The shape of the lesson
By the end of the lesson, learners can
- Building the series: The same three tests put the metals in order.
- Displacement reactions: Put metals into solutions of other metals' salts in the simulator.
- Order: K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au.
- Displacement: a more reactive metal pushes out a less reactive one.
- Extended: more reactive = forms positive ions more readily.
- Aluminium: protected by its oxide layer.
One picture every idea returns to
The reactivity series, from most to least reactive, is: potassium, sodium, calcium, magnesium, aluminium, (carbon), zinc, iron, (hydrogen), copper, silver, gold. It is worked out from reactions with cold water, steam and dilute acids. A more reactive metal displaces a less reactive metal from a solution of its salt. Extended: the more reactive the metal, the more easily it loses electrons to form positive ions. Aluminium appears unreactive because of its protective oxide layer.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, A league table of metals.. Put metals in water, steam and acid and rank them by how fast they react. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 17 min | Teach and check: Building the series | The same three tests put the metals in order. | Whole class, then pairs |
| 17 to 30 min | Teach and check: Displacement reactions | Put metals into solutions of other metals' salts in the simulator. Project tab 2 of the lab (Electrochemistry lab, electron transfer) and let a student drive it while the class predicts. | Think-Pair-Share |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 14 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Displacement reactions, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Think-Pair-Share
Pose the question, give thirty seconds of silent thinking, then a minute to compare with a partner before a few pairs share with the class. The silent minute is the part that cannot be cut.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| Aluminium is high in the series but often seems unreactive, for example it does not react with water. | That is because its surface is sealed by a layer of aluminium oxide, not because it is low in the series. Remove the layer and it reacts vigorously. |
The reactivity series: worksheet
6 questions, 14 marks. Written in the style of the papers; no past paper question is reproduced.
Metals W, X and Y are added to dilute hydrochloric acid. W fizzes rapidly, X does not react, and Y fizzes slowly. Put them in order of reactivity, most reactive first, and suggest which could be copper.
Zinc is added to copper(II) sulfate solution. Describe two observations and write the word equation.
Predict whether a reaction occurs, and name any products: (a) iron + silver nitrate solution, (b) copper + magnesium sulfate solution.
(Extended) Write the ionic equation for the reaction of iron with copper(II) sulfate solution to form iron(II) ions.
(Extended) Explain, in terms of electrons, why zinc displaces copper from copper(II) sulfate solution.
Explain why aluminium saucepans do not react with water although aluminium is a reactive metal.
Answer key and marking notes
- W, Y, X.
- X could be copper (no reaction with dilute acid).
- (W could be magnesium; Y could be iron or zinc.)
- The blue colour of the solution fades.
- A pink-brown solid (copper) forms on the zinc (and the mixture gets warm).
- zinc + copper(II) sulfate → zinc sulfate + copper
- (a) yes: iron nitrate and silver.
- (b) no reaction: copper is less reactive than magnesium.
- Fe(s) + Cu2+(aq) → Fe2+(aq) + Cu(s)
- One mark for the species, one for balancing and state symbols.
- Zinc is more reactive, so it loses electrons more readily than copper.
- Zinc atoms give electrons to Cu2+ ions, forming Zn2+ ions and copper atoms.
- The surface of aluminium is covered by a thin layer of aluminium oxide.
- This layer is unreactive and stops water reaching the metal.
7 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
Three metals, P, Q and R, are each placed in solutions of the nitrates of the other two metals. A tick shows that a metal coating formed.
| Metal | P nitrate | Q nitrate | R nitrate |
|---|---|---|---|
| P | – | ✓ | ✓ |
| Q | ✗ | – | ✗ |
| R | ✗ | ✓ | – |
- AP, R, Q
- BQ, R, P
- CP, Q, R
- DR, P, Q
A mixture of aluminium powder and iron(III) oxide is ignited. The reaction is very exothermic and molten iron is produced. What does this reaction show?
- Aaluminium is more reactive than iron
- Biron is more reactive than aluminium
- Ciron(III) oxide decomposes on its own when heated
- Daluminium is below carbon in the reactivity series
Which metal reacts with dilute hydrochloric acid but shows no reaction with cold water?
- Azinc
- Bsodium
- Ccopper
- Dsilver
Metal M displaces copper from copper(II) sulfate solution but does not displace zinc from zinc sulfate solution. Which statement about M is correct?
- AM atoms lose electrons more readily than copper atoms but less readily than zinc atoms
- BM atoms lose electrons more readily than zinc atoms
- CM atoms gain electrons more readily than copper atoms
- DM forms negative ions more readily than copper does
A copper wire is placed in silver nitrate solution. Silver crystals grow on the wire and the solution turns blue. Which is the ionic equation?
- ACu(s) + 2Ag+(aq) → Cu2+(aq) + 2Ag(s)
- BCu(s) + Ag+(aq) → Cu2+(aq) + Ag(s)
- CCu2+(aq) + 2Ag(s) → Cu(s) + 2Ag+(aq)
- DCu(s) + 2NO3−(aq) → Cu(NO3)2(aq)
Zinc powder is added to copper(II) sulfate solution: Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s). Which species is oxidised?
- Azinc atoms
- Bcopper(II) ions
- Csulfate ions
- Dcopper atoms
Magnesium displaces silver from silver nitrate solution: Mg(s) + 2Ag+(aq) → Mg2+(aq) + 2Ag(s). How many electrons are transferred for each magnesium atom that reacts?
- A2
- B1
- C3
- D4
Quiz key
P displaces both Q and R, so P is the most reactive. R displaces Q but not P, so R is in the middle. Q displaces neither, so Q is the least reactive: P, R, Q. The order Q, R, P is the right sequence reversed. Placing Q above R ignores the fact that R displaces Q, and placing R first ignores the fact that P displaces R.
The equation is 2Al + Fe2O3 → Al2O3 + 2Fe. Aluminium takes the oxygen from iron(III) oxide, which is only possible because aluminium is more reactive than iron: a displacement reaction involving oxides. If iron were more reactive, no reaction would occur. Iron(III) oxide does not decompose into iron simply on heating; the aluminium is needed. Aluminium is above carbon, not below it.
Zinc is above hydrogen, so it reacts with dilute acids to give hydrogen, but it is not reactive enough to react with cold water (it reacts only with steam when hot). Sodium reacts with both cold water and acid (dangerously with acid). Copper and silver are below hydrogen, so they react with neither.
M is more reactive than copper but less reactive than zinc, so it sits between them (iron would fit). A more reactive metal loses electrons to form positive ions more readily, so M loses electrons more readily than copper but less readily than zinc. If M lost electrons more readily than zinc it would displace zinc. Metals do not gain electrons or form negative ions in these reactions; they lose electrons.
Each copper atom loses two electrons to form Cu2+ (the blue colour), and each Ag+ ion gains one electron, so two silver ions are needed per copper atom: Cu + 2Ag+ → Cu2+ + 2Ag. With only one Ag+ the charges do not balance (1+ on the left, 2+ on the right). The reversed equation would need silver to be more reactive than copper, which it is not. Nitrate ions are spectators and do not appear in the ionic equation.
Zinc atoms lose two electrons each to become Zn2+ ions, so zinc is oxidised. The copper(II) ions gain those electrons and are reduced to copper atoms. Sulfate ions are unchanged spectators. Copper atoms are a product of the reaction, formed by reduction, so they are not oxidised.
A magnesium atom (charge 0) becomes Mg2+, so it loses 2 electrons. These are accepted by two Ag+ ions, one electron each. The answer 1 is the number gained by each silver ion, not the number lost by magnesium. Values of 3 or 4 do not match any change of charge in the equation.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.