10.3Unit 5: Metals, non-metals, acids and alkalis

Metal mixtures

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Lesson summary

10.3 Metal mixtures — CHECKPOINT (CHEMISTRY) notes: Describe alloys and explain why they differ from pure metals.Alloy = a mixture of metals, made by mixing different metals and melting themAtoms — the atoms of the different metals mix but do not bond togetherProperties — differ …

Melting point
Properties — differ from those of the metals in the alloyBronze, copper plus tin, is harder than either metal
Pure metal — atoms are the same size in regular rows, and layers slide over each other easily
Alloy — a different-sized atom disrupts the regular patternThe layers cannot slide as easily
The alloy is harder and stronger than the pure metal
Saying an alloy is a compound — it is a mixture

Part 1 of 4What is an alloy

1Alloy

= a mixture of metals, made by mixing different metals and melting them

2Atoms

— the atoms of the different metals mix but do not bond together

3Properties1 point

— differ from those of the metals in the alloy

Bronze, copper plus tin, is harder than either metal.

4Steel1 point

— an alloy of iron and carbon, much harder than pure iron

With chromium and nickel it does not rust and is used for cutlery.

Part 2 of 4Why alloys are harder

Pure metal — atoms are the same size in regular rows, and layers slide over each other easily
Alloy — a different-sized atom disrupts the regular pattern
- The layers cannot slide as easily.
- The alloy is harder and stronger than the pure metal.

Part 3 of 4Uses of alloys

Alloy	Made from	Use
Coins	Copper and nickel (silver-coloured); copper, zinc and tin (copper-coloured)	Hardwearing but malleable enough to stamp
Gold jewellery	Gold and copper (18 carat: 18 parts of 24 gold)	Stronger than pure gold
Duralumin	Aluminium, magnesium and copper	Aeroplanes; about five times stronger than aluminium
Titanium alloys	Titanium with other metals	Artificial joints
Nitinol	Nickel and titanium	Shape memory glasses frames

Part 4 of 4Brass and bronze

Alloy	Made from	Properties and uses
Brass	Copper and zinc	Golden, resistant to corrosion; musical instruments, plumbing
Bronze	Copper and tin	Hard, corrosion resistant; sculptures, bells, cymbals, ship fittings

Melting point — alloys melt over a range because the proportions of metals vary

Last updated: 12 October 2026

Part 1 of 4What is an alloy

Part 2 of 4Why alloys are harder

Part 3 of 4Uses of alloys

Part 4 of 4Brass and bronze

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