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Learn5070Paper 1 · Multiple ChoiceMetalsProperties, uses and alloys
Metals · Subtopic 1 of 4

Properties of Metals and Alloys

Metals are usually shiny, dense, malleable, ductile, good conductors of heat and electricity, and have high melting points. Many react with oxygen, water and dilute acids. An alloy is a mixture of a metal with other elements. The different-sized atoms disrupt the regular layers, so they can't slide easily: alloys are harder and stronger than pure metals. Examples: steel (iron + carbon), stainless steel (+ chromium, nickel), brass (copper + zinc).

Cambridge 5070 Paper 1Cambridge 5070 Paper 2Cambridge 0620 Papers 2, 4Cambridge 0620 Papers 1, 3Edexcel 4CH1 Paper 1CEdexcel 4CH1 Paper 2C≈ 30 minRevision 1 · updated 2026-10-30
Section 1 of 14

Learning objectives

  • Describe the properties of metals.
  • Relate uses of metals to their properties.
  • Explain why alloys are harder than pure metals.
Pause and think

Pure gold is so soft you can dent it with a fingernail. Why is most jewellery 18-carat rather than 24-carat?

Section 2 of 14

Core idea

Start hereWhy not pure gold coins?

Pure gold coins would wear smooth in a few years of handling. Mints add copper to make them hard. Mixing metals changes everything about how they behave.

The big idea

Metallic bonding gives metals their typical properties. Adding atoms of a different size makes an alloy, in which the layers can't slide as easily, so it is harder and stronger.

1. Properties and uses

Worked exampleMatching metals to jobs

Choose a metal for (a) overhead power cables and (b) a bridge.

Goal
Justify each choice.
Strategy
Match properties to the job.
  1. (a) aluminium (with steel core)\text{(a) aluminium (with steel core)}
    Good conductor, low density so less weight on pylons, resists corrosion.
  2. (b) steel\text{(b) steel}
    Very strong, relatively cheap; painted to prevent rust.
AnswerAluminium for cables; steel for bridges.
✓ CheckCopper conducts better but is far denser and more expensive ✓.

2. Alloys

Why alloys are harder

Larger atoms block the slip planes.

Key takeawayCommon alloys Mild steel (Fe + C); stainless steel (Fe + Cr + Ni); brass (Cu + Zn); bronze (Cu + Sn); duralumin (Al + Cu + Mg).
Pause and think

Why does an alloy usually melt over a range of temperatures?

Summary

  • Uses follow properties.
  • Alloys are mixtures.
  • Different atoms stop layers sliding.
Key words
Alloy
A mixture of a metal with other elements.
Ductile
Can be drawn into wires.
Malleable
Can be hammered into shape.
HistoryThe Bronze Age. Around 3300 BC people discovered that adding tin to copper made bronze, much harder than either metal. It was so important that a whole age of history is named after it.
Fun factMemory metal. Nitinol, an alloy of nickel and titanium, "remembers" its shape: bent glasses frames spring back when warmed.
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