Delocalised Electron

Summary: An electron that is not associated with any specific atom or bond but is free to move throughout a structure. Tags: igcse chemistry definition bonding metals Created: 2026-07-14 Last Updated: 2026-07-14

A delocalised electron is an electron that is not bound to a single atom or covalent bond but is free to move throughout an extended structure. In metallic bonding, the outer-shell electrons of metal atoms become delocalised, forming a mobile ‘sea’ of electrons that surrounds a lattice of positive metal ions and holds it together through strong electrostatic attraction. This electron mobility explains why metals conduct electricity and heat so effectively, and why they are malleable and ductile — the electron sea can reform around ions as they slide past one another. Delocalised electrons also occur in graphite, where one electron per carbon atom is free to move between the hexagonal carbon layers, giving graphite its electrical conductivity along the planes. For IGCSE exams, you must be able to explain that the delocalisation of outer-shell electrons is the defining feature of metallic bonding and is what distinguishes the properties of metals and graphite from those of other giant structures.

Key term — IGCSE Chemistry (0620/0971) glossary.