Question

Why the electron affinity of chlorine is greater than fluorine

Answer 1

The electron affinity is the energy released when an electron is added to neutral, isolated, gaseous atom in its ground state,

In the case of fluorine or oxygen or nitrogen, due to their small size of atoms, and almost filled (more than 4 valence electrons in outer second orbit), any extra added electron faces repulsion from non-bonding electrons already present in valence shell. Hence Lesser energy is released,

As compared to from their next group elements, although P, O or Cl, has same number of valence electrons, but their size of atom is greater and their valence shell is 3rd orbit which can have maximum 18 electrons(i mean they can have additional electrons without any extra repulsion