`IE_2` values of alkaline earth metals are much smaller than those of alkali metals. Explain.

Explanation

(i) Although `IE_1` values of alkaline earth metals are higher than that of alkali metals, the `IF_2` values of alkaline earth metals are much smaller than those of alkali metals.
(ii) This occurs because in alkali metals the second electron is to be removed from a cation, which has already acquired a noble gas configuration
(iii) In the case of alkaline earth metals the second electron is to be removed from a monovalent cation, which still has one electron in the outermost shell.
(iv) Thus, the second electron can be removed more easily in the case of group 2 elements than in group 1 elements.