Answer to Question #21476 in Inorganic Chemistry for DUBEM

Question

2 The second ionization energy of alkaline earth metals is less than that of corresponding alkali metals because--------

the alkaline earth metals have higher nuclear charge and are smaller in size
the alkali metals have no nuclear charge

of stability of a closed shell configuration

the alkali metals have higher nuclear charge and are smaller in size

Answer 1

Members of group II in comparison have higher ionization energies values than group I.This is because of group II elements smaller size with the electrons getting more attracted towards the nucleus of the atoms. This also results in less electropositive than alkali members. Although IE 1 values of alkaline Earth metals are higher than that of alkali metals, the alkaline Earth metals IE 2 values are much smaller compared to alkali metals. In alkaline Earth metals, the second electron has to be removed from the monovalent cation, which has one balance electron in the outermost shell. So, in case of group II elements the second electron could be removed with much more ease in comparison to group I elements.