Question

The lowest first ionization energy would be associated with which of the following electronic configurations

• A. 1$s^2$ 2$s^2$ 2$p^6$ 3$s^1$
• B. 1$s^2$ 2$s^2$ 2$p^5$
• C. 1$s^2$ 2$s^2$ 2$p^6$
• D. 1$s^2$ 2$s^2$ 2$p^6$ 3$s^2$ 3$p^2$

Answer 1

The correct option is A

1$s^2$ 2$s^2$ 2$p^6$ 3$s^1$

Among elements of same period (a & d) ; alkali

metal (a) have least ionization energy due to larger atomic size. b and c belong to II period element. II period

elements have more I.e than III period elements.

Order of I.E. a<d<b<c