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The order of reactivity of metals, displacement reactions, oxidation and reduction, and how metals are extracted from their ores.
Specification references this topic covers: AQA 5.4.1, 5.4.2; Edexcel C0.2, C0.4, C3.28, C4.1, C4.2, C4.3, C4.4, C4.5.
Some metals, like gold, stay shiny for thousands of years. Others, like sodium, burst into action when they touch water. This difference is called reactivity.
It matters because reactivity decides how we get metals out of rocks. It also tells us which metals are safe to use for pipes, jewellery and tools.
By the end you will be able to put metals in order of reactivity. You will explain displacement, oxidation and reduction. You will also say how a metal is extracted from its ore.
The reactivity series lists metals from most to least reactive. The order is potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, copper, silver, gold. Carbon and hydrogen are also placed in the list for comparison. Carbon sits between aluminium and zinc. Hydrogen sits between iron and copper.
Think of a league table. The top four react with cold water. They make a hydroxide and hydrogen: Ca + 2H₂O → Ca(OH)₂ + H₂.
Metals above hydrogen react with dilute acid. They make a salt and hydrogen: Mg + 2HCl → MgCl₂ + H₂. A faster stream of bubbles means a more reactive metal. Copper does not react.
A more reactive metal can push a less reactive metal out of its compound. This is called displacement. Think of a better player replacing a weaker one on the pitch.
Zinc is more reactive than copper, so zinc displaces copper from copper sulfate: Zn + CuSO₄ → ZnSO₄ + Cu. Pink-brown copper appears, and the blue colour fades.
If the metal added is less reactive, nothing happens. Copper does not displace zinc from zinc sulfate. You can use these results to put metals in order of reactivity.
Oxidation is the gain of oxygen. Reduction is the loss of oxygen. Both happen together in the same reaction.
In 2Mg + O₂ → 2MgO, magnesium gains oxygen, so it is oxidised. In CuO + H₂ → Cu + H₂O, copper oxide loses oxygen, so it is reduced. Hydrogen gains oxygen, so it is oxidised.
Higher tier: oxidation is also the loss of electrons and reduction is the gain of electrons. Remember OIL RIG: Oxidation Is Loss, Reduction Is Gain. Metals are oxidised when they form positive ions.
Higher tier. Look at Zn + CuSO₄ → ZnSO₄ + Cu. The sulfate ions are the same on both sides. They are spectator ions, so we leave them out.
The ionic equation is Zn + Cu²⁺ → Zn²⁺ + Cu. Zinc atoms lose two electrons, so they are oxidised. Copper ions gain two electrons, so they are reduced.
Half equations show each change on its own. Zn → Zn²⁺ + 2e⁻ is oxidation. Cu²⁺ + 2e⁻ → Cu is reduction. The electrons lost must equal the electrons gained.
An ore is a rock that contains a metal compound. Gold is so unreactive that it is found as the metal itself. Most other metals must be extracted from their ores.
Metals less reactive than carbon, such as iron and zinc, are extracted by heating their oxides with carbon. Carbon removes the oxygen: 2Fe₂O₃ + 3C → 4Fe + 3CO₂.
Metals more reactive than carbon, such as aluminium, cannot be extracted this way. They need electrolysis of the molten compound. This uses a lot of electricity, so it is expensive.
In the blast furnace, iron(III) oxide is reduced by carbon monoxide: Fe₂O₃ + 3CO → 2Fe + 3CO₂. The iron oxide loses oxygen, so it is reduced. The carbon monoxide gains oxygen, so it is oxidised.
The thermite reaction is a displacement from an oxide. Aluminium displaces iron: 2Al + Fe₂O₃ → Al₂O₃ + 2Fe. The heat is so great that the iron is molten.
Carbon is cheap, so it is used whenever it can do the job. Electrolysis is only used for metals that carbon cannot reduce.
The reactivity series puts metals in order. More reactive metals react faster with water and acid.
A more reactive metal displaces a less reactive one from its compound.
Oxidation is gain of oxygen or loss of electrons. Reduction is loss of oxygen or gain of electrons.
Metals less reactive than carbon are extracted with carbon. More reactive metals need electrolysis.
Name the products when magnesium reacts with dilute hydrochloric acid.
Answer: magnesium chloride and hydrogen
A piece of zinc is added to copper sulfate solution. Describe what you see and explain why this happens.
Answer: Zinc displaces copper because it is more reactive. Pink-brown copper forms and the blue colour fades.
Explain, using electrons, why Zn + Cu²⁺ → Zn²⁺ + Cu is a redox reaction.
Answer: Zinc loses electrons so it is oxidised, and copper ions gain electrons so they are reduced.
Reactivity series and extracting metals practice questions for GCSE Combined Science Chemistry. Try each one, then open the answer. Easy questions come first.
Name the gas made when a metal reacts with a dilute acid.
Answer: hydrogen
Which is more reactive, zinc or copper?
Answer: zinc
Name the type of reaction where a more reactive metal takes the place of a less reactive metal in a compound.
Answer: displacement
What is the term for the loss of oxygen from a compound?
Answer: reduction
Name the salt made when zinc reacts with dilute hydrochloric acid.
Answer: zinc chloride
What is the term for the gain of oxygen by a substance?
Answer: oxidation
Which metal could be extracted from its oxide by heating with carbon: iron or aluminium?
Answer: iron
Balance the equation: __ Ca + __ H₂O → __ Ca(OH)₂ + __ H₂. Give the numbers in order, separated by commas.
Answer: 1, 2, 1, 1
Longer questions in the style of a written paper, with the marking points. These are Yumio practice questions.
A student adds pieces of four metals to dilute hydrochloric acid and observes the bubbling. (a) Magnesium fizzes quickly and iron fizzes slowly. Which metal is more reactive? [1 mark] (b) Write a word equation for the reaction of magnesium with hydrochloric acid. [2 marks] (c) Copper does not react. Explain why. [1 mark]
Answer: (a) magnesium (b) magnesium + hydrochloric acid → magnesium chloride + hydrogen (c) Copper is less reactive than hydrogen.
Zinc reacts with copper(II) sulfate solution: Zn + CuSO₄ → ZnSO₄ + Cu. (a) Write the ionic equation. [1 mark] (b) Identify the species that is oxidised and explain your answer in terms of electrons. [2 marks] (c) Name the spectator ion. [1 mark] (d) State one observation. [1 mark]
Answer: (a) Zn + Cu²⁺ → Zn²⁺ + Cu (b) Zinc is oxidised because it loses two electrons. (c) sulfate (d) The blue solution fades or a pink-brown solid forms.
Putting carbon below aluminium in the series for extraction
Carbon is more reactive than zinc and less reactive than aluminium. Aluminium needs electrolysis.
Saying a metal is reduced when it forms a positive ion
It is oxidised because it loses electrons.
Writing the products of an acid with a metal as a metal oxide and water
A metal and an acid make a salt and hydrogen.
Saying a displacement happens when the metal added is less reactive
Only a more reactive metal displaces a less reactive one.
Reactivity series and extracting metals is on both Foundation and Higher papers for GCSE Combined Science Chemistry, aimed at around grade 5.
Putting carbon below aluminium in the series for extraction. Carbon is more reactive than zinc and less reactive than aluminium. Aluminium needs electrolysis.
Open Show answer under each question on this page. The questions are Yumio practice questions, not past exam questions.
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