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This lesson covers the reactivity series of metals as required by the AQA GCSE Combined Science Trilogy specification (8464). You must be able to recall the order of metals in the reactivity series, describe experiments to establish reactivity, and explain the link between a metal's position in the series and how it is extracted from its ore.
The reactivity series is a list of metals (and carbon and hydrogen as reference points) arranged in order of their reactivity, from the most reactive at the top to the least reactive at the bottom. A more reactive metal reacts more vigorously with water, acids and oxygen than a less reactive metal.
graph TB
K["Potassium — K"] --> Na["Sodium — Na"]
Na --> Li["Lithium — Li"]
Li --> Ca["Calcium — Ca"]
Ca --> Mg["Magnesium — Mg"]
Mg --> Al["Aluminium — Al"]
Al --> C["(Carbon — C)"]
C --> Zn["Zinc — Zn"]
Zn --> Fe["Iron — Fe"]
Fe --> H["(Hydrogen — H)"]
H --> Cu["Copper — Cu"]
Cu --> Ag["Silver — Ag"]
Ag --> Au["Gold — Au"]
Au --> Pt["Platinum — Pt"]
style K fill:#d32f2f,color:#fff
style Na fill:#e53935,color:#fff
style Li fill:#ef5350,color:#fff
style Ca fill:#ff7043,color:#fff
style Mg fill:#ff8a65,color:#fff
style Al fill:#ffb74d,color:#000
style C fill:#a1887f,color:#fff
style Zn fill:#fff176,color:#000
style Fe fill:#dce775,color:#000
style H fill:#81c784,color:#000
style Cu fill:#4db6ac,color:#fff
style Ag fill:#4dd0e1,color:#000
style Au fill:#4fc3f7,color:#000
style Pt fill:#64b5f6,color:#fff
Exam Tip: A common mnemonic for the reactivity series is "Please Stop Letting Cows Moo And Cry Zen, It Hurts Copper, Silver, Gold, Platinum" — but you should practise until you can recall the order without a mnemonic.
The most reactive metals react vigorously with cold water:
| Metal | Observation | Products |
|---|---|---|
| Potassium | Catches fire with a lilac flame, fizzes vigorously, moves across the surface | Potassium hydroxide + hydrogen |
| Sodium | Melts into a ball, fizzes, moves across the surface | Sodium hydroxide + hydrogen |
| Lithium | Fizzes gently, moves across the surface | Lithium hydroxide + hydrogen |
| Calcium | Sinks, steady fizzing, solution turns milky with Ca(OH)₂ | Calcium hydroxide + hydrogen |
$$\text{metal} + \text{water} \rightarrow \text{metal hydroxide} + \text{hydrogen}$$
For example:
$$2\text{Na}(s) + 2\text{H}_2\text{O}(l) \rightarrow 2\text{NaOH}(aq) + \text{H}_2(g)$$
Metals that do not react with cold water may react with steam:
$$\text{metal} + \text{steam} \rightarrow \text{metal oxide} + \text{hydrogen}$$
| Metal | Reactivity with Steam |
|---|---|
| Magnesium | Burns brightly, vigorous reaction |
| Zinc | Slow reaction when heated |
| Iron | Very slow reaction, reversible |
Example — magnesium and steam:
$$\text{Mg}(s) + \text{H}_2\text{O}(g) \rightarrow \text{MgO}(s) + \text{H}_2(g)$$
Metals above hydrogen in the reactivity series react with dilute acids to produce a salt and hydrogen gas:
$$\text{metal} + \text{acid} \rightarrow \text{salt} + \text{hydrogen}$$
| Metal + Acid | Products | Observation |
|---|---|---|
| Mg + 2HCl | MgCl₂ + H₂ | Vigorous fizzing, metal dissolves quickly |
| Zn + H₂SO₄ | ZnSO₄ + H₂ | Steady fizzing |
| Fe + 2HCl | FeCl₂ + H₂ | Slow fizzing, green solution forms |
| Cu + HCl | No reaction | Copper is below hydrogen |
Hold a burning splint near the mouth of the test tube. Hydrogen gives a characteristic squeaky pop.
A more reactive metal can displace a less reactive metal from a solution of its salt. This is a key way to determine the relative reactivity of metals.
$$\text{Zn}(s) + \text{CuSO}_4(aq) \rightarrow \text{ZnSO}_4(aq) + \text{Cu}(s)$$
Observations: The blue copper sulfate solution turns colourless (zinc sulfate), and a brown/orange coating of copper appears on the zinc.
| Reaction | Occurs? |
|---|---|
| Fe + CuSO₄ | Yes — iron is more reactive than copper |
| Cu + FeSO₄ | No — copper is less reactive than iron |
| Mg + ZnCl₂ | Yes — magnesium is more reactive than zinc |
| Ag + CuSO₄ | No — silver is less reactive than copper |
Exam Tip: If you are asked to predict whether a displacement reaction will occur, compare the positions of the two metals in the reactivity series. The metal in the compound must be less reactive than the free metal for displacement to happen.
| Mistake | Correction |
|---|---|
| Confusing the reactions of metals with cold water and steam | Metals that react with cold water form metal hydroxides; metals that react with steam form metal oxides |
| Forgetting that carbon and hydrogen are included as reference points, not metals | They are placed in the series to help decide on extraction methods |
| Thinking copper reacts with dilute acid | Copper is below hydrogen in the reactivity series and does not react with dilute acids |
| Mixing up the squeaky pop test | The squeaky pop tests for hydrogen, not any other gas |
Question: A student places a piece of magnesium ribbon into iron(II) sulfate solution. Predict and explain what happens.
Answer: