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

(N/A) Among alkali metal ions,$Li^{+}$ has the smallest size,due to which it has a very high charge density and can easily polarize water molecules. This leads to strong ion-dipole interactions,causing $Li$ salts to be commonly hydrated (e.g.,$LiCl \cdot 2H_2O$). The other alkali metal ions $(Na^{+}, K^{+}, Rb^{+}, Cs^{+})$ are larger in size,resulting in lower charge density and a weaker ability to polarize water molecules. Consequently,their salts are usually anhydrous.