Mixture
A physical combination of two or more substances that keep their own chemical identities and can be present in any proportion.
Unit
Dimensionless
In depth
Because no bonds are formed or broken, the components of a mixture can be separated by physical techniques that exploit differences in boiling point, solubility, particle size or density. Mixtures have variable composition and no fixed melting or boiling point, unlike compounds.
Examples in the real world
Air, seawater, brass, milk, and a mixture of iron filings and sulfur powder that a magnet can separate.