The electron affinities of the following 4th row elements have the following values:
K + e - → K -1 EA = -48 kJ/moles
Ca + e - → Ca -1 EA = -4 kJ/moles
Ga + e - → Ga -1 EA = -30 kJ/moles
From the standpoint of the electron configuration of the atoms, explain this trend, in particular, why Ca is a small exothermic value.