(Favorable means how exothermic a reaction is, more favorable= more exothermic)
There are some abnormalities in the trends of how favorable the electron affinity is.
From Al to Cl, the Electronegativity is increasing, but the energy releasing from the electron affinity of P is smaller than that of Si. Why? Is it because of how the electrons are arranged?
There are many determinants of how favorable electron affinity is. For example, oxygen and sulfur. Generally, we will think oxygen to have a more favorable electron affinity, due to its stronger electronegativity. Both have the same electrons config, except for the number of shells. But sulfur appears to have a more favorable electron affinity because of its larger size. The smaller size of oxygen atom produces more electron-electron repulsion when one or more electrons are added.
All I ask for is a list of determinants. I tried to find one but couldn't.