The Reactivity Series

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.

What Is the Reactivity Series?

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.

Reactions of Metals With Water

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

General Equation

$$\text{metal} + \text{water} \rightarrow \text{metal hydroxide} + \text{hydrogen}$$

For example:

$$2\text{Na}(s) + 2\text{H}_2\text{O}(l) \rightarrow 2\text{NaOH}(aq) + \text{H}_2(g)$$

Reactions of Metals With Steam

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:

$$\text{Mg}(s) + \text{H}_2\text{O}(g) \rightarrow \text{MgO}(s) + \text{H}_2(g)$$

Reactions of Metals With Dilute Acids

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

Testing for Hydrogen Gas

Hold a burning splint near the mouth of the test tube. Hydrogen gives a characteristic squeaky pop.

Displacement Reactions

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.

Rules for Displacement

A more reactive metal displaces a less reactive metal from its compound.
A less reactive metal cannot displace a more reactive metal — no reaction occurs.

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.

Common Mistakes

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

Worked Example

Question: A student places a piece of magnesium ribbon into iron(II) sulfate solution. Predict and explain what happens.

Answer:

Magnesium is higher in the reactivity series than iron.
Therefore, magnesium displaces iron from iron(II) sulfate.
Equation: Mg(s) + FeSO₄(aq) → MgSO₄(aq) + Fe(s)
Observations: The magnesium ribbon dissolves, the green colour of the solution fades (the iron(II) ions are replaced by colourless magnesium ions), and dark grey iron metal appears.

Summary

The reactivity series ranks metals from most reactive (potassium) to least reactive (platinum), with carbon and hydrogen as reference points.
The most reactive metals react vigorously with cold water, forming metal hydroxides and hydrogen.
Less reactive metals react with steam, forming metal oxides and hydrogen.
Metals above hydrogen react with dilute acids to produce a salt and hydrogen.
A more reactive metal displaces a less reactive metal from its compound in solution.
The reactivity series determines the method of extraction: metals above carbon require electrolysis; metals below carbon are extracted by reduction with carbon.