(i) Ionisation enthalpy: The first ionisation enthalpies of alkaline earth metals are higher than those) of alkali metal because of increased nuclear charge, However 2nd ionisation enthalpies of alkaline earth metals are lower than those of corresponding alkali metals.
i.e., 1st ionisation enthalpy of Be > Li
Mg > Na and so on. ;
(ii) Basicity of oxides: The oxides of alakline earth metals are less basic as compared to the corresponding oxides of alkali metals. Because of increased nuclear charge their ionisation enthalpies are higher.
(iii) Solubilities of hydroxides : Alkaline earth metal hydroxides are less soluble in water as compared to the alkali metal hydroxides