Cambridge IGCSE Chemistry · Syllabus 0620 · Metals
Reactivity Series
What is Reactivity Series?
An order of metals arranged by how readily each one reacts, with the most reactive at the top. Carbon and hydrogen are included as non-metal reference points: carbon marks the boundary for extraction method and hydrogen marks the boundary for reaction with dilute acids.
This definition is part of the Metals chapter in Cambridge IGCSE Chemistry.
Reactivity Series in context
Everything in Topic 9 hangs on one chain. A metal is a lattice of positive ions in a sea of delocalised electrons, and that structure gives the physical properties. Those properties decide what each metal is used for. Separately, metals can be put in order of how readily they react — the reactivity series — and that one position predicts a metal’s reactions with water, steam and acid, whether it can protect iron from rusting, and how hard it is to pull out of its ore. Extended candidates add a second layer to the same chain: reactivity is the tendency of an atom to form a positive ion, and that is what displacement reactions and sacrificial protection actually measure.
Common mistakes with Reactivity Series
- 6. “Aluminium does not react with water, so it must be low in the reactivity series.” Supplement 9.4.5 Repair Aluminium is high in the series, above zinc and iron. It behaves as though it were unreactive because a thin, tough, continuous layer of aluminium oxide forms on the surface and stops air and water reaching the metal. Say “oxide layer”, never “low reactivity”. Where Lesson 9.4F. Supplement 9.4.5
- 8. “Aluminium is used for drinks cans because it is unreactive.” Core 9.2.1 Defect Contradicts subtopic 9.4, where aluminium is above zinc and iron. Reason Resisting corrosion and being unreactive are not the same claim. Aluminium is high in the series and still resists corrosion. Repair “Aluminium resists corrosion, so the food acids do not attack it.” That is the whole Core answer. Transfer Which subtopic does the claim contradict? 9.4 — the reactivity series, where aluminium sits above zinc and iron. Extended Supplement 9.4.5 Extended candidates can also give the reason: a thin, tough, continuous oxide layer keeps air, water and acids off the metal. Core candidates are not asked for it.
- 15. “Copper does not react with dilute acid because it has a protective oxide layer.” Core 9.4.2 Defect Borrows aluminium’s explanation for a metal that does not need one. Reason Copper genuinely is unreactive towards dilute acid, because it sits below hydrogen. No barrier is involved. Repair “Copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from the acid.” Transfer Which metal does need the oxide-layer explanation, and why? Aluminium — because its position predicts a reaction that is not observed.
Examiner tips on Reactivity Series
- How to write a no-reaction answer. “Nothing happens” is not an answer. “No reaction, because copper is below hydrogen in the reactivity series, so it cannot displace hydrogen from the acid” is. The reason is the answer; the observation is only the evidence.
- If a session goes badly. Do not restart the chapter. Identify which statement failed — the mastery checklist gives you the code and the official reference — and re-read only the lesson that owns it. Topic 9 is unusually well suited to this, because almost every failure traces back to one specific position in the reactivity series.
- If you are on the Core route and short of time, the highest-value 20 minutes in this chapter is the reactivity series plus R32–R50: those prompts carry three Core statements between them — the named reactions, the deduction skill, and the series itself — and they feed straight into 9.5 and 9.6.