Launching your learning experience…
Detailed notes on Metals for Cambridge IGCSE Coordinated Science, covering key concepts, explanations, examples, and exam-focused revision points.
Metal uses are determined by their specific properties. Cambridge tests the property-use link for common metals (iron, copper, aluminium) and alloys (steel, brass, bronze).
Mapped to the Cambridge IGCSE 0654 syllabus (2025-2027).
Every use of a metal is justified by one or more specific properties. Always state the property AND explain how it makes the metal suitable.
| Metal/Alloy | Key properties | Uses |
|---|---|---|
| Iron | Hard, dense, strong, cheap | Construction (reinforced concrete), machinery, pipes |
| Steel | Stronger than iron, hard, magnetic | Cars, buildings, ships, tools, bridges |
| Stainless steel (Fe+Cr+Ni) | Resistant to corrosion, strong | Cutlery, surgical instruments, kitchen equipment |
| Copper | Excellent electrical conductor, ductile, good thermal conductor | Electrical wiring, water pipes, heat exchangers |
| Aluminium | Low density, resistant to corrosion (Al₂O₃ layer), malleable, ductile | Aircraft, car bodies, drink cans, cooking foil, overhead power cables |
| Titanium | High strength-to-weight ratio, resistant to corrosion, biocompatible | Jet engine parts, hip/bone implants, racing bikes |
| Brass (Cu+Zn) | Harder than copper, corrosion-resistant, attractive | Musical instruments (e.g. trumpets), door fittings |
| Bronze (Cu+Sn) | Hard, strong, corrosion-resistant | Statues, bearings, coins |
| Gold | Unreactive, malleable, excellent conductor | Jewellery, electrical contacts in electronics |
Why aluminium resists corrosion: A thin layer of Al₂O₃ forms on the surface — this is self-protective (unlike rust on iron, which flakes off and exposes more iron).
Why aluminium is used for aircraft: Low density = lightweight → less fuel needed. Resists corrosion even in rain and altitude conditions.
Verbatim phrases and definitions Cambridge mark schemes credit.
Paper 4: 'Suggest why copper is used for electrical wiring and not iron' (2 marks — copper is a better electrical conductor; copper is ductile — can be drawn into wires). 'State ONE property of aluminium that makes it suitable for use in aircraft, and explain why this property is important' (2 marks — low density; aircraft is lightweight, less fuel needed). Property-use questions are worth 1-2 marks each and appear in most papers.
Sources: Cambridge IGCSE Coordinated Sciences 0654 syllabus 2025-2027 (C10); 0654 Examiner Reports 2022-2024. Last reviewed 2026-05-14.
Step-by-step solutions to past-paper-style questions on uses of metals, written exactly the way a tutor would explain them at the board.
Question
Explain why galvanising protects iron from rusting even when the zinc coating is scratched.
Step-by-step solution
Step 1
Galvanising coats iron with a layer of zinc. Zinc is more reactive than iron and oxidises preferentially.
Step 2
If the zinc layer is scratched and iron is exposed, zinc still acts as a sacrificial anode: Zn is oxidised (loses electrons) instead of Fe.
Step 3
Electrons flow from the Zn to the Fe, keeping the Fe reduced (as Fe, not Fe²⁺/Fe³⁺); iron is cathodically protected.
Step 4
This continues until all the zinc is consumed; the iron remains protected throughout.
Answer
Zinc is more reactive; acts as sacrificial anode — Zn corrodes preferentially; electrons flow to Fe keeping it reduced; Fe protected even if Zn is scratched.
Examiner tip
Key terms: 'sacrificial protection', 'zinc is more reactive', 'zinc corrodes preferentially', 'iron protected'. All must be stated.
Question
Aluminium is used for aircraft bodies instead of steel. Give TWO reasons why.
Step-by-step solution
Step 1
Reason 1: aluminium has a much lower density than steel (~2.7 g/cm³ vs ~7.9 g/cm³); lighter aircraft → less fuel needed.
Step 2
Reason 2: aluminium forms a protective layer of aluminium oxide (Al₂O₃) on its surface, preventing further corrosion; steel rusts without protection.
Answer
Lower density (lighter) AND protective Al₂O₃ oxide layer resists corrosion.
Question
State why copper is preferred over aluminium for household electrical wiring.
Step-by-step solution
Step 1
Copper has higher electrical conductivity than aluminium (lower resistance per unit length).
Step 2
Copper is more ductile than aluminium; it can be drawn into thinner wires without breaking.
Step 3
Copper does not react with air/water at room temperature; it maintains its conductivity over many years.
Answer
Copper has higher conductivity (lower resistance) than aluminium, and is more ductile and more corrosion-resistant for household wiring.
Question
Describe an experiment to show that BOTH oxygen and water are needed for iron to rust.
Step-by-step solution
Step 1
Set up three test tubes, each containing an iron nail: Test 1 — dry air only (add anhydrous calcium chloride to remove water); Test 2 — boiled distilled water only (remove dissolved air, seal with oil); Test 3 — ordinary air and water present.
Step 2
Leave all three for several days. Observe.
Step 3
Result: only the nail in Test 3 (air + water) rusts. Tests 1 and 2 show no rusting.
Step 4
Conclusion: both oxygen (from air) AND water are required simultaneously for rusting.
Answer
Three nails: (1) dry air — no rust; (2) boiled water sealed from air — no rust; (3) air + water — rusts. Conclusion: both O₂ and H₂O are needed.
Definitions to memorise and the exact keywords mark schemes credit for uses of metals answers — sharpened from recent examiner reports for the 2026 0654 sitting.
The corrosion of iron or steel in the presence of both oxygen and water to form hydrated iron(III) oxide (rust, Fe₂O₃·xH₂O); requires both O₂ and H₂O simultaneously.
Coating iron or steel with a layer of zinc to prevent rusting; the zinc provides both a physical barrier and sacrificial protection if the coating is damaged.
Attaching a more reactive metal (Zn or Mg) to iron; the more reactive metal is preferentially oxidised (corrodes) instead of iron, protecting the iron structure.
Electrochemically thickening the natural Al₂O₃ layer on aluminium by making it the anode in an electrolytic cell; provides a thicker, more durable protective oxide layer.
Using electrolysis to deposit a thin layer of a metal (e.g. chromium, silver, gold) onto an object to improve appearance, prevent corrosion, or reduce wear.
The traps other students keep falling into on uses of metals questions — taken from recent Cambridge IGCSE 0654 examiner reports and mark schemes — and how to avoid them.
0654 Examiner Report 2022
Why it happens
Students see rust outdoors and associate it only with air exposure.
How to avoid it
Rusting requires BOTH oxygen AND water simultaneously. Iron in dry air or in boiled, sealed water does not rust.
Why it happens
Students see the zinc layer as simply covering the iron and miss the electrochemical mechanism.
How to avoid it
Galvanising also provides sacrificial protection: even if the zinc layer is scratched/broken, Zn corrodes preferentially instead of Fe.
Why it happens
Students see aluminium high in the reactivity series and expect it to corrode rapidly.
How to avoid it
Aluminium is reactive but self-protecting: it rapidly forms a thin, impervious Al₂O₃ layer that prevents further oxidation. This explains why aircraft (Al) don't corrode like iron.
The things students keep getting wrong in this sub-topic, answered.