Li-salts are commonly hydrated while other alkali metal salts are usually anhydrous. Explain.

Explanation

Due to the smallest size among all alkali metal ions, `Li^(+)` ion can interact with water molecules more easily than the other alkali metal ions. Hence the salts of lithium are commonly hydrated. On the other hand, other alkali metal ions being larger in size have little tendency to get hydrated. Therefore, their salts are generally anhydrous. For example, lithium chloride crystallises as `LiCl. 2H_2O` but sodium chloride crystallises as NaCl.