Which of the elements Na, Mg, Si and P have the greatest difference between first and second ionization enthalpies? Briefly explain your answer.

Explanation

Among these elements, Na, is an alkali metal and has only one electron in its valence shell `(3s^(1)).` Therefore, its `IE_(1)` is very low. After the removal of one electron, it acquires neon gas configuration i.e., `(1s ^(2) 2s ^(2) 2p ^(6)).` Therefore, its `IE_(2)` is expected to be very high. Consequently, the difference in first and second inonization enthalpies would be greatest in case of Na.