Discuss the hydration of water

A water molecule (H₂O) has a bent shape. The oxygen atom is more electronegative than the hydrogen atoms, pulling electron density towards itself. This creates a partial negative charge (δ⁻) on the oxygen atom and partial positive charges (δ⁺) on the hydrogen atoms.

When an ionic compound dissolves in water, the polar water molecules orient themselves around the ions. The partially negative oxygen atoms of water molecules are attracted to positive ions (cations), and the partially positive hydrogen atoms are attracted to negative ions (anions).

This surrounding of ions by water molecules is called a hydration shell. It stabilizes the ions in solution, preventing them from recombining and allowing the ionic compound to dissolve. For example, when NaCl dissolves, Na⁺ ions are surrounded by the oxygen ends of water molecules, and Cl⁻ ions are surrounded by the hydrogen ends.

Water can also hydrate non-ionic polar molecules or molecules with polar functional groups, such as alcohols or sugars, through hydrogen bonding. This process also involves the formation of intermolecular attractions between water and the solute.