Question

What is electron affinity and how it depends on atomic size, effective nuclear change and screening factor?

Answer 1

$e^{-}$ affinity is the amount of energy required to add a $e^{-}$.

$e^{-}$ affinity value increases with effective nuclear charge. With the increase in effective nuclear charge, attraction increases thereby increasing $e^{-}$ affinity. Also, as screening/shielding effect increases, electron affinity decreases as the incoming $e^{-}$ has not much attraction with the nucleus.