Question

Which of the following element has highest ionization energy?

• A. P
• B. S
• C. Mg
• D. Al

Answer 1

Answer: (A)

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 $\text{mo}{\text{l}}^{-1}$