Question

Give reason why chlorine has more negative electron gain enthalfy than fluorine

Answer 1

Chlorine has more negative electron gain enthalpy than fluorine, even though fluorine is more electronegative.
The reason for this is that when fluorine gains one electron, a lot of energy is spent in overcoming the electron-electron repulsions in the fluorine atom because of it’s exceptionally small size. So less energy is dissipated on accepting an electron in fluorine than in case of chlorine.