Question
Explain, which of the following pairs of elements would have a more negative electron gain enthalpy:
(i) N or O (ii) O or S
Solution
(i) O has more negative electron gain enthalpy than N. This is because O atom has higher nuclear charge and lower atomic size than N.
(ii) S has more negative electron gain enthalpy than O. The size of O is much smaller than that of S., As a result, the electron-electron repulsions in the smaller 2p-subshell of O are comparatively larger than those present in the bigger 3p-subshell of S. Therefore S has a higher tendency to accept an addition electron than O.
