Question

Which out of F or Cl has more negative electron gain enthalpy and why?

Answer 1

electron gain enthalpy of Cl is greater than F because F has small size, electron density increases around the nucleus and incoming electron suffers more repulsion.
in case of Cl- it has comparatively large size ,e electron density dec around the nucleus

Answer 2

Answer:

Due to its small size, the electron–electron repulsions in the relatively compact 2p-sub-shell are comparatively large, and hence, the incoming electron is not accepted with the same ease as is the case with larger Cl atom. Consequently, electron gain enthalpy of Cl is more negative than that of F.