Why are lithium salts commonly hydrated and those of the other alkali ions usually anhydrous?

Explanation

As `Li^(+)` is the smallest ion among all the alkali metal ions, it can polarise water molecules more easily than the other alkali metal ions. So, numerous water molecules get attached to lithium salts as water of crystallisation. However, this is not observed in case of other alkali metal ions. Thus, lithium salts are commonly hydrated (Example: `LiCl.2H_2O`) and those of the other alkali ions are usually anhydrous.