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Detailed notes on Metals for Cambridge IGCSE Coordinated Science, covering key concepts, explanations, examples, and exam-focused revision points.
The reactivity series ranks metals by their tendency to lose electrons. Cambridge tests displacement reactions (used to determine the series), reactions with water and acid, and the link to extraction methods.
Mapped to the Cambridge IGCSE 0654 syllabus (2025-2027).
The reactivity series orders metals by their tendency to lose electrons and form positive ions. More reactive metals displace less reactive ones.
Reactivity series (most reactive at top):
K > Na > Li > Ca > Mg > Al > C > Zn > Fe > H > Cu > Ag > Au
(C = carbon; H = hydrogen — included for comparison)
Reactions with cold water:
Reactions with dilute acid (dilute HCl or H₂SO₄):
Displacement reactions: A more reactive metal displaces a less reactive metal from a salt solution.
Fe + CuSO₄ → FeSO₄ + Cu (iron is above copper → displaces it) Cu + FeSO₄ → no reaction (copper is below iron)
Explaining reactivity: The higher in the series, the easier the metal loses electrons (ionisation energy decreasing down real trends). K⁺ formation most favourable; Au⁺ formation very unfavourable.
The position of a metal in the reactivity series determines how it is extracted from its ore.
The more reactive a metal, the more stable its compounds → more energy needed to extract it.
| Position in series | Extraction method |
|---|---|
| Very reactive (K, Na, Li, Ca, Al, Mg) | Electrolysis of molten ore — very high energy cost |
| Moderately reactive (Zn, Fe, Pb) | Reduction with carbon (coke) in a blast furnace |
| Below carbon (Cu, Ag, Au, Pt) | Thermal decomposition or found native (as pure metal); some by reduction |
Blast furnace — extraction of iron:
Fe₂O₃ + 3CO → 2Fe + 3CO₂ (reduction of iron(III) oxide with carbon monoxide) C + CO₂ → 2CO (carbon dioxide reduced by more carbon)
Aluminium extraction (despite Al being less reactive than Na, it needs electrolysis because its oxide has too high a melting point to be reduced cheaply by carbon — electrolysis of molten Al₂O₃ in cryolite).
Verbatim phrases and definitions Cambridge mark schemes credit.
Paper 4: 'Zinc is added to copper sulfate solution. State two observations and write an equation' (3 marks — blue colour fades, pink/copper solid forms, Zn + CuSO₄ → ZnSO₄ + Cu). 'Explain why aluminium is extracted by electrolysis but iron is extracted by reduction with carbon' (3 marks — Al more reactive, Al₂O₃ has very high MP; Fe less reactive, can be reduced by C at feasible temperatures). Reactivity series questions are in virtually every Paper 4.
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 reactivity series , written exactly the way a tutor would explain them at the board.
Question
A piece of zinc is added to copper sulfate solution. Describe what is observed and write a balanced equation.
Step-by-step solution
Step 1
Zinc is more reactive than copper; zinc displaces copper from the copper sulfate solution.
Zn+CuSO4→ZnSO4+Cu
Step 2
Observations: the blue colour of the copper sulfate solution fades/becomes colourless (Cu²⁺ removed); a reddish-brown/copper-coloured solid deposits on the zinc.
Step 3
Zinc dissolves (the zinc surface corrodes); the solution becomes zinc sulfate (colourless).
Answer
Blue solution fades; copper deposits on zinc; Zn+CuSO4→ZnSO4+Cu.
Examiner tip
Both the observation (blue → colourless; copper deposit) and the equation are needed for full marks.
Question
Use the following observations to arrange Mg, Fe, and Cu in order of decreasing reactivity: Mg reacts vigorously with dilute HCl; Fe reacts slowly; Cu does not react.
Step-by-step solution
Step 1
Vigorous reaction with dilute acid → high reactivity → Mg is the most reactive.
Step 2
Slow reaction → intermediate reactivity → Fe is less reactive than Mg.
Step 3
No reaction with dilute acid → Cu is below H in reactivity series → least reactive of the three.
Answer
Decreasing reactivity: Mg > Fe > Cu.
Question
Explain why adding silver metal to copper sulfate solution does not produce a reaction.
Step-by-step solution
Step 1
In a displacement reaction, only a MORE reactive metal can displace a less reactive metal from its salt solution.
Step 2
Silver (Ag) is BELOW copper in the reactivity series: K > Na > ... > Cu > Ag > Au.
Step 3
Since Ag is less reactive than Cu, Ag cannot displace Cu²⁺ from the solution; no reaction occurs.
Answer
Silver is less reactive than copper (lower in the reactivity series); a less reactive metal cannot displace a more reactive one → no reaction.
Question
Describe the reactions of potassium, calcium, and iron with water or steam.
Step-by-step solution
Step 1
Potassium (very reactive): reacts vigorously with cold water → KOH + H₂; lilac flame observed.
2K+2H2O→2KOH+H2
Step 2
Calcium (reactive): reacts steadily with cold water → Ca(OH)₂ + H₂; bubbles form, white cloudy solution.
Ca+2H2O→Ca(OH)2+H2
Step 3
Iron (less reactive): does not react with cold water or steam under normal conditions; reacts very slowly with steam to form iron oxide + H₂.
3Fe+4H2O→Fe3O4+4H2
Answer
K: vigorous cold water reaction, lilac flame. Ca: steady cold water reaction, cloudy solution. Fe: no cold water reaction; slow reaction with steam.
Definitions to memorise and the exact keywords mark schemes credit for reactivity series answers — sharpened from recent examiner reports for the 2026 0654 sitting.
An ordered list of metals (and carbon and hydrogen) from most to least reactive, based on their tendency to lose electrons. Order: K > Na > Li > Ca > Mg > Al > C > Zn > Fe > H > Cu > Ag > Au.
A reaction in which a more reactive element displaces a less reactive element from its compound. e.g. Zn+CuSO4→ZnSO4+Cu
More reactive metals are more easily oxidised (lose electrons more readily). The reactivity series reflects the ease of losing electrons to form positive ions.
Hydrogen is included in the reactivity series between Al and Cu; metals above hydrogen react with dilute acids to produce H₂; metals below hydrogen (Cu, Ag, Au) do not.
The traps other students keep falling into on reactivity series questions — taken from recent Cambridge IGCSE 0654 examiner reports and mark schemes — and how to avoid them.
Why it happens
Students apply 'metal + metal salt → displacement' without checking the reactivity order.
How to avoid it
Always check the reactivity series: silver is BELOW copper → no displacement. Only metals ABOVE the target metal can displace it.
0654 Examiner Report 2022
Why it happens
Students apply the 'metal + acid → salt + H₂' rule to all metals.
How to avoid it
Copper is below hydrogen in the reactivity series; it does NOT react with dilute acids. Only metals above hydrogen in the series react with dilute HCl or H₂SO₄.
Why it happens
Students focus on the concept of displacement and forget to balance atoms/charges.
How to avoid it
Always balance the equation after writing it. For Zn + CuSO₄: 1 Zn replaces 1 Cu²⁺ (both 2+ ions) → balanced as written. For Na + CuSO₄: 2 Na needed for 1 Cu²⁺.
The things students keep getting wrong in this sub-topic, answered.