3.5.1Movement and Interactions
A Reactivity Series For Metals
15 min read 8 parts Lesson 54 of 59 1 quiz
Section 1 of 8A Reactivity Series For Metals
1
The reactivity series is deduced from how vigorously metals react with cold water, steam and dilute acids; carbon and hydrogen are included to show which metals they can displace.
2
Metals above hydrogen displace hydrogen from dilute acids; those below (Cu, Ag, Au) do not.
3
A metal will displace a less reactive metal from a solution of its salt or from its oxide; no reaction occurs if the added metal is less reactive.
4Observations in displacement
Observations in displacement the more reactive metal gets coated with the less reactive metal, the solution colour may change (e.g. blue copper(II) sulfate fades), and the mixture warms up (exothermic).
5
(Supplement) Reactivity depends on how easily atoms lose electrons to form positive ions. In displacement, the more reactive metal atoms are oxidised and the less reactive metal ions are reduced — a redox reaction.
6
(Supplement) Aluminium seems unreactive (e.g. no reaction with water, slow with acid) because a thin, protective layer of aluminium oxide covers its surface.
7
Rusting of iron and steel needs both oxygen (from air) and water; the product is hydrated iron(III) oxide, a flaky orange-brown solid that falls off and exposes more iron.
8
Barrier methods (paint, grease, plastic) work by preventing oxygen and water reaching the iron; if the barrier is scratched, rusting starts.
9
Galvanising coats iron with zinc; it acts as a barrier and, even when scratched, zinc protects the iron sacrificially.
10
(Supplement) In sacrificial protection a more reactive metal (Zn or Mg) is attached to iron; it loses electrons more readily than iron, so it corrodes instead and the iron is not oxidised. The block must be replaced from time to time.
11Core
Reactivity can also be compared by temperature change: react equal amounts of each metal (same size and form) with the same volume and concentration of acid or salt solution. The bigger the temperature rise, the more reactive the metal.
12Supplement
Only a metal above iron in the reactivity series (e.g. zinc, magnesium) gives sacrificial protection. A less reactive metal such as copper or tin cannot: once its coating is scratched, the iron loses electrons more readily and rusts even faster.
Section 2 of 8Process & sequence
- Set up three test tubes each containing an iron nail.
- Tube Anail in tap water open to air (water + oxygen).
- Tube B
- nail in boiled water covered with a layer of oil (boiling removes dissolved air;
- oil stops air re-dissolving) — no oxygen.
- nail in boiled water covered with a layer of oil (boiling removes dissolved air;
- Tube Cnail in dry air with anhydrous calcium chloride as a drying agent and a stopper — no water.
- Leave for several days and observe which nail develops orange-brown rust.
- Concludeonly tube A rusts, so both oxygen and water are needed for rusting.
How sacrificial protection workswrite these steps in this order; each step is a marking point.
- Zinc (more reactive) is in contact with iron
- Oxygen and water reach the metals
- Zinc loses electrons more readily than iron
- Zinc is oxidised to Zn2+ and corrodes
- Iron is not oxidised, so it does not rust
Section 3 of 8Compare
| Metal | Cold water | Steam | Dilute acid |
|---|---|---|---|
| Potassium, sodium, calcium | react (hydroxide + H2) | dangerous / not done | violent (Ca vigorous) |
| Magnesium | very slow | reacts (MgO + H2) | fast fizzing |
| Aluminium | no (oxide layer) | slow | slow at first, then steady |
| Zinc, iron | no | react when heated (oxide + H2) | moderate / slow |
| Copper, silver, gold | no | no | no |
| Method | How it works | Example use |
|---|---|---|
| Painting | barrier keeps out O2 and H2O | cars, bridges |
| Greasing / oiling | barrier; good for moving parts | bicycle chains, tools |
| Plastic coating | barrier | garden furniture, wire fences |
| Galvanising (zinc) | barrier + sacrificial protection | dustbins, roofing, nails |
| Sacrificial blocks (Mg/Zn) | more reactive metal is oxidised instead of iron | ship hulls, pipelines |
Section 4 of 8Worked examples
Worked examples
1.28 g
Zinc is added to excess copper(II) sulfate solution. 1.30 g of zinc reacts. Calculate the mass of copper formed (Ar Zn = 65, Cu = 64).
- Zn + CuSO4 → ZnSO4 + Cu.
- Moles Zn = 1.30 ÷ 65 = 0.0200 mol.
- Ratio 1 : 1, so 0.0200 mol Cu.
- Mass Cu = 0.0200 × 64 = 1.28 g.
R > P > Q
Metals P, Q, R: P displaces Q from Q sulfate; R displaces P from P sulfate; Q does not displace R. Place them in order of reactivity and explain.
- R displaces P, so R > P.
- P displaces Q, so P > Q.
- Order (most to least reactive): R > P > Q.
- Q not displacing R agrees, as Q is less reactive than R.
Deduce the order of reactivity from these displacement results.
- Mg + FeSO4 → MgSO4 + Fe; Zn + FeCl2 → ZnCl2 + Fe; Fe + 2AgNO3 → Fe(NO3)2 + 2Ag.
- Cu + FeCl2 — no reaction; Ag + CuSO4 — no reaction; Zn + MgCl2 — no reaction.
- A reaction means the added metal is more reactive than the one in the salt, so Mg > Zn (no Zn/MgCl2 reaction), Zn > Fe, Fe > Cu > Ag.
- Order, most reactive first: Mg > Zn > Fe > Cu > Ag.
Section 5 of 8Keep going
Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620: what to do next
These Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 notes covered the key ideas, worked examples and exam technique for this topic. Check your Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 understanding with the practice questions below, then reread any Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 point you were unsure about before moving on.
Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620: revision checklist
- Revise the main Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 definitions until you can write them from memory.
- Practise Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 exam questions under timed conditions.
- Link each Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 idea to a diagram or a worked example.
- List the common Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 mistakes and how to avoid them.
- Explain one Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 idea out loud as if teaching a friend.
- Summarise Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 in five key points on a revision card.
- Check which command words appear most often in Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 questions.
- Practice: Reactivity Series & Corrosion of Metals IGCSE Chemistry 0620 practice questions
- Previous lesson: 8.3 Properties, Uses & Alloys of Metals — 0620 Notes
- Next lesson: 8.5 Extraction of Metals — 0620 Notes
- Course: Cambridge IGCSE Chemistry 0620 — all units
- Official syllabus: Cambridge IGCSE Chemistry 0620 syllabus
Section 6 of 8Key terms
Section 7 of 8Command terms
Command terms
State / Name
Give a short answer only; no explanation is needed (1 mark = 1 fact).
Define
Give the precise meaning. Learn the syllabus definitions word-for-word: every keyword in the definition is a marking point.
Describe
Say what happens / what the data show, with key features and figures. Do not give reasons.
Explain
Give reasonswhat happens AND why/how, linked with “because”, “so”, “therefore”.
Suggest
Apply knowledge to an unfamiliar situation; any sensible, scientifically-based answer can score.
Compare
Give similarities AND differences, each as a direct comparison (“X is … whereas Y is …”).
Outline
Set out the main points briefly.
Calculate
Work out from given facts; show working, give the unit and the requested significant figures.
Identify
Name/select from given information.
Predict
Give an expected result without a full justification.
Evaluate
Judge the importance or quality of the evidence/method, with reasons.
Section 8 of 8Exam technique
Keywords the mark scheme looks for in this lesson
Keywords the mark scheme looks for in this lesson
Reactivity series · Displacement reaction (metals) · Tendency to form positive ions · Oxidation · Reduction · Corrosion · Rusting · Barrier method · Galvanising · Sacrificial protection · Oxide layer on aluminium · Ionic equation
Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.
How to get full marks (examiner guidance)
1
Use the exact scientific term and learn syllabus definitions word-for-word.
2
Write “rate of … increases”, not “… increases”.
3
Say “concentration gradient”, never just “gradient”; name particles precisely (atoms, molecules, ions) — never “it”.
4
Give units with every numerical answer and use the significant figures asked for; show all working.
5
Compare = a similarity AND a difference; describe = what happens; explain = why it happens.
6
Repeats let you identify anomalies and calculate a mean — they do not make an experiment “valid”.
Words to avoid
1
rusting needs airrusting needs both oxygen and water
2
zinc protects iron because it is strongerzinc is more reactive than iron, so it loses electrons (is oxidised) instead of iron
3
rust is iron oxiderust is hydrated iron(III) oxide
4
aluminium is unreactivealuminium appears unreactive because of a protective oxide layer
5
copper displaces zinczinc displaces copper from copper(II) sulfate because zinc is more reactive
6
paint stops iron reactingpaint is a barrier that stops oxygen and water reaching the iron