The crystalline salts of alkaline earth metals contain more water of crystallisation than the corresponding alkali metal salts. Why ?

Explanation

Alkaline earth metals have smaller size and higher nuclear charge than alkali metals. Therefore, alkaline earth metals have a higher tendency to attract water molecules and hence contain more water of crystallisation molecules than alkali metals. For example,` MgCl_2.6H_2O`. However, among alkali metals only lithium because of its small size forms hydrated salts such as `LiCl.2H_2O`.