Biology – Water | e-Consult

Hydrogen bonding occurs between water molecules due to the polarity of the water molecule (H₂O). Oxygen is more electronegative than hydrogen, leading to a partial negative charge (δ-) on the oxygen atom and partial positive charges (δ+) on the hydrogen atoms. This allows the partially negative oxygen atom of one water molecule to be attracted to the partially positive hydrogen atom of another water molecule. This attraction is a hydrogen bond. While individually weak, the cumulative effect of numerous hydrogen bonds between water molecules results in strong intermolecular forces.

These hydrogen bonds are crucial for water's solvent properties. Water's polarity allows it to dissolve many ionic compounds and polar molecules. The δ+ ends of water molecules are attracted to the δ- ends of anions in ionic compounds, while the δ- ends are attracted to the δ+ ends of cations. This process, known as hydration, effectively surrounds the ions and weakens the ionic bonds, allowing them to disperse in the water. Similarly, water can dissolve polar molecules through dipole-dipole interactions. This solvent action is vital for biological systems because many biochemical reactions occur in aqueous solutions, and water facilitates the transport of nutrients and waste products within organisms.