Chemistry Question on Classification of elements & periodicity in properties

Question

Which of the following element has highest ionization energy?

Answer 1

Solution

Though ionisation energy, generally increases from left to right in a period, but elements of II A and V A groups have higher ionisation than corresponding III A and VI A group elements (true upto IVth period). The reason is their comparatively stabler electronic configuration ( $n{{s}^{2}}$ and $n{{s}^{2}}n{{p}^{3}}$ respectively.) Hence, in the light of above discussion, we can conclude that ionisation potential of phosphorus should be the highest among given element and it is found so $I{{E}_{1}}$ for P= 1012 kJ $\text{mo}{{\text{l}}^{-1}}$ $I{{E}_{1}}$ for S = 999 kJ $\text{mo}{{\text{l}}^{-1}}$