Question

Define electron gain enthalpy and Electronegativity and How it varies along the groups and periods ?

Answer 1

Electron affinity is the amount of energy released during the conversion of a neutral isolated gaseous atom into a negatively charged ion by the addition of electrons.
Electronegativity is the subjective property of electron affinity. It is the tendency of an atom to attract the shared pair of electrons towards itself. Both increases across a period and decreases down a group