What Is Reactivity Series? A Visual Guide for Edexcel IGCSE Chemistry Students

The reactivity series: a hierarchy of metals

The reactivity series is an arrangement of metals in order of their reactivity, from the most reactive at the top to the least reactive at the bottom. It is a foundational concept in the Pearson Edexcel IGCSE Chemistry specification and one of the most commonly examined areas on both papers. Mastery of the reactivity series gives you the ability to predict whether a reaction will occur, explain why certain metals are extracted by electrolysis while others are extracted by carbon reduction, and understand the chemistry of corrosion. These edexcel igcse chemistry notes present the series with the precision the 4CH1 exam demands, together with worked examples and self-check questions.

Key facts: the reactivity order

The specification requires knowledge of the following metals in order of decreasing reactivity:

Metal	Symbol	Reactivity	Reaction with water	Reaction with dilute acid
Potassium	K	Very high	Vigorous, catches fire with lilac flame	Too dangerous to test
Sodium	Na	Very high	Vigorous, melts into a ball, fizzes rapidly	Too dangerous to test
Lithium	Li	High	Fizzes steadily on the surface	Too dangerous to test
Calcium	Ca	High	Fizzes, sinks, water turns milky with universal indicator turning purple	Vigorous fizzing
Magnesium	Mg	Moderate-high	Very slow reaction with cold water; reacts with steam	Vigorous fizzing, hydrogen produced
Aluminium	Al	Moderate	No visible reaction (oxide layer protects surface)	Reacts if oxide layer removed
Zinc	Zn	Moderate	No reaction with water	Steady fizzing
Iron	Fe	Low-moderate	No reaction with water; very slow with steam	Slow reaction, few bubbles
Copper	Cu	Low	No reaction	No reaction
Silver	Ag	Very low	No reaction	No reaction
Gold	Au	Very low	No reaction	No reaction

Memory aid: Many students use the mnemonic "Please Stop Letting Cows Munch Aluminium Zips In Copper Silver Gold" to recall the order. Any mnemonic will do, but the order itself must be committed to memory for the edexcel IGCSE exam.

Evidence for the reactivity series

The order is established experimentally by observing how metals react with water and with dilute hydrochloric or sulfuric acid. A more reactive metal reacts more vigorously, producing hydrogen gas faster. For example, magnesium reacts vigorously with dilute hydrochloric acid, producing rapid bubbling:

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Iron reacts much more slowly with the same acid under the same conditions. Copper does not react at all. These observations place magnesium above iron and iron above copper in the reactivity series.

Displacement reactions

Displacement reactions provide further evidence for the reactivity series and are a staple of the edexcel exam. A more reactive metal will displace a less reactive metal from a compound (either a metal oxide or an aqueous solution of a metal salt). A less reactive metal cannot displace a more reactive one.

Metals and metal oxides

When a reactive metal is heated with the oxide of a less reactive metal, the more reactive metal takes the oxygen:

Zn(s) + CuO(s) → ZnO(s) + Cu(s)

Zinc is above copper in the reactivity series, so zinc displaces copper from copper oxide. If you reversed this and heated copper with zinc oxide, nothing would happen because copper is less reactive than zinc.

Metals and aqueous metal salt solutions

When a piece of iron is placed into copper sulfate solution, the iron slowly dissolves and a reddish-brown coating of copper appears on the iron:

Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)

Iron is above copper in the series, so iron displaces copper from the solution. The blue colour of the solution fades (as Cu²⁺ ions are removed) and the solution becomes pale green (as Fe²⁺ ions enter).

Predicting displacement reactions

The rule is straightforward: compare the positions of the two metals in the reactivity series. If the uncombined metal is higher (more reactive), displacement occurs. If it is lower, no reaction takes place.

Metal added	Solution	Prediction
Magnesium	Zinc sulfate	Reaction occurs (Mg above Zn)
Copper	Iron(II) sulfate	No reaction (Cu below Fe)
Zinc	Lead(II) nitrate	Reaction occurs (Zn above Pb)
Silver	Copper sulfate	No reaction (Ag below Cu)

Oxidation, reduction and redox

Displacement reactions are examples of redox reactions. The specification requires two parallel definitions of oxidation and reduction:

Term	In terms of oxygen	In terms of electrons
Oxidation	Gain of oxygen	Loss of electrons
Reduction	Loss of oxygen	Gain of electrons

In the displacement reaction between iron and copper sulfate:

Iron is oxidised: Fe → Fe²⁺ + 2e^- (iron loses electrons)
Copper ions are reduced: Cu²⁺ + 2e^- → Cu (copper ions gain electrons)

Iron acts as the reducing agent (it causes reduction of Cu²⁺ by donating electrons). Copper sulfate acts as the oxidising agent (it causes oxidation of Fe by accepting electrons).

Exam precision: The edexcel igcse exam frequently asks you to identify what is oxidised and what is reduced in a given reaction. Always state both the substance and the reason: "Iron is oxidised because it loses electrons" earns both marks. Simply writing "iron is oxidised" without a reason may earn only one.

Rusting of iron

Iron rusts when it is exposed to both water and oxygen simultaneously. If either is absent, rusting does not occur. Rust is hydrated iron(III) oxide, and it is a flaky, porous substance that does not protect the underlying metal, so rusting continues until the iron is consumed.

Preventing rust

The specification identifies three methods:

Barrier methods: coating the iron with a material that prevents water and oxygen from reaching the surface. Examples include painting, oiling, greasing, plastic coating or tin plating.
Galvanising: coating the iron with a layer of zinc. Zinc is more reactive than iron and corrodes preferentially, protecting the iron even if the coating is scratched.
Sacrificial protection: attaching blocks of a more reactive metal (usually zinc or magnesium) to the iron structure. The more reactive metal corrodes instead of the iron. This method is used on ships' hulls and underground pipelines.

Galvanising and sacrificial protection both work because zinc (or magnesium) is higher in the reactivity series than iron. The more reactive metal is oxidised preferentially, donating its electrons to protect the iron from oxidation.

Worked example: predicting and explaining a displacement reaction

Question: A student places a strip of zinc into a solution of copper(II) sulfate. Predict whether a reaction occurs and write a balanced equation. Identify the substance that is oxidised and the substance that is reduced.

Step 1: Predict. Zinc is above copper in the reactivity series. Therefore, zinc will displace copper from the solution. A reaction occurs.

Step 2: Write the equation.
Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s)

Step 3: Identify redox.
Zinc is oxidised because it loses electrons: Zn → Zn²⁺ + 2e^-
Copper ions are reduced because they gain electrons: Cu²⁺ + 2e^- → Cu

Observations: The zinc strip dissolves gradually. A reddish-brown deposit of copper forms on the zinc. The blue colour of the solution fades as Cu²⁺ ions are removed and is replaced by a colourless solution of ZnSO₄.

Extraction of metals and the reactivity series

The method used to extract a metal from its ore is directly related to its position in the reactivity series. Metals below carbon can be extracted by heating their oxides with carbon (reduction by carbon). Metals above carbon are too reactive for carbon reduction and must be extracted by electrolysis, which requires more energy and is therefore more expensive.

Iron is below carbon. It is extracted in a blast furnace by reducing iron oxide with carbon (as coke): Fe₂O₃ + 3CO → 2Fe + 3CO₂
Aluminium is above carbon. It is extracted from purified aluminium oxide (alumina) by electrolysis of the molten ore dissolved in cryolite.

Unreactive metals such as gold and silver occur naturally as the uncombined element because they are too unreactive to form stable compounds with other elements in the Earth's crust.

Self-check questions

Place these metals in order of decreasing reactivity: copper, magnesium, zinc, iron, sodium.
Predict whether a reaction occurs when a strip of copper is placed in zinc sulfate solution. Explain your answer.
Write a balanced symbol equation for the reaction between magnesium and dilute hydrochloric acid. Include state symbols.
In the reaction between zinc and copper oxide, identify which substance is oxidised and which is reduced. Give your reasons in terms of electron transfer.
Explain why iron rusts only when both water and oxygen are present.
Describe how galvanising protects iron from rusting, even if the zinc coating is scratched.

The reactivity series explained at this level spans prediction, observation and explanation. When students ask what is reactivity series igcse, the answer encompasses metal ordering, displacement reactions, redox terminology and the practical application of these principles to metal extraction and corrosion prevention. Every part connects logically: the order determines which reactions happen, which metals displace which, how extraction is done, and why sacrificial protection works.

Edexcel igcse reactivity series questions test both recall and application, so the edexcel igcse chemistry definition of oxidation, reduction, displacement and corrosion prevention must be stated with precision. These edexcel igcse chemistry explained notes match the standard expected by the Pearson Edexcel IGCSE Chemistry mark scheme. For further edexcel igcse chemistry notes and practice questions, the Green Bridge CBT platform provides topic-filtered assessments with detailed model answers.