A Level Chemistry OCR Practice Exam 2025 - Free Chemistry Practice Questions and Study Guide

A hydrogen bond is characterized by a strong attraction between a hydrogen atom and a highly electronegative atom, such as fluorine, oxygen, or nitrogen. This type of bond occurs due to the differences in electronegativity; when hydrogen is covalently bonded to a highly electronegative atom, the shared electrons are pulled closer to the electronegative atom, creating a dipole. The hydrogen atom, carrying a partial positive charge, can then attract the lone pair of electrons on another electronegative atom, resulting in the formation of a hydrogen bond.

The strength of hydrogen bonding is significant compared to other types of intermolecular forces, which explains its importance in biological systems and the physical properties of compounds like water. In contrast, covalent bonds involve the sharing of electrons, ionic bonds involve the transfer of electrons between atoms, and metallic bonds involve the sharing of free electrons among a lattice of metal cations. These interactions do not describe the specific attraction mechanism of hydrogen bonds, which is distinct due to the involvement of hydrogen and highly electronegative atoms.