Hydrogen bonds are weak attractive forces between molecules, where a slightly positive hydrogen atom on one molecule is attracted to a slightly negative electronegative atom (like oxygen, nitrogen, or fluorine) on another molecule or another part of the same molecule. They are weaker than covalent or ionic bonds but stronger than ordinary van der Waals forces, and they play a crucial role in the behavior of water, DNA, and proteins.

What hydrogen bonds are

  • A hydrogen bond forms when hydrogen is covalently bonded to a highly electronegative atom (commonly O, N, or F), which pulls electron density away and leaves the hydrogen partially positive.
  • This partially positive hydrogen is then attracted to a lone electron pair on another electronegative atom (often O, N, or F) acting as a hydrogen‑bond acceptor.

How they compare to other bonds

  • Hydrogen bonds are intermolecular (between molecules) or intramolecular (within one large molecule), whereas covalent and ionic bonds hold atoms together inside a molecule or crystal.
  • Their strength lies between strong covalent/ionic bonds and weaker dispersion forces, making them easy to break and reform, which is important in dynamic biological processes.

Everyday examples (water, DNA, proteins)

  • In water, each molecule can form multiple hydrogen bonds, creating a network that makes water liquid over a wider temperature range and gives it high boiling point, surface tension, and heat capacity.
  • In DNA, hydrogen bonds between complementary base pairs (A–T and G–C) stabilize the famous double helix without making it too rigid to unzip during replication.
  • In proteins, patterns of hydrogen bonds help form α‑helices and β‑sheets, which are key to a protein’s three‑dimensional shape and function.

Why hydrogen bonds matter now

  • Understanding hydrogen bonds is central in modern chemistry and biochemistry research, from drug–target interactions to the design of new materials and solvents.
  • Current discussions in chemistry still refine the formal definition of the hydrogen bond, recognizing that it has partial covalent character and is not purely electrostatic, as highlighted by IUPAC recommendations.

Information gathered from public forums or data available on the internet and portrayed here.