This chemistry grades 9-10 lesson on reactivity series notes gives the key ideas first, then worked examples and diagrams. After that, practise with the worksheet on reactivity series and check yourself with the quiz.
Quick answer: The reactivity series ranks metals by how easily they lose electrons. A more reactive metal displaces a less reactive one from its compound, which is a redox reaction. Also, we extract metals below carbon by heating their oxides with carbon, and metals above carbon need electrolysis.
Level: Chemistry grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: GCSE C4
Reactivity series notes: the key ideas
What is the reactivity series?
The reactivity series lists metals in order of how readily they form positive ions by losing electrons. Moreover, the more reactive the metal, the more vigorously it reacts with water, acid and oxygen.
Potassium and sodium sit at the top and react violently with cold water. In addition, magnesium burns brightly in air but reacts slowly with cold water. Also, zinc and iron react with dilute acid. Also, copper and gold do not react with dilute acid at all. Carbon and hydrogen are non-metals, but the series includes them because they help us decide how to extract metals.
| Metal | With cold water | With dilute acid | How it is extracted |
|---|---|---|---|
| Sodium | Vigorous, makes NaOH and H₂ | Violent | Electrolysis |
| Calcium | Steady bubbles of H₂ | Vigorous | Electrolysis |
| Magnesium | Very slow | Fast bubbles | Electrolysis |
| Zinc | None | Moderate | Heating with carbon |
| Iron | None | Slow | Heating with carbon |
| Copper | None | None | Heating with carbon or other methods |
What is a displacement reaction?
A more reactive metal will push a less reactive metal out of its compound. Moreover, the test is simple: add a metal to a solution of another metal’s salt and see whether a new metal appears. In addition, if it does, the added metal is more reactive.
A metal displaces another metal from its compound only if it is higher in the reactivity series. Fe + CuSO₄ → FeSO₄ + Cu, but Cu + FeSO₄ → no reaction.
Mei in Singapore drops a strip of zinc into copper(II) sulfate solution. Then, predict what happens and write the ionic equation.
Zinc is higher than copper, so it displaces copper. Also, the blue colour fades and a brown solid forms. Also, the sulfate ions are spectators: Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s).
What are oxidation and reduction?
Oxidation is gain of oxygen or loss of electrons. Moreover, reduction is loss of oxygen or gain of electrons. They always happen together, so the reaction is a redox reaction. A memory aid is OIL RIG: oxidation is loss, reduction is gain (of electrons).
Magnesium reacts with copper(II) oxide: Mg + CuO → MgO + Cu. Next, identify which substance oxidises and which one reduces.
Magnesium gains oxygen (it forms MgO), so it oxidises. Copper oxide loses oxygen, so it reduces. Mg is the reducing agent. In addition, in ionic terms, Mg → Mg²⁺ + 2e⁻ and Cu²⁺ + 2e⁻ → Cu.
How are metals extracted from their ores?
We find most metals as compounds in ores. A rock is an ore only if you can extract the metal from it profitably. Also, the method depends on the position of the metal relative to carbon.
- Below carbon (zinc, iron, copper): heat the oxide with carbon. Carbon is more reactive, so it takes the oxygen. Also, in the blast furnace, carbon monoxide does the work: Fe₂O₃ + 3CO → 2Fe + 3CO₂.
- Above carbon (aluminium and higher): carbon cannot reduce the oxide. Instead, we use electrolysis of the molten compound. Moreover, we dissolve aluminium oxide in molten cryolite to lower the temperature.
- Very unreactive metals (gold): found uncombined in the ground.
Reactivity series and the cost of extraction
Electrolysis needs huge amounts of electricity, so metals extracted this way are more expensive. We can treat low-grade copper ores by bioleaching, which uses bacteria, or by phytomining, which uses plants, so that we dig up less rock.
Reactivity series: a worked example on iron
A furnace in Odisha reduces 80 kg of iron(III) oxide: Fe₂O₃ + 3CO → 2Fe + 3CO₂ (Ar: Fe = 56, O = 16). Then, calculate the mass of iron.
M(Fe₂O₃) = 160 g/mol, so n = 80 000 ÷ 160 = 500 mol. The ratio Fe₂O₃ : Fe is 1 : 2, so n(Fe) = 1000 mol and m = 1000 × 56 = 56 000 g = 56 kg.
Carbon cannot extract a metal that is above carbon in the series. Many students write that carbon reduces aluminium oxide; it does not, because aluminium is more reactive than carbon.
Draw the series as a ladder and mark carbon on it. In addition, metals above the carbon rung need electricity; you can smelt metals below it with carbon.
- Series: K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au
- More reactive metals displace less reactive ones
- Oxidation is loss of electrons; reduction is gain (OIL RIG)
- Fe₂O₃ + 3CO → 2Fe + 3CO₂ in the blast furnace
- Metals above carbon are extracted by electrolysis
Metals by reactivity and how we extract them: frequently asked questions
How can I remember the order of the reactivity series?
Use a mnemonic for the main metals: potassium, sodium, calcium, magnesium, aluminium, (carbon), zinc, iron, (hydrogen), copper, silver, gold. Learn the positions of carbon and hydrogen.
Why does a more reactive metal displace a less reactive one?
The more reactive metal loses electrons more easily. Also, it gives its electrons to the ions of the less reactive metal, which become atoms and form a solid.
What is the difference between oxidation and reduction?
Oxidation is gain of oxygen or loss of electrons. Also, reduction is loss of oxygen or gain of electrons. Moreover, both always occur together in a redox reaction.
Why is aluminium extracted by electrolysis?
Aluminium is more reactive than carbon, so carbon cannot remove the oxygen from aluminium oxide. In addition, electricity passes through the molten oxide to separate the metal.
Why do some metals not need extraction?
Very unreactive metals such as gold do not form compounds easily, so we find them as the metal itself. Also, we can collect them by physical methods.
