Sulphur electron affinity

The electron affinity E of the halogens is indeed positive, but for oxygen and sulphur energy is necessary to form a two-fold negative ion, namely about 150 and 90 kcal/gr.atom. (Actually 71 and 48 keal/gr. atom respectively, are set free in the formation of O- and S ). The electron affinity of hydrogen is weakly positive 16.5 kcal/gr.atom are set free in the formation of H. ... 

For the elements oxygen and sulphur which form di-negative ions, the electron affinity values are negative. Although cnerg) is released when one extra electron is added, much more energy is required to force tlie second electron into an ionised atom. 

Sulphur, determination in thiols 301 thiol derivatives 752, 753 Sulphur atoms, electron affinity 22-24, 79, 80 energy 78... 

In the sulphides, selenides, tellurides and arsenides, all types of bond, ionic, covalent and metallic occur. The compounds of the alkali metals with sulphur, selenium and tellurium form an ionic lattice with an anti-fluorite structure and the sulphides of the alkaline earth metals form ionic lattices with a sodium chloride structure. If in MgS, GaS, SrS and BaS, the bond is assumed to be entirely ionic, the lattice energies may be calculated from equation 13.18 and from these values the affinity of sulphur for two electrons obtained by the Born-Haber cycle. The values obtained vary from —- 71 to — 80 kcals and if van der Waal s forces are considered, from 83 to -- 102 kcals. 

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