Metals and Non-metals — Definition

Definition

Metals and non-metals are broad classes of elements identified through characteristic patterns of physical and chemical behaviour. Metals commonly conduct electricity and can be shaped into sheets or wires, while many non-metals differ in these respects.

Exceptions matter: mercury is a liquid metal, graphite conducts electricity and iodine is lustrous. Chemical behaviour, including reactions and the formation of compounds, supplies further distinctions.

A classification based on one visible property is therefore unreliable. The properties of an element must also be distinguished from those of its compounds or alloys, which can behave differently from the original constituents.