Elements of group 16 generally show lower value of first ionization enthalpy compared to the corresponding elements of group 15. Why ?

Explanation

This is because of the following two reasons : (i) Due to extra stability of the exactly half-filled electronic configuration of p-orbitals of group 15 elements, they require larger amount of energy to remove an electron as compred to those of group 16 elements.
(ii) After removal of an electron, the group 16 elements yield species which have more stable exactly half-filled electronic comfiguration of p-orbitals while this is not so in case of group 15 elements.