Key Stage 3 science · Chemistry – Materials

KS3 reactivity series and materials: a guide for parents

Metals can be put in order of how readily they react, and that order, the reactivity series, explains how each metal is extracted from its ore. In Years 7 to 9 children also compare the properties of ceramics, polymers and composites and link them to how those materials are used.

Reactivity series and materials, explained

Pupils compare how different metals react with oxygen, water and dilute acid, and with each other. Potassium and sodium react violently, magnesium burns brightly, iron rusts slowly and gold hardly reacts at all. Putting the metals in order gives the reactivity series. A common version used in schools runs from most reactive to least: potassium, sodium, lithium, calcium, magnesium, aluminium, carbon, zinc, iron, copper, silver, gold. Carbon is not a metal, but it is included because it is a useful reference point.

The series predicts displacement reactions: a more reactive metal pushes a less reactive metal out of its compound. Magnesium will take the place of copper in copper sulfate, but copper will not take the place of magnesium. It also explains how metals are obtained. Most metals are found in rocks called ores, combined with other elements, often oxygen, and only unreactive metals such as gold are often found uncombined. To extract a metal from its oxide, a more reactive element must take the oxygen away. Carbon can do this for the metals below it in the series, so iron oxide and copper oxide can be heated with carbon to make iron or copper plus carbon dioxide. Removing oxygen from a compound like this is called reduction. Metals above carbon, such as aluminium, hold on to oxygen too tightly and need other, more energy-hungry methods that pupils meet at GCSE.

Aluminium is a good talking point. It sits high in the series, yet aluminium foil and cans last for years. The reason is a thin, tough layer of aluminium oxide that forms instantly in air and protects the metal underneath. High reactivity and quick corrosion are therefore not the same thing.

Pupils also study three classes of material in a qualitative way. Ceramics, such as bricks, pottery and tiles, are made by firing clay at high temperatures. They are hard, brittle, resist heat and are poor conductors, which is why they are used for mugs, bathroom fittings and furnace linings. Polymers are made of very long molecules and include plastics such as polythene as well as rubber and nylon; they are usually light, flexible, waterproof and good insulators, but many do not rot away. Composites combine two or more materials to get properties that neither has alone, such as reinforced concrete (steel rods in concrete), glass-reinforced plastic and carbon fibre.

Words your child will hear

Reactivity series: A list of metals in order of how readily they react, from most reactive to least reactive.
Ore: A rock that contains enough of a metal compound to make it worth extracting.
Displacement: When a more reactive element takes the place of a less reactive one in a compound.
Ceramic: A hard, brittle, heat-resistant material such as brick or pottery, usually made by firing clay.
Reduction: Removing oxygen from a compound, as when carbon takes the oxygen from copper oxide.
Polymer: A material made of very long chain-like molecules, such as polythene, nylon and rubber.
Composite: A material made by combining two or more materials to give better properties.
Corrosion: The slow wearing away of a metal by reacting with substances in its surroundings, such as rusting.

What the National Curriculum says

The programme of study for Key Stage 3 says:

Pupils should be taught about the order of metals and carbon in the reactivity series
Pupils should be taught about the use of carbon in obtaining metals from metal oxides
Pupils should be taught about properties of ceramics, polymers and composites (qualitative)

Objectives from the National Curriculum in England, © Crown copyright, used under the Open Government Licence v3.0.

A worked example

Which of these oxides can be turned into a metal by heating with carbon: copper oxide, iron oxide, aluminium oxide? Write the word equation for one that works.

Place carbon in the reactivity series. Carbon sits between aluminium and zinc.
```
aluminium
carbon
zinc
iron
copper
```
Apply the rule. Carbon can only take oxygen from the oxide of a metal that is less reactive than carbon. Metals below carbon in the series are less reactive.
Check each metal. Copper is below carbon, so heating copper oxide with carbon works. Iron is also below carbon, so iron oxide works. Aluminium is above carbon, so carbon is not reactive enough to remove its oxygen.
Write the word equation for copper. Carbon takes the oxygen and becomes carbon dioxide, leaving the copper metal.
```
copper oxide + carbon
→ copper + carbon dioxide
```
What you would see: black copper oxide powder changes to a pink-brown solid, and the gas given off turns limewater cloudy.

Copper oxide and iron oxide can both be reduced by carbon. Aluminium oxide cannot, because aluminium is more reactive than carbon.

Common mistakes and how to help

Thinking a reactive metal must be strong or hard

Reactive suggests energy and strength, and metals are generally thought of as tough materials.

What helps: Compare sodium and gold. Sodium is soft enough to cut with a knife but reacts violently with water. Gold is soft too, but it is almost unreactive. Reactivity measures how readily the atoms react, not how tough the metal is.

Assuming aluminium is an unreactive metal because it does not rust

Aluminium cans and window frames stay shiny for years, so it looks inert.

What helps: Explain the oxide layer. Aluminium reacts with oxygen immediately, but the thin layer it forms stops further reaction. Even a freshly scratched surface forms a new layer within moments.

Believing that all metals rust

“Rust” is used loosely for any corrosion.

What helps: Rusting is the name for iron (and steel) reacting with water and oxygen to form iron oxide. Copper goes green, silver goes dark and gold does not change.

Thinking a composite is just a mixture, or that ceramics means only pottery

The everyday words are used loosely, and “combined” sounds like “mixed”.

What helps: In a composite, each material stays distinct but they are bonded together so that the result is stronger or lighter than either on its own, as with steel rods in concrete. Ceramics include bricks, tiles and bathroom fittings as well as plates and mugs.

How to help at home

Rust trial. Put identical plain steel nails (not galvanised ones) in three jars: one with tap water, one with salty water and one dry. Look at them each day for two weeks. Ask what rust needs and how paint, oil or a coat of zinc (galvanising) could protect iron.
Magnet sort. Test a magnet on a collection of food and drink cans, foil, cutlery and coins. Steel cans stick and aluminium ones do not, which is how recycling plants separate them. Ask what steel contains that makes it magnetic.
Material hunt. Find a ceramic, a polymer, a metal and a composite in the kitchen or bathroom. A mug, a plastic bottle, a saucepan and a plywood shelf made of glued layers make a good start. Ask which properties make each suited to the job.
Compare flexibility. Gently flex strips of plastic and cardboard, and tap a mug and a plastic cup to listen to the sound. Do not drop or break anything. Ask which is brittle, which is flexible, and why oven dishes are usually ceramic or glass rather than plastic.
Follow the can. Find out what happens to aluminium drinks cans after recycling. Ask your child why using recycled aluminium needs far less energy than extracting new metal from ore.

Everything in Key Stage 3 science

Updated 20 October 2026.