Elements of Group 16 generally show lower value of first ionisation enthalpy compared to the corresponding periods of group 15. Why?

Explanation

General outer electronic configuration of Group 15 elements is `ns^2 np^3` and that of Group 16 elements is `ns^2 np^4`. Due to extra stable half filled p-orbitals in the electronic configurations of Group elements, larger amount of energy is required electrons, compared to Group 16 elements.