Alloy

Summary: A mixture of a metal with one or more other elements (usually metals). Alloys are harder/stronger than pure metals. Tags: igcse chemistry definition metals Created: 2026-07-14 Last Updated: 2026-07-14

An alloy is a homogeneous mixture of a metal with one or more other elements, typically other metals or carbon, formed by mixing the components in their molten state and allowing the mixture to cool and solidify. The defining structural feature of an alloy is that atoms of the added element are a different size from those of the main metal, and when they occupy positions in the metallic lattice they disrupt the regular, orderly arrangement of atoms. This disruption prevents the layers of atoms from sliding over each other easily when a force is applied, which is why alloys are significantly harder, stronger, and less malleable than pure metals. Common IGCSE examples include: steel (iron with up to about 2% carbon, used in construction and car bodies), stainless steel (iron with chromium and nickel, resistant to rust), brass (copper with zinc, used for musical instruments and plumbing fittings), and bronze (copper with tin, used for statues and medals). On IGCSE exams, the most frequently tested concept is explaining why alloys are harder than pure metals by describing the disruption of the regular lattice structure by atoms of different sizes, often accompanied by a diagram showing the regular layers of a pure metal versus the distorted layers of an alloy.

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