The reactivity series — AQA GCSE Combined Science
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The reactivity series explained
Metal atoms lose electrons to form positive ions, for example Na → Na⁺ + e⁻ and Mg → Mg²⁺ + 2e⁻.
Read the full explanation
The more readily a metal forms positive ions, the more reactive it is. Reactivity is therefore linked to the tendency to form positive ions, not to density, hardness or melting point. The reactivity series places metals in order, with potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper from most to least reactive among those listed. The order is established by observing reactions with water and dilute acids: potassium reacts violently with cold water, sodium and lithium react vigorously, calcium reacts steadily, magnesium reacts very slowly with cold water but rapidly with dilute acid, zinc and iron react more slowly with acid, and copper does not react with water or dilute acid.
The non-metals hydrogen and carbon are often included in the reactivity series.
The reactivity series is usually a list of metals in order of how vigorously they react, but hydrogen and carbon are non-metals that are often placed within it as reference points. Hydrogen is shown as a non-metal against which metals can be compared: metals above hydrogen displace it from dilute acids, while metals below it generally do not. Carbon is shown as a non-metal that can reduce metal oxides when it is more reactive than the metal, which is how carbon is used in extracting some metals from their ores. For example, carbon reduces zinc oxide because carbon is above zinc, but carbon cannot reduce aluminium oxide because aluminium is above carbon. Including these non-metals lets chemists predict displacement and reduction behaviour, even though they are not metals.
A more reactive metal can displace a less reactive metal from a compound.
Displacement occurs when a more reactive metal takes the place of a less reactive metal in a compound. The more reactive metal forms a compound, and the less reactive metal is released as the element. For example, if magnesium is added to copper sulfate solution, magnesium is above copper in the reactivity series, so magnesium displaces copper: magnesium sulfate forms and copper metal appears as a brown solid. The reaction can be written as Mg + CuSO₄ → MgSO₄ + Cu. The same principle applies to solid metal oxides heated with a more reactive metal, and it explains why displacement is used to predict whether a reaction happens. If the added metal is less reactive than the metal in the compound, no displacement occurs.
recall and describe the reactions, if any, of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with water or dilute acids and where appropriate, to place these metals in order of reactivity
You need to recall and describe how each named metal behaves with water or dilute acid, then use that evidence to rank them. Potassium, sodium and lithium react vigorously with cold water, giving hydrogen and an alkaline hydroxide; calcium reacts steadily; magnesium reacts very slowly with cold water but rapidly with steam. Zinc and iron react with dilute acid to form a salt and hydrogen but not with cold water, while copper reacts with neither. Reactivity reflects how easily a metal atom loses electrons to form a positive ion. A common method adds a small cleaned sample to water or acid and records fizzing, movement, temperature change and any flame, then compares results to build the order potassium > sodium > lithium > calcium > magnesium > zinc > iron > copper.
explain how the reactivity of metals with water or dilute acids is related to the tendency of the metal to form its positive ion
A metal's reactivity with water or dilute acid depends on how readily its atoms lose electrons to form positive ions. Metals high in the reactivity series, such as potassium, sodium, calcium and magnesium, have atoms that lose outer-shell electrons easily, so they form positive ions readily and react vigorously. For example, sodium reacts rapidly with cold water, producing sodium ions, Na⁺, and hydrogen gas. Metals low in the series, such as copper, silver and gold, hold their electrons more strongly, form positive ions only with difficulty, and therefore react slowly or not at all. When a metal reacts, it is oxidised: M → Mⁿ⁺ + n e⁻. The greater the tendency to form positive ions, the more reactive the metal and the more vigorous its reaction with water or dilute acid.
deduce an order of reactivity of metals based on experimental results.
To deduce an order of reactivity from experimental results, compare how vigorously different metals react with water or dilute acid, or compare displacement reactions. For example, if metal A displaces metal B from a solution of a B salt, then A is more reactive than B. If metal C reacts more vigorously with dilute hydrochloric acid than metal D, producing bubbles faster and a greater temperature rise, then C is more reactive than D. By ranking several metals from most to least vigorous, you build a reactivity order. The order must be consistent with all the evidence: a metal that displaces another is placed above it, and a metal that reacts more vigorously is placed above a less vigorous one. This deduced order can then be compared with the standard reactivity series.
Your focus
- Describe how metal atoms form positive ions and relate this to reactivity.
- Place the listed metals in order of reactivity using reactions with water and dilute acids.
- Justify the position of a metal in the reactivity series using observed evidence.
Show all 18 objectives
- Identify hydrogen and carbon as non-metals that are often included in the reactivity series.
- Use the position of a metal relative to hydrogen to predict whether it displaces hydrogen from dilute acid.
- Use the position of carbon relative to a metal to predict whether carbon can reduce that metal oxide.
- State that a more reactive metal displaces a less reactive metal from its compound.
- Use the reactivity series to predict whether a displacement reaction will occur.
- Describe observations and write equations for a named displacement reaction.
- Recall the reactions of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with water or dilute acids.
- Describe the observations that show whether each reaction occurs and how vigorous it is.
- Place the named metals in order of reactivity and justify the order using the reactions.
- Describe how the reactivity of a metal is related to its tendency to form a positive ion.
- Use the reactivity series to predict whether a metal reacts with water or dilute acid and how vigorously.
- Write a word or symbol equation for the reaction of a metal with water or dilute acid and identify the positive ion formed.
- Interpret experimental results to compare the reactivity of different metals.
- Construct a reactivity order from displacement reactions and reactions with water or dilute acid.
- Justify the position of a metal in a deduced reactivity order using the evidence provided.
The reactivity series exam tips
Marking Points
- Metal atoms form positive ions by losing electrons, for example Na → Na⁺ + e⁻ and Ca → Ca²⁺ + 2e⁻.
- The reactivity of a metal is related to its tendency to form positive ions; a greater tendency means greater reactivity.
- The reactivity series orders metals from most reactive to least reactive, and the listed order is potassium, sodium, lithium, calcium, magnesium, zinc, iron, copper.
- Reactions with cold water and dilute acids provide the evidence used to place metals in the series.
- Potassium, sodium and lithium react vigorously with cold water, while copper shows no reaction with water or dilute acid.
- Magnesium reacts very slowly with cold water but reacts readily with dilute acid, so the two tests can give different apparent rates.
- Observations such as fizzing, metal dissolving, temperature rise and gas produced are used to compare reactivity.
- Hydrogen and carbon are non-metals, not metals, yet they are often placed within the reactivity series as reference points.
- Hydrogen is used to judge whether a metal reacts with dilute acid: metals above hydrogen displace hydrogen from the acid, while metals below hydrogen generally do not.
- Carbon is used to judge whether a metal oxide can be reduced by carbon: carbon reduces the oxide if carbon is above the metal in the series.
- The position of a non-metal in the series is a comparison of reactivity, not a claim that it is a metal.
- A concrete example is that carbon reduces zinc oxide to zinc because carbon is above zinc, but carbon does not reduce aluminium oxide because aluminium is above carbon.
- Hydrogen and carbon are included so that displacement and reduction can be predicted using one ordered list.
- A more reactive metal displaces a less reactive metal from its compound, so the more reactive metal takes the place of the less reactive metal.
- The more reactive metal becomes part of a new compound, while the less reactive metal is released as the element.
- The relative positions in the reactivity series decide whether displacement happens: the added metal must be above the metal in the compound.
- A word equation or symbol equation can represent the change, for example magnesium + copper sulfate → magnesium sulfate + copper, or Mg + CuSO₄ → MgSO₄ + Cu.
- Observable evidence can include colour change, disappearance of the more reactive metal and appearance of the less reactive metal.
- If the added metal is below the metal in the compound, no displacement occurs.
- Recalls that potassium, sodium and lithium react vigorously with cold water, producing hydrogen and an alkaline metal hydroxide.
- Describes calcium reacting steadily with water and magnesium reacting very slowly with cold water but vigorously with steam.
- Explains that zinc and iron react with dilute acid to form a salt and hydrogen, but do not react appreciably with cold water.
- States that copper does not react with cold water or dilute acid and is placed below hydrogen.
- Uses the reactions to place the metals in order: potassium > sodium > lithium > calcium > magnesium > zinc > iron > copper.
- Links the order to the ease of forming a positive ion by losing electrons.
- Reactivity is linked to the ease with which a metal atom loses one or more electrons to form a positive ion.
- A metal that forms positive ions readily, such as sodium forming Na⁺, is described as reactive and reacts vigorously with water or dilute acid.
- A metal that forms positive ions only with difficulty, such as copper forming Cu²⁺, is unreactive and reacts slowly or not at all with water or dilute acid.
- The reaction with water or dilute acid involves the metal being oxidised, for example M → Mⁿ⁺ + n e⁻, and the observation of bubbles, heat or a metal salt solution supports the link to ion formation.
- The order of reactivity observed experimentally, for example potassium more reactive than sodium more reactive than calcium more reactive than magnesium more reactive than zinc more reactive than iron more reactive than copper, matches the tendency to form positive ions.
- Identify the experimental evidence available, such as rate of bubbling, temperature change, or whether a displacement reaction occurs.
- Compare the metals in pairs: the metal that reacts more vigorously or displaces the other is the more reactive.
- Rank the metals from most reactive to least reactive using all the comparisons, ensuring the final order is consistent with every observation.
- Use displacement results to place a metal above another in the reactivity series, for example if zinc displaces copper from copper sulfate solution then zinc is more reactive than copper.
- Explain that the deduced order matches the tendency of each metal to form a positive ion, with more reactive metals forming ions more readily.
Examiner Tips
- 💡Learn the listed order as a sequence and practise writing it from most to least reactive without prompts.
- 💡When comparing two metals, quote a specific observation such as rate of fizzing or temperature change rather than saying one is 'more reactive' with no evidence.
- 💡Link each reactivity statement back to positive ion formation, for example 'potassium is more reactive because it forms K⁺ more readily than iron forms Fe²⁺'.
- 💡Check that any ion you write has the correct charge, such as 1⁺ for Na⁺ and 2⁺ for Mg²⁺.
- 💡State clearly that hydrogen and carbon are non-metals when you refer to their position in the series.
- 💡Use the phrases above hydrogen and below hydrogen to explain acid reactions, and above the metal to explain reduction by carbon.
- 💡Give one named example, such as carbon reducing zinc oxide, to show the predictive use of the series.
- 💡Check the reactivity series before predicting displacement, and state which metal is more reactive.
- 💡Balance symbol equations for displacement so the number of each type of atom is the same on both sides.
- 💡Link observations to the reaction, such as a colour change or a solid forming, rather than only naming the products.
- 💡Practise writing the reactivity order from memory, then check it against the reactions you can describe.
- 💡In extended answers, compare at least three metals and use comparative language such as 'more reactive than'.
- 💡Include the state or appearance of the metal and the key observation, such as fizzing or a flame, to show you are describing evidence.
- 💡When explaining reactivity, always name the metal ion formed and state that the metal atom loses electrons, for example magnesium forms Mg²⁺ by losing two electrons.
- 💡Link your explanation to a specific observation, such as the rate of bubbling or temperature rise, to show how the tendency to form positive ions is demonstrated experimentally.
- 💡Use the reactivity series to justify your answer: place the metal in the series and state whether it is above or below hydrogen, then explain what that means for its reaction with water or dilute acid.
- 💡Present your deduced order as a clear list from most reactive to least reactive, and briefly state the evidence for each adjacent pair.
- 💡If the question gives a table of results, look for the metal with the fastest reaction or the greatest temperature rise and place it at the top of your order.
- 💡When using displacement reactions, remember that the more reactive metal displaces the less reactive metal from its compound, so the displacing metal goes above the displaced metal.
Common Mistakes
- Writing ion symbols without charge, such as Na or Mg, instead of Na⁺ and Mg²⁺; the positive charge is the key feature of the ion formed.
- Placing copper above iron in the series because copper is familiar or used in wires; copper is less reactive than iron and does not react with dilute acid.
- Assuming that a more reactive metal must be denser or harder; reactivity depends on the tendency to form positive ions, not on physical properties.
- Saying that magnesium 'does not react with water' without qualification; it reacts very slowly with cold water, so state the condition and the acid result separately.
- Calling hydrogen and carbon metals because they appear in the reactivity series; the correction is that they are non-metals included as reference points.
- Thinking any metal below hydrogen will fizz in dilute acid; the correction is that metals below hydrogen generally do not displace hydrogen from dilute acid.
- Assuming carbon can reduce every metal oxide; the correction is that carbon only reduces oxides of metals below carbon in the series, such as zinc oxide, not aluminium oxide.
- Writing the displacement the wrong way round, for example saying copper displaces magnesium from magnesium sulfate; the correction is that the more reactive metal, magnesium, displaces the less reactive copper.
- Forgetting that the displaced metal appears as the element, not as a compound; the correction is to show copper as Cu, not as copper sulfate.
- Assuming any metal displaces any other metal; the correction is to check the reactivity series and only predict displacement when the added metal is more reactive.
- Claiming magnesium reacts vigorously with cold water. Correction: magnesium reacts very slowly with cold water and rapidly with steam.
- Writing that copper reacts with dilute acid to give hydrogen. Correction: copper is below hydrogen, so it does not displace hydrogen from dilute acids.
- Forgetting the salt in the products of a metal–acid reaction. Correction: name both the salt and hydrogen, for example zinc + sulfuric acid → zinc sulfate + hydrogen.
- Error: saying that reactivity depends on the metal's density or melting point. Correction: reactivity depends on the tendency of the metal atom to lose electrons and form a positive ion, not on physical properties such as density.
- Error: writing that a reactive metal gains electrons to form a positive ion. Correction: a positive ion forms when a metal atom loses electrons, for example Na → Na⁺ + e⁻.
- Error: stating that copper reacts vigorously with cold water because it is a metal. Correction: copper is low in the reactivity series, forms positive ions only with difficulty, and does not react with cold water or dilute acid under normal laboratory conditions.
- Error: assuming that the metal that produces the most gas is always the most reactive without considering the time taken or the amount of metal used. Correction: compare the rate of reaction under the same conditions, or use displacement evidence, to make a fair comparison.
- Error: placing a metal above another just because it is higher in a remembered list, without using the experimental results. Correction: the deduced order must be based on the results provided, not on memory alone.
- Error: ignoring a displacement result that contradicts the rest of the order. Correction: check all pairs of metals and adjust the order so that every observation is consistent.