Ionization Enthalpies

Alkaline earth metal atoms are still fairly large, so their ionization enthalpies remain low by overall standards, and — as size increases down the group — ionization enthalpy falls further from Be to Ba (Table 10.2). Compared period-by-period with the alkali metals, though, Group 2's first ionization enthalpies are consistently higher, simply because the Group 2 atoms are smaller. …