Arrange the elements N, P, O and S in the order of-
(i) increasing first ionisation enthalpy.
(ii) increasing non-metallic character.
Give the reason for the arrangement assigned.
Arrange the elements N, P, O and S in the order of-
(i) increasing first ionisation enthalpy.
(ii) increasing non-metallic character.
Give the reason for the arrangement assigned.

(i) The ascending order of the initial ionization enthalpy is S< P< O< N.

The ionization enthalpy drops as we move down the group and increases as we move along the period, but in the case of oxygen and nitrogen, due to the half-filled stability of the 2 p orbitals of nitrogen, it has a larger ionization enthalpy than oxygen.

(ii) The ascending order of non-metallic nature is P<S<N<O.

The non-metallic property of the group reduces when the effective nuclear charge on the outermost shell lowers, allowing one electron to be gained. As we move across the period, the effective nuclear charge rises, increasing the nonmetallic nature.