Anions electron configuration

One aspect that reflects the electronic configuration of fullerenes relates to the electrochemically induced reduction and oxidation processes in solution. In good agreement with the tlireefold degenerate LUMO, the redox chemistry of [60]fullerene, investigated primarily with cyclic voltammetry and Osteryoung square wave voltammetry, unravels six reversible, one-electron reduction steps with potentials that are equally separated from each other. The separation between any two successive reduction steps is -450 50 mV. The low reduction potential (only -0.44 V versus SCE) of the process, that corresponds to the generation of the rt-radical anion 131,109,110,111 and 1121, deserves special attention. 

Whether an element is the source of the cation or anion in an ionic bond depends on several factors for which the periodic table can serve as a guide In forming ionic compounds elements at the left of the periodic table typically lose electrons giving a cation that has the same electron configuration as the nearest noble gas Loss of an elec tron from sodium for example yields Na which has the same electron configuration as neon... 

Elements at the right of the periodic table tend to gam electrons to reach the elec tron configuration of the next higher noble gas Adding an electron to chlorine for exam pie gives the anion Cl which has the same closed shell electron configuration as the noble gas argon... 

Transfer of an electron from a sodium atom to a chlorine atom yields a sodium cation and a chloride anion both of which have a noble gas electron configuration... 

UV/Vis Spectra for Molecules and Ions When a molecule or ion absorbs ultraviolet or visible radiation it undergoes a change in its valence electron configuration. The valence electrons in organic molecules, and inorganic anions such as oc-... 

As befits the electron configuration of elemental calcium, the metal is very reactive, readily losing two valence electrons to form the dispositive ion. In aqueous solution and ia its compounds, is colorless. Most calcium compounds ate white, unless the cation is paired with a colored anion. The ion... 

Figure 11.15 shows the Fliickel MOs of cyclopentadienyl anion. Like benzene and cyclo-heptatrienyl cation, cyclopentadienyl anion has six tt electrons and a closed-shell electron configuration. 

Active Figure 15.11 Energy levels of the five cyclopentadienyl molecular orbitals. Only the six-7r-electron cyclopentadienyl anion has a filled-shell configuration leading to aromaticity. Sign in at www.thomsonedu.com to see a simulation based on this figure and to take a short quiz. 

As pointed out in Chapter 2, elements close to a noble gas in the periodic table form ions that have the same number of electrons as the noble-gas atom. This means that these ions have noble-gas electron configurations. Thus the three elements preceding neon (N, O, and F) and the three elements following neon (Na, Mg, and Al) all form ions with the neon configuration, is22s22p6. The three nonmetal atoms achieve this structure by gaining electrons to form anions ... 

FIGURE 2.3 When nonmetal atoms acquire electrons and form anions, they do so until they have reached the electron configuration of the next noble gas. 

To predict the electron configuration of a monatomic cation, remove outermost electrons in the order np, ns, and (n — l)d fora monatomic anion, add electrons until the next noble-gas configuration has been reached. The transfer of electrons results in the formation of an octet (or duplet) of electrons in the valence shell on each of the atoms metals achieve an octet (or duplet) by electron loss and nonmetals achieve it by electron gain. 

The dominant features which control the stoichiometry of transition-metal complexes relate to the relative sizes of the metal ions and the ligands, rather than the niceties of electronic configuration. You will recall that the structures of simple ionic solids may be predicted with reasonable accuracy on the basis of radius-ratio rules in which the relative ionic sizes of the cations and anions in the lattice determine the structure adopted. Similar effects are important in determining coordination numbers in transition-metal compounds. In short, it is possible to pack more small ligands than large ligands about a metal ion of a given size. 

The electron configurations of atomic ions are written using the same procedure as for neutral atoms, taking into account the proper number of electrons. An anion has one additional electron for each unit of negative charge. A cation has one fewer electron for each unit of positive charge. 

Isoelectronic species must have the same number of electrons, and each element has a different atomic number, atoms of different elements cannot be isoelectronic. Two different cations may be isoelectronic, as may two different anions, or an anion and a cation. An example would be two anions (or two cations, or an anion and a cation) that have the electron configuration of a nearby noble gas, such as 02 and F", Na+ and Mg2+, or F and Na+. 

The sum of all the superscripts should be equal to the number of electrons in the atom (the atomic number, Z). Electronic configurations can also be written for cations and anions. 

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