making it a decet structure. λ-iodanes are dodecet molecules. In an ordinary iodine compound such
Iodane
12837271
a lactam with an enone group. Iodane Iodanes are chemical compounds containing hypervalent iodine. These iodine compounds are hypervalent because the iodine atom in it contains more than the 8 electrons in the valence shell required for the octet rule. When iodine is complexed with a monodentate electronegative ligand such as chlorine, iodine compounds occur with a +3 oxidation number as iodine(III) or λ-iodanes or as a +5 oxidation number as iodine(V) or λ-iodanes. Iodine itself contains 7 valence electrons and in a λ-iodane three more are donated by the ligands making it a decet structure. λ-iodanes are dodecet molecules.
Iodane
2642192
hard truths': that global energy demand is rising, that the supply of conventional energy will not be able to keep up, and that climate change is both real and dangerous." Between 1978 and 1995, Shell Oil produced polybutylene pipes, which corrode when exposed to chlorine. A class action lawsuit was filed in 1995 against Shell Oil when the polybutylene pipes caused flooding in many households in the U.S. and Canada. The settlement required Shell Oil to pay for the re-installation of piping for millions of houses for claims filed through May 2009. Shell Oil Company Shell Oil Company is the
Shell Oil Company
12613359
electrons in any one shell. This is because the subshells are filled according to the Aufbau principle. The first elements to have more than 32 electrons in one shell would belong to the g-block of period 8 of the periodic table. These elements would have some electrons in their subshell and thus have more than 32 electrons in the O shell (fifth principal shell). The valence shell is the outermost shell of an atom. Valence electrons in non-transition metal elements reside in this shell. Such elements with complete valence shells (noble gases) are the most chemically non-reactive, while those with
Electron shell
831666
element has four electrons in its valence shell, forming a valence electron configuration of nsnp. In flerovium's case, the trend will be continued and the valence electron configuration is predicted to be 7s7p; flerovium will behave similarly to its lighter congeners in many respects. Differences are likely to arise; a largely contributing effect is the spin–orbit (SO) interaction—the mutual interaction between the electrons' motion and spin. It is especially strong for the superheavy elements, because their electrons move faster than in lighter atoms, at velocities comparable to the speed of light. In relation to flerovium atoms, it lowers the 7s
Flerovium
12613360
only one electron in their valence shells (alkali metals) or just missing one electron from having a complete shell (halogens) are the most reactive. However, this terminology is somewhat misleading in the case of transition metals. In these elements, a valence electron can also be in an inner shell. Thus, the electrons that determine how an atom reacts chemically are those that travel farthest from the nucleus, that is, those with the highest energy, and not necessarily in the valence shell. The list below gives the elements arranged by increasing atomic number and shows the number of electrons per shell.
Electron shell
13095860
Argon-37 then de-excites itself via electron capture (half-life = 35 d) into chlorine-37 via the reaction These last reactions involve Auger electrons of specific energies. The detection of these electrons confirms that a neutrino event took place. Detection methods involve several hundred thousand liters of carbon tetrachloride (CCl) or tetrachloroethylene (CCl) stored in underground tanks. The representative terrestrial abundance of chlorine-37 is 24.22(4)% of chlorine atoms, with a normal range of 24.14–24.36% of chlorine atoms. When measuring deviations in isotopic composition, the usual reference point is "Standard Mean Ocean Chloride" (SMOC), although a NIST Standard Reference Material (975a) also exists.
Chlorine-37
473406
is greater than the orbital binding energy. An emitted electron will have a kinetic energy of: where formula_2, formula_3, formula_4 are respectively the core level, first outer shell, and second outer shell electron binding energies (measured from the vacuum level) which are taken to be positive. The apostrophe (tic) denotes a slight modification to the binding energy of the outer shell electrons due to the ionized nature of the atom; often however, this energy modification is ignored in order to ease calculations. Since orbital energies are unique to an atom of a specific element, analysis of the ejected electrons can
Auger electron spectroscopy
6979463
how they also change the matter around them. To color their flames, pyrotechnicians will generally use metal salts. Specific combinations of fuels and co-solvents are required in order to dissolve the necessary chemicals. Color enhancers (usually chlorine donors) are frequently added too, the most common of which is polyvinyl chloride. A practical use of colored fire is the flame test, where metal cations are tested by placing the sample in a flame and analyzing the color produced. Emitted colors depend on the electronic configuration of the elements involved. Heat energy from the flame excites electrons to a higher quantum level,
Colored fire
2908202
Valence electron In chemistry, a valence electron is an outer shell electron that is associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair. The presence of valence electrons can determine the element's chemical properties, such as its valence—whether it may bond with other elements and, if so, how readily and with how many. For a main group element, a valence electron can exist only in the
Valence electron
10498
is known as the valence shell, and the electrons in that shell are called valence electrons. The number of valence electrons determines the bonding behavior with other atoms. Atoms tend to chemically react with each other in a manner that fills (or empties) their outer valence shells. For example, a transfer of a single electron between atoms is a useful approximation for bonds that form between atoms with one-electron more than a filled shell, and others that are one-electron short of a full shell, such as occurs in the compound sodium chloride and other chemical ionic salts. However, many elements
Atom
78041
many purposes, these descriptions are not precisely correct. Oxidation is better defined as an increase in oxidation state, and reduction as a decrease in oxidation state. In practice, the transfer of electrons will always change the oxidation state, but there are many reactions that are classed as "redox" even though no electron transfer occurs (such as those involving covalent bonds). In the following redox reaction, hazardous sodium metal reacts with toxic chlorine gas to form the ionic compound sodium chloride, or common table salt: In the reaction, sodium metal goes from an oxidation state of 0 (as it is a
Chemical reaction
631837
high electric field near the points of the nearby comb (2). At the points, the field becomes strong enough to ionize air molecules, and the electrons are attracted to the outside of the belt while positive ions go to the comb. At the comb (2) they are neutralized by electrons that were on the comb, thus leaving the comb and the attached outer shell (1) with fewer net electrons. By the principle illustrated in the Faraday ice pail experiment, i.e. by Gauss's law, the excess positive charge is accumulated on the outer surface of the outer shell (1), leaving no
Van de Graaff generator
774291
lower. By element 132, the predominant most stable oxidation state will be only +6; this is further reduced to +3 and +4 by element 144, and at the end of the superactinide series it will be only +2 (and possibly even 0) because the 6f shell, which is being filled at that point, is deep inside the electron cloud and the 8s and 8p electrons are bound too strongly to be chemically active. The 5g shell should be filled at element 144 and the 6f shell at around element 154, and at this region of the superactinides the 8p electrons
Extended periodic table
7785182
atom uses for bonding. This is equal to the number of electrons in its valence shell if all the valence shell electrons are used for bonding. If they are not, the remainder will form non-bonding electron pairs, usually known as "lone pairs". The "valence of a bond", S, is defined as the number of electron pairs forming the bond. In general this is not an integral number. Since each of the terminal atoms contributes equal numbers of electrons to the bond, the bond valence is also equal to the number of valence electrons that each atom contributes. Further, since within
Bond valence method
12613358
can overlap (see "valence shells" and "Aufbau principle"). Each subshell is constrained to hold electrons at most, namely: Therefore, the K shell, which contains only an subshell, can hold up to 2 electrons; the L shell, which contains an and a , can hold up to 2 + 6 = 8 electrons, and so forth; in general, the "n"th shell can hold up to 2"n" electrons. Although that formula gives the maximum in principle, in fact that maximum is only "achieved" (by known elements) for the first four shells (K, L, M, N). No known element has more than 32
Electron shell
4944127
clusters show deviations in the number of electrons that form a closed shell as the potential is defined by the shape of the positive nuclei.) Superatoms tend to behave chemically in a way that will allow them to have a closed shell of electrons, in this new counting scheme. Therefore, a superatom with one more electron than a full shell should give up that electron very easily, similar to an alkali metal, and a cluster with one electron short of full shell should have a large electron affinity, such as a halogen. Certain aluminium clusters have superatom properties. These aluminium
Superatom
125520
electron has its oxidation state decrease. For example, when atomic sodium reacts with atomic chlorine, sodium donates one electron and attains an oxidation state of +1. Chlorine accepts the electron and its oxidation state is reduced to −1. The sign of the oxidation state (positive/negative) actually corresponds to the value of each ion's electronic charge. The attraction of the differently charged sodium and chlorine ions is the reason they then form an ionic bond. The loss of electrons from an atom or molecule is called oxidation, and the gain of electrons is reduction. This can be easily remembered through the
Electrochemistry
2908213
kind of nonmetal element is a halogen (e.g., fluorine (F) or chlorine (Cl)). Such an atom has the following electron configuration: sp; this requires only one additional valence electron to form a closed shell. To form an ionic bond, a halogen atom can remove an electron from another atom in order to form an anion (e.g., F, Cl, etc.). To form a covalent bond, one electron from the halogen and one electron from another atom form a shared pair (e.g., in the molecule H–F, the line represents a shared pair of valence electrons, one from H and one from F).
Valence electron
467403
an excimer (excited dimer) until the electrons return to the ground state. This entity is formed because the xenon atom tends to complete the outermost electronic shell by adding an electron from a neighboring xenon atom. The typical lifetime of a xenon excimer is 1–5 ns, and the decay releases photons with wavelengths of about 150 and 173 nm. Xenon can also form excimers with other elements, such as the halogens bromine, chlorine, and fluorine. Although xenon is rare and relatively expensive to extract from the Earth's atmosphere, it has a number of applications. Xenon is used in light-emitting devices
Xenon
1616151
more positive "E" than metals. Atoms whose anions are more stable than neutral atoms have a greater "E". Chlorine most strongly attracts extra electrons; mercury most weakly attracts an extra electron. The electron affinities of the noble gases have not been conclusively measured, so they may or may not have slightly negative values. "E" generally increases across a period (row) in the periodic table prior to reaching group 18. This is caused by the filling of the valence shell of the atom; a group 17 atom releases more energy than a group 1 atom on gaining an electron because it
Electron affinity
9794877
many countries, CFCs can stay in the atmosphere for about 50-500 years. This cause many chlorine radicals to be produced and hence a significant amount of ozone molecules are decomposed before the chlorine radicals are able to react with chlorine monoxide to form Dichlorine monoxide. Chlorine monoxide Chlorine monoxide is a chemical radical with the chemical formula ClO. It plays an important role in the process of ozone depletion. In the stratosphere, chlorine atoms react with ozone molecules to form chlorine monoxide and oxygen. This reaction causes the depletion of the ozone layer. This reaction can go on and the
Chlorine monoxide
313212
that all atoms with 17 protons are chlorine atoms. The chemical properties of each atom are determined by the number of (negatively charged) electrons, which for neutral atoms is equal to the number of (positive) protons so that the total charge is zero. For example, a neutral chlorine atom has 17 protons and 17 electrons, whereas a Cl anion has 17 protons and 18 electrons for a total charge of −1. All atoms of a given element are not necessarily identical, however, as the number of neutrons may vary to form different isotopes, and energy levels may differ forming different
Proton
15135990
shell, which contains seven electrons. The result is both sodium and fluorine now have a full outer shell, and Sodium Fluoride is formed. This theory explained why all elements react in the way they do and why some formed the compounds they do, while others did not. It also explained why elements had the physical properties they did, which in turn explained why the periodic table had the shape it did. However, there was one fundamental question left unanswered: how many elements were there – could there be an infinite number of elements between Hydrogen and Uranium? Early 20th century
Chemistry: A Volatile History
12370695
is called "ionization". Atoms can be ionized by bombardment with radiation, but the more usual process of ionization encountered in chemistry is the transfer of electrons between atoms or molecules. This transfer is usually driven by the attaining of stable ("closed shell") electronic configurations. Atoms will gain or lose electrons depending on which action takes the least energy. For example, a sodium atom, Na, has a single electron in its valence shell, surrounding 2 stable, filled inner shells of 2 and 8 electrons. Since these filled shells are very stable, a sodium atom tends to lose its extra electron and
Ion
57627
(see Electron shell and the later discussion of the "Shell Model of the Atom" below). This was established empirically before Bohr presented his model. Bohr extended the model of hydrogen to give an approximate model for heavier atoms. This gave a physical picture that reproduced many known atomic properties for the first time. Heavier atoms have more protons in the nucleus, and more electrons to cancel the charge. Bohr's idea was that each discrete orbit could only hold a certain number of electrons. After that orbit is full, the next level would have to be used. This gives the atom
Bohr model
763884
in its valence shell, forming a valence electron configuration of nsnp. In moscovium's case, the trend should be continued and the valence electron configuration is predicted to be 7s7p; therefore, moscovium will behave similarly to its lighter congeners in many respects. However, notable differences are likely to arise; a largely contributing effect is the spin–orbit (SO) interaction—the mutual interaction between the electrons' motion and spin. It is especially strong for the superheavy elements, because their electrons move much faster than in lighter atoms, at velocities comparable to the speed of light. In relation to moscovium atoms, it lowers the 7s
Moscovium
78044
low-energy noble gas configuration, and therefore alkali metals and halogens will donate and accept one electron respectively. Noble gases themselves are chemically inactive. An important class of redox reactions are the electrochemical reactions, where electrons from the power supply are used as the reducing agent. These reactions are particularly important for the production of chemical elements, such as chlorine or aluminium. The reverse process in which electrons are released in redox reactions and can be used as electrical energy is possible and used in batteries. In complexation reactions, several ligands react with a metal atom to form a coordination complex.
Chemical reaction
520694
due to a charge build up. Take the previous example in which an average of 100 electrons go from point A to point B every nanosecond. During the first half of a nanosecond we would expect 50 electrons to arrive at point B on the average, but in a particular half nanosecond there might well be 60 electrons which arrive there. This will create a more negative electric charge at point B than average, and that extra charge will tend to "repel" the further flow of electrons from leaving point A during the remaining half nanosecond. Thus the net current
Shot noise
8352096
energies in the band, from the bottom of the band formula_10 to the top of the band formula_11. Because electrons are fermions, the density of conduction electrons at any particular energy,formula_13 is the product of the density of states,formula_14 or how many conducting states are possible, with the Fermi-Dirac distribution,formula_15 which tells us the portion of those states which will actually have electrons in them. In order to simplify the calculation, instead of treating the electrons as Fermions, according to the Fermi-dirac distribution, we instead treat them as a classical non-interacting gas, which is given by the Maxwell–Boltzmann distribution. This
Charge carrier density
69336
then be separated and purified from chlorine trifluoride and its reactants. Its properties are mostly intermediate between those of chlorine and fluorine. It will react with many metals and nonmetals from room temperature and above, fluorinating them and liberating chlorine. It will also act as a chlorofluorinating agent, adding chlorine and fluorine across a multiple bond or by oxidation: for example, it will attack carbon monoxide to form carbonyl chlorofluoride, COFCl. It will react analogously with hexafluoroacetone, (CF)CO, with a potassium fluoride catalyst to produce heptafluoroisopropyl hypochlorite, (CF)CFOCl; with nitriles RCN to produce RCFNCl; and with the sulfur oxides SO
Chlorine
766360
configuration), and have notable similarities in their chemical properties. In general, the periodicity of the periodic table in terms of periodic table blocks is clearly due to the number of electrons (2, 6, 10, 14...) needed to fill s, p, d, and f subshells. The outermost electron shell is often referred to as the "valence shell" and (to a first approximation) determines the chemical properties. It should be remembered that the similarities in the chemical properties were remarked on more than a century before the idea of electron configuration. It is not clear how far Madelung's rule "explains" (rather than
Electron configuration
9450074
the same state (Pauli exclusion principle). So the lowest-energy state of the nucleus is one where nucleons fill all energy levels from the bottom up to some level. A nucleus with full shells is exceptionally stable, as will be explained. As with electrons in the electron shell model, protons in the outermost shell are relatively loosely bound to the nucleus if there are only few protons in that shell, because they are farthest from the center of the nucleus. Therefore, nuclei which have a full outer proton shell will be more tightly bound and have a higher binding energy than
Nuclear structure
280093
electrons. In 1916, Gilbert N. Lewis formulated the "octet rule", which concluded an octet of electrons in the outer shell was the most stable arrangement for any atom; this arrangement caused them to be unreactive with other elements since they did not require any more electrons to complete their outer shell. In 1962, Neil Bartlett discovered the first chemical compound of a noble gas, xenon hexafluoroplatinate. Compounds of other noble gases were discovered soon after: in 1962 for radon, radon difluoride (), which was identified by radiotracer techniques and in 1963 for krypton, krypton difluoride (). The first stable compound
Noble gas
6641742
Energy filtered transmission electron microscopy Energy-filtered transmission electron microscopy (EFTEM) is a technique used in transmission electron microscopy, in which only electrons of particular kinetic energies are used to form the image or diffraction pattern. The technique can be used to aid chemical analysis of the sample in conjunction with complementary techniques such as electron crystallography. If a very thin sample is illuminated with a beam of high-energy electrons, then a majority of the electrons will pass unhindered through the sample but some will interact with the sample, being scattered elastically or inelastically (phonon scattering, plasmon scattering or inner shell
Energy filtered transmission electron microscopy
19943825
the air at swimming pools where chlorine is used as the disinfectant, can lead to the development of atopic asthma. Ntrogen trichloride is also a very sensitive explosive. Chlorine releasing products may also cause corrosion of many materials and unintended bleaching of colored products. Sodium thiosulfate is an effective chlorine neutralizer. Rinsing with a 5 mg/L solution, followed by washing with soap and water, will remove chlorine odor from the hands. Specific compounds in this family include: Chlorine releasing bleaches and disinfectants depend on the strong reactivity of chlorine towards many organic compounds; in particular, its strong oxidizing character of
Chlorine-releasing compounds
18315860
ion with a hole, [K], collides with another core ion without a hole, [K], to form a near-dissociative K-shell MIMS (K-MIMS) and its excess energy transforms into the vibration energy. Such a vibrationally hot K-MIMS in the plasma is denoted here by <nowiki></nowiki>K + K<nowiki></nowiki>. Subsequently, a Rydberg-like pseudo-L-shell forms around the K-MIMS core ions that are proposed to go through a rapid relaxation into the lowest vibrational state by ionizing a number of electrons in the pseudo-L-shell. The vibrationally cold K-MIMS without an L-shell hole is denoted by [KKL]. The vibrational energy is quenched by ionizing the bound [KKL]
Metastable inner-shell molecular state
799960
Electron energy loss spectroscopy In electron energy loss spectroscopy (EELS) a material is exposed to a beam of electrons with a known, narrow range of kinetic energies. Some of the electrons will undergo inelastic scattering, which means that they lose energy and have their paths slightly and randomly deflected. The amount of energy loss can be measured via an electron spectrometer and interpreted in terms of what caused the energy loss. Inelastic interactions include phonon excitations, inter- and intra-band transitions, plasmon excitations, inner shell ionizations, and Cherenkov radiation. The inner-shell ionizations are particularly useful for detecting the elemental components of
Electron energy loss spectroscopy
1773285
material subjected to ever-increasing pressure will compact more, and, for electrons within it, their delocalization, Δ"x", will decrease. Thus, as dictated by the uncertainty principle, the spread in the momenta of the electrons, Δ"p", will grow. Thus, no matter how low the temperature drops, the electrons must be travelling at these large "Heisenberg speeds", contributing to the pressure. When the pressure due to this "Heisenberg motion" exceeds that of the pressure from the thermal motions of the electrons, the electrons are referred to as degenerate, and the material is termed degenerate matter. This analysis is true even at almost zero
Electron degeneracy pressure
3922706
a point. The shell numbers start at 1 and increase indefinitely. Each shell of number contains ² orbitals. Each orbital is characterized by its number , where takes integer values from "0" to −1, and its angular momentum number , where takes integer values from + to −. By means of a variety of approximations and extensions, physicists were able to extend their work on hydrogen to more complex atoms containing many electrons. Atomic spectra measure radiation absorbed or emitted by electrons "jumping" from one "state" to another, where a state is represented by values of , , and .
Spin quantum number
5248946
transitions, the modern view associates electron shells with principal quantum numbers "n", with each shell containing 2"n" electrons, giving the "n" = 1 "shell" of atoms 2 electrons, and the "n" = 2 shell 8 electrons. The empirical value of 7.4 for Moseley's formula_26 is thus associated with "n" = 2 to 3, then called L-alpha transitions (not to be confused with Lyman-alpha transitions), and occurring from the "M to L" shells in Bohr's later notation. This value of 7.4 is now known to represent an electron screening effect for a fraction (specifically 0.74) of the total of 10 electrons
Moseley's law
2824732
all atoms so far discovered. For a given value of the principal quantum number "n", the possible values of "ℓ" range from 0 to "n" − 1; therefore, the "n" = 1 shell only possesses an s subshell and can only take 2 electrons, the "n" = 2 shell possesses an s and a p subshell and can take 8 electrons overall, the "n" = 3 shell possesses s, p, and d subshells and has a maximum of 18 electrons, and so on. Generally speaking, the maximum number of electrons in the "n"th energy level is 2"n". The angular momentum
Azimuthal quantum number
9769150
non life-threatening, but nonetheless highly traumatic, injuries. Chlorine was used as a poison gas in World War I, but was delivered by artillery shell, unlike the modern stationary or car bombs. Still, its function as a weapon in both instances is similar. Low level exposure results in burning sensations to the eyes, nose and throat, usually accompanied by dizziness, nausea and vomiting. Higher levels of exposure can cause fatal lung damage; but because the gas is heavier than air it will not dissipate until well after an explosion, it is generally considered ineffective as an improvised chemical weapon. In February
Chlorine bombings in Iraq
2844875
Open shell In the context of atomic orbitals, an open shell is a valence shell which is not completely filled with electrons or that has not given all of its valence electrons through chemical bonds with other atoms or molecules during a chemical reaction. Atoms generally reach a noble gas configuration in a molecule. The noble gases (He, Ne, Ar, Kr, Xe, Rn) are less reactive and have configurations 1s (He), 1s2s2p (Ne), 1s2s2p3s3p (Ar), etc. For molecules it signifies that there are unpaired electrons. In molecular orbital theory, this leads to molecular orbitals that are singly occupied. In computational
Open shell
1546168
oxidized to ferricyanide (). Simultaneously, the oxidizer chlorine is reduced to chloride. Strong reducing agents easily lose (or donate) electrons. An atom with a relatively large atomic radius tends to be a better reductant. In such species, the distance from the nucleus to the valence electrons is so long that these electrons are not strongly attracted. These elements tend to be strong reducing agents. Good reducing agents tend to consist of atoms with a low electronegativity, the ability of an atom or molecule to attract bonding electrons, and species with relatively small ionization energies serve as good reducing agents too.
Reducing agent
2239991
light wave absorption include: In electronic absorption, the frequency of the incoming light wave is at or near the energy levels of the electrons within the atoms which compose the substance. In this case, the electrons will absorb the energy of the light wave and increase their energy state, often moving outward from the nucleus of the atom into an outer shell or orbital. The atoms that bind together to make the molecules of any particular substance contain a number of electrons (given by the atomic number Z in the periodic chart). Recall that all light waves are electromagnetic in
Transparency and translucency
57630
integer. But Moseley's law experimentally probes the innermost pair of electrons, and shows that they do see a nuclear charge of approximately Z−1, while the outermost electron in an atom or ion with only one electron in the outermost shell orbits a core with effective charge Z−k where k is the total number of electrons in the inner shells. The shell model was able to qualitatively explain many of the mysterious properties of atoms which became codified in the late 19th century in the periodic table of the elements. One property was the size of atoms, which could be determined
Bohr model
300919
light received from the first shell. Thus each shell of a given thickness will produce the same net amount of light regardless of how far away it is. That is, the light of each shell adds to the total amount. Thus the more shells, the more light; and with infinitely many shells, there would be a bright night sky. While dark clouds could obstruct the light, these clouds would heat up, until they were as hot as the stars, and then radiate the same amount of light. Kepler saw this as an argument for a finite observable universe, or at
Olbers' paradox
3780564
of electrochemical engineering. The most common chloralkali process involves the electrolysis of aqueous sodium chloride (a brine) in a membrane cell. Saturated brine is passed into the first chamber of the cell where the chloride ions are oxidised at the anode, losing electrons to become chlorine gas (A in figure): At the cathode, positive hydrogen ions pulled from water molecules are reduced by the electrons provided by the electrolytic current, to hydrogen gas, releasing hydroxide ions into the solution (C in figure): The ion-permeable ion exchange membrane at the center of the cell allows the sodium ions (Na) to pass
Chloralkali process
7809374
chemical bonding and reactions by screening the positive charge of the atomic nucleus from the valence shell of electrons. In transition metals, the distinction between core and valence electrons is less distinct with electrons in the highest d-shell acting more like valence electrons than core electrons. A more complex explanation of the difference between core and valence electrons can be described with atomic orbital theory. In atoms with a single electron the energy of an orbital is determined exclusively by the principle quantum number n. The n=1 orbital has the lowest possible energy in the atom. For large n, the
Core electron
122318
of chlorine. The effect is much larger than could be explained by the negative charge being shared among a larger number of oxygen atoms, which would lead to a difference in p"K" of log() = –0.6 between hypochlorous acid and perchloric acid. As the oxidation state of the central chlorine atom increases, more electron density is drawn from the oxygen atoms onto the chlorine, reducing the partial negative charge on the oxygen atoms and increasing the acidity. The electronegativity of an atom changes depending on the hybridization of the orbital employed in bonding. Electrons in s orbitals are held more
Electronegativity
9274
heavier alkali metals. Adding the atomisation and first ionisation energies gives a quantity closely related to (but not equal to) the activation energy of the reaction of an alkali metal with another substance. This quantity decreases going down the group, and so does the activation energy; thus, chemical reactions can occur faster and the reactivity increases down the group. Electronegativity is a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself. If the bond between sodium and chlorine in sodium chloride were covalent, the pair of shared electrons
Alkali metal
5600532
of magnetization gives these compounds a very high magnetic coercivity (resistance to being demagnetized). Second, atoms of rare-earth elements can have high magnetic moments because their orbital electron structure contains many unpaired electrons, in contrast to other elements, in which almost all of the electrons exist in pairs with opposite spins, so their magnetic fields cancel out. This is a consequence of incomplete filling of the f-shell, which can contain up to 7 unpaired electrons. In a magnet it is the unpaired electrons, aligned so they spin in the same direction, which generate the magnetic field. This gives the materials
Rare-earth magnet
9794875
Chlorine monoxide Chlorine monoxide is a chemical radical with the chemical formula ClO. It plays an important role in the process of ozone depletion. In the stratosphere, chlorine atoms react with ozone molecules to form chlorine monoxide and oxygen. This reaction causes the depletion of the ozone layer. This reaction can go on and the ClO· radicals can go on to react as such: regenerating the chlorine radical. In this way, the overall reaction for the decomposition of ozone is catalyzed by chlorine, as ultimately chlorine remains unchanged. The overall reaction is: This has been a significant impact of the
Chlorine monoxide
69319
electron affinity, enthalpy of dissociation of the X molecule (X = Cl, Br, I), ionic radius, and X–X bond length. (Fluorine is anomalous due to its small size.) All four stable halogens experience intermolecular van der Waals forces of attraction, and their strength increases together with the number of electrons among all homonuclear diatomic halogen molecules. Thus, the melting and boiling points of chlorine are intermediate between those of fluorine and bromine: chlorine melts at −101.0 °C and boils at −34.0 °C. As a result of the increasing molecular weight of the halogens down the group, the density and heats
Chlorine
6641743
ionisation). Inelastic scattering results in both a loss of energy and a change in momentum, which in the case of inner shell ionisation is characteristic of the element in the sample. If the electron beam emerging from the sample is passed through a magnetic prism, then the flight path of the electrons will vary depending on their energy. This technique is used to form spectra in Electron energy loss spectroscopy (EELS), but it is also possible to place an adjustable slit to allow only electrons with a certain range of energies through, and reform an image using these electrons on
Energy filtered transmission electron microscopy
326985
relatively narrow (d-)bands, which are poorly delocalized. Generally, strong delocalization in a solid due to large overlap with neighboring wave functions means that there will be a large Fermi velocity; this means that the number of electrons in a band is less sensitive to shifts in that band's energy, implying a weak magnetism. This is why s- and p-type metals are typically either Pauli-paramagnetic or as in the case of gold even diamagnetic. In the latter case the diamagnetic contribution from the closed shell inner electrons simply wins over the weak paramagnetic term of the almost free electrons. Stronger magnetic
Paramagnetism
7240403
Electron spectroscopy Electron spectroscopy is an analytical technique to study the electronic structure and its dynamics in atoms and molecules. In general an excitation source such as x-rays, electrons or synchrotron radiation will eject an electron from an inner-shell orbital of an atom. Detecting photoelectrons that are ejected by x-rays is called x-ray photoelectron spectroscopy (XPS) or electron spectroscopy for chemical analysis (ESCA). Detecting electrons that are ejected from higher orbitals to conserve energy during electron transitions is called Auger electron spectroscopy (AES). Experimental applications include high-resolution measurements on the intensity and angular distributions of emitted electrons as well as
Electron spectroscopy
763891
may display closed-shell or noble gas-like properties; if this is the case, moscovium will likely be typically monovalent as a result, since the cation Mc will have the same electron configuration as flerovium, perhaps giving moscovium some alkali metal character. However, the Mc cation would behave like its true lighter homolog Bi. The 7s electrons are too stabilized to be able to contribute chemically and hence the +5 state should be impossible and moscovium may be considered to have only three valence electrons. Moscovium would be quite a reactive metal, with a standard reduction potential of −1.5 V for the
Moscovium
18355668
2014, Marine Corps Maj. Gen. James Lariviere told Congress that “We have a no-touch policy and a three-foot separation rule with local nationals”…“A typical soldier’s day will be to get up, have their temperature taken, go out and perform whatever task they are there to do. They will only eat approved food and drink bottled water and wash their hands in chlorine solution. When they get back to their compounds, they will have their temperature taken and do a chlorine wash again.” The Chief of Staff of the United States Army, Raymond T. Odierno, ordered on October 27 a 21-day
Operation United Assistance
4785312
or used in spot mode to produce excitation of various effects in the sample. Among these effects are: phonon excitation (heat), cathodoluminescence (visible light fluorescence), continuum X-ray radiation (bremsstrahlung), characteristic X-ray radiation, secondary electrons (plasmon production), backscattered electron production, and Auger electron production. When the beam electrons (and scattered electrons from the sample) interact with bound electrons in the innermost electron shells of the atoms of the various elements in the sample, they can scatter the bound electrons from the electron shell producing a vacancy in that shell (ionization of the atom). This vacancy is unstable and must be filled
Electron microprobe
12949477
electrons would be removed from the ("n" − 1)d shell first. Experimentally it has been observed that not only are the "n"s electrons removed first, even for unionized complexes all of the valence electrons are located in the ("n" − 1)d orbitals. There are various hand waving arguments for this phenomenon including that "the "n"s electrons are farther away from the nuclei and thus ionized first" while ignoring results based on neutral complexes. This poor explanation avoids the basic problems with the standard electron configuration model. The standard electron configuration model assumes a hydrogen-like atom removed from all other atoms.
D electron count
2263686
of molecules with larger, more dispersed electron clouds. The polarizability is a measure of ease with which electrons can be redistributed; a large polarizability implies that the electrons are more easily redistributed. This trend is exemplified by the halogens (from smallest to largest: F, Cl, Br, I). Fluorine and chlorine are gases at room temperature, bromine is a liquid, and iodine is a solid.The London forces are thought to be arise from the motion of electrons.Thus the forces of attraction b/w the induced momentary dipole are called London forces. The first explanation of the attraction between noble gas atoms was
London dispersion force