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Electron affinity can be defined in two equivalent ways. First, as the energy that is released by adding an electron to an isolated gaseous atom. The second (reverse) definition is that electron affinity is the energy required to remove an electron from a singly charged gaseous negative ion.
The electron affinity of molecules is a complicated function of their electronic structure. For instance the electron affinity for benzene is negative, as is that of naphthalene, while those of anthracene, phenanthrene and pyrene are positive. In silico experiments show that the electron affinity of hexacyanobenzene surpasses that of fullerene. [5]
The electron affinity (usually given by the symbol in solid state physics) gives the energy difference between the lower edge of the conduction band and the vacuum level of the semiconductor. The band gap (usually given the symbol E g {\displaystyle E_{\rm {g}}} ) gives the energy difference between the lower edge of the conduction band and the ...
The valence d-subshell often "borrows" one electron (in the case of thorium two electrons) from the valence f-subshell. For example, in uranium 92 U, according to the Madelung rule, the 5f subshell (n + l = 5 + 3 = 8) is occupied before the 6d subshell (n + l = 6 + 2 = 8). The rule then predicts the electron configuration [Rn] 5f 4 7s 2 where ...
C 6 Cl 4 O 2: Carbonate: CO 3 2 ... where I is the ionization potential and A the electron affinity. ... The equation predicts reversal of acids and base strengths.
For example, the electron binding energy for removing a 3p 3/2 electron from the chloride ion is the minimum amount of energy required to remove an electron from the chlorine atom when it has a charge of −1. In this particular example, the electron binding energy has the same magnitude as the electron affinity for the
An electron in the s-sublevel is capable of shielding electrons in the p-sublevel of the same principal energy level. The size of the shielding effect is difficult to calculate precisely due to effects from quantum mechanics. As an approximation, we can estimate the effective nuclear charge on each electron by the following:
However, by removing one electron from dihelium, the stable gas-phase species He + 2 ion is formed with bond order 1/2. Another molecule that is precluded based on this principle is diberyllium. Beryllium has an electron configuration 1s 2 2s 2, so there are again two electrons in the valence level. However, the 2s can mix with the 2p orbitals ...