Estimated Electron Affinities of the Light Elements

Abstract

The electron affinities of the light elements have been estimated by an empirical method of extrapolation. The ionization potentials ($I$) of isoelectronic systems are considered to be parabolic functions of the atomic number ($Z$). The Moseley curves ${I}^{\frac{1}{2}}:Z$ of the first ionization potential of the electronic systems containing from one to eighteen electrons have been completed. They are nearly straight lines except in their lower extremities where they show a bending towards the axis of atomic number $Z$. Wherever a check was possible it is found that the estimated electron affinities agree with experiment or with other calculation as obtained from wave mechanics or from thermochemical considerations by means of a Born-Haber cycle. The estimated electron affinities (in electron-volts) are: H (+0.7), He (-0.5), Li (+0.3), Be (-0.6), B (+0.1), C (+1.37), N (+0.04), O (+3.8), F (+3.9), Ne (-1.20), Na (+0.1), Mg (-0.9), Al (-0.2), Si (+0.6), P (+0.2), S (+2.1), Cl (+3.7), A (-1.0), Ni (+0.3), Cu (+1.2), Ag (+1.0), Hg (+1.8).