What is another name for electron affinity

Electron affinity

Electron affinity, in the atom: the energy that is released when an electron is added to a neutral atom. The electron affinity describes the tendency of an element to form anions; it is decisive for the type of bond between two atoms. Atoms with a high electron affinity form ionic bonds with atoms with a low ionization energy if this results in an overall gain in energy. A classic example of this is NaCl (electron affinity of Cl: 3.71 eV, ionization energy of Na 5.14 eV, energy gain through electrostatic attraction: 4.51 eV, i.e. overall an energy gain of 3.08 eV results from the ionic bond). The electron affinity is determined by the electron configuration; it decreases in the periodic table of the elements from top right to bottom left. Halogens have the greatest electron affinities. This has to do with the fact that they reach noble gas configuration by taking up only one electron. The electron affinities of the alkali metals, on the other hand, are very low. Together with the ionization energy, the electron affinity forms the basis for calculating the electronegativity according to Pauling.In the semiconductor electron affinity is defined as the energy difference between the conduction band edge at the surface and the vacuum level.

Electron affinitiesχ different elements in electron volts [eV].

element Electron affinity χ
in eV
hydrogen 0,747
fluorine 3,45
chlorine 3,71
bromine 3,36
Iodine 3,06
oxygen 1,47
lithium 0,54
sodium 0,74


Electron affinity: Change in total energy (

) depending on the partial charge for fluorine and chlorine.