Water (H₂O) is a polar molecule, meaning it has an uneven distribution of electrical charge across its structure. This happens because the oxygen atom is more electronegative than the hydrogen atoms—it pulls the shared electrons in the covalent bonds closer to itself. As a result, the oxygen end of the molecule gains a slight negative charge, while the hydrogen ends become slightly positive.
This polarity allows water molecules to form hydrogen bonds with each other and with other polar substances. When water comes into contact with ionic or polar compounds, it surrounds and separates the individual ions or molecules, effectively dissolving them. This makes water an excellent universal solvent, able to dissolve salts, sugars, acids, gases like oxygen and carbon dioxide, and many other substances.
These unique interactions also explain water’s high surface tension, high specific heat, and its critical role in biological processes such as nutrient transport and cellular chemistry. Polarity is thus central to understanding why water behaves the way it does in both nature and life.