I am having trouble wrapping my head around electron affinities. And the textbook explanations aren't very helpful.
So, the textbook says that the 1st electron affinity is generally exothermic. The reason given is that the electron added is strongly attracted by the effective nuclear charge. In contrast, the successive electron affinities are always endothermic. This is due to the additional energy needed to overcome electrostatic repulsion.
This leaves me wondering:
Why is so much energy released when an electron is added to a neutral atom? I understand that the more energy released, the more stable the product is, but why does it become more stable? And why is this seemingly independent of electronic configuration?
Why isn't the attraction between the electron and the nucleus a factor in the subsequent electron affinities? In the 1st electron affinity, the atom is neutral, and yet there is still attraction between the electron and the nucleus. In successive electron affinities, the ion is negatively charged, but won't there still be attraction?
Isn't there also repulsion to overcome in the 1st electron affinity? Sure, the atom is neutral, but won't the added electron be repelled by the valence shell electrons or something?