Class 10 Metals and Non-metals — Using the Reactivity Series
Most students memorise the reactivity series and then still cannot answer the question "will this reaction happen?". The series is not a list to recite — it is a prediction tool. Learn the order once, then learn the four things it predicts, and a large part of the Metals and Non-metals chapter answers itself: reactions with water, reactions with acids, displacement from salt solutions, and how each metal is extracted from its ore.
The series, in order
Potassium at the top is the most reactive; gold at the bottom is the least. Hydrogen is not a metal, but it is placed in the list because its position decides which metals react with dilute acids. Everything above hydrogen displaces it from a dilute acid; everything below does not.
Prediction 1 — reaction with water
How vigorously a metal reacts with water falls steadily as you go down the series.
| Metal | Behaviour with water | Equation |
|---|---|---|
| K, Na | React violently with cold water; sodium's reaction is so exothermic that the hydrogen catches fire | 2Na + 2H₂O → 2NaOH + H₂ |
| Ca | Reacts with cold water, less violently; the metal floats as bubbles stick to it | Ca + 2H₂O → Ca(OH)₂ + H₂ |
| Mg | No reaction with cold water; reacts with hot water | Mg + 2H₂O → Mg(OH)₂ + H₂ |
| Al, Zn, Fe | React only with steam, and give the oxide, not the hydroxide | 2Al + 3H₂O → Al₂O₃ + 3H₂ Zn + H₂O → ZnO + H₂ 3Fe + 4H₂O → Fe₃O₄ + 4H₂ |
| Cu, Ag, Au | No reaction with water in any form | — |
Notice the pattern change halfway down: the very reactive metals give a hydroxide, while aluminium, zinc and iron give an oxide with steam. Writing Fe(OH)₂ for the steam reaction is a common lost mark.
Prediction 2 — reaction with dilute acids
A metal above hydrogen displaces hydrogen gas from a dilute acid. A metal below hydrogen cannot.
Zn + 2HCl → ZnCl₂ + H₂ · Fe + 2HCl → FeCl₂ + H₂ · 2Al + 6HCl → 2AlCl₃ + 3H₂
Copper, silver and gold sit below hydrogen, so they give no reaction with dilute hydrochloric or dilute sulphuric acid. There is one important exception to the general rule: nitric acid usually does not give hydrogen gas with metals, because it is a strong oxidising agent and oxidises the hydrogen produced to water. Magnesium and manganese with very dilute nitric acid are the two cases where hydrogen is evolved.
Aluminium and zinc are also amphoteric — their oxides react with both acids and bases, and the metals themselves react with hot alkali:
Zn + 2NaOH → Na₂ZnO₂ + H₂ · Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O · Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O
Prediction 3 — displacement from salt solutions
Zinc in copper sulphate solution:
Zn + CuSO₄ → ZnSO₄ + Cu
Zinc is above copper, so the reaction happens. What you actually see: the blue colour of CuSO₄ fades to colourless, and a reddish-brown deposit of copper appears on the zinc.
Iron in copper sulphate solution:
Fe + CuSO₄ → FeSO₄ + Cu
Iron is also above copper. The blue solution turns pale green (iron(II) sulphate) and copper deposits on the iron nail. This is the classic Class 10 practical.
Copper in zinc sulphate solution:
Cu + ZnSO₄ → no reaction, because copper is below zinc. Nothing changes: the solution stays colourless and the copper stays copper.
Worked example — reading an experiment and building the order
Four metals P, Q, R and S were tested. The results were:
- Q displaces P from a solution of P sulphate.
- R does not displace Q from a solution of Q sulphate.
- S displaces R from a solution of R sulphate.
- P displaces R from a solution of R sulphate.
- Q displaces S from a solution of S sulphate.
- S does not displace P from a solution of P sulphate.
- Only P and Q give hydrogen gas with dilute hydrochloric acid.
Reasoning, one clue at a time:
From (1): Q > P.
From (2): R < Q — consistent, no new information about P yet.
From (4): P > R.
From (3): S > R.
From (5): Q > S.
From (6): S < P.
Putting these together: Q is above P (1); P is above S (6); S is above R (3).
Order, most reactive first: Q > P > S > R.
Check it against every clue: (2) R < Q ✓, (4) P > R ✓, (5) Q > S ✓. All consistent.
And where is hydrogen? From (7), only P and Q release hydrogen from dilute acid, so hydrogen sits between P and S: Q > P > [H] > S > R.
Prediction 4 — how the metal is extracted
A metal's position decides how much energy is needed to pull it out of its ore, so the series splits neatly into three extraction groups.
| Group | Metals | Method | Example |
|---|---|---|---|
| Most reactive | K, Na, Ca, Mg, Al | Electrolysis of the molten salt or oxide — no chemical reducing agent is strong enough | Molten NaCl → Na at the cathode, Cl₂ at the anode |
| Moderately reactive | Zn, Fe, Pb, Cu | Convert ore to the oxide (roasting a sulphide, calcining a carbonate), then reduce with carbon | 2ZnS + 3O₂ → 2ZnO + 2SO₂; ZnCO₃ → ZnO + CO₂; ZnO + C → Zn + CO |
| Least reactive | Hg, Ag, Au | Often found free; sulphide ores need only heating | 2HgS + 3O₂ → 2HgO + 2SO₂, then 2HgO → 2Hg + O₂ |
Aluminium is a good reducing agent precisely because it is high in the series. In the thermite reaction it reduces iron(III) oxide, releasing so much heat that the iron comes out molten and can weld a cracked railway track:
Count the atoms to confirm it is balanced: Fe 2 = 2, O 3 = 3, Al 2 = 2. ✓
What about the non-metals?
Non-metals behave in the opposite way, and the contrast is examined directly.
| Property | Metals | Non-metals |
|---|---|---|
| Electrons | Lose electrons — reducing agents | Gain electrons — oxidising agents |
| Oxide | Basic (some amphoteric: Al₂O₃, ZnO) | Acidic or neutral |
| With dilute acid | Metals above H give H₂ | No reaction — a non-metal cannot donate electrons to H⁺ |
| Physical | Malleable, ductile, conduct heat and electricity, sonorous | Brittle, poor conductors (graphite is the exception) |
When a metal high in the series meets a non-metal, the transfer of electrons is complete and an ionic compound results — for example 2Na + Cl₂ → 2NaCl, in which sodium loses one electron and chlorine gains one. Ionic compounds have high melting points and conduct electricity when molten or dissolved, but not as solids.
Gold and platinum resist even concentrated acids individually; they dissolve only in aqua regia, a freshly prepared 3 : 1 mixture by volume of concentrated hydrochloric acid and concentrated nitric acid.
Mistakes that lose marks
- Writing a hydroxide for the steam reaction. Al, Zn and Fe give the oxide with steam — Al₂O₃, ZnO, Fe₃O₄ — not the hydroxide.
- Expecting hydrogen gas from nitric acid. HNO₃ is an oxidising acid, so hydrogen is normally not released. Only Mg and Mn with very dilute HNO₃ give H₂.
- Saying copper reacts with dilute HCl. Copper is below hydrogen, so there is no reaction at all.
- Writing a displacement the wrong way round. Cu + ZnSO₄ never happens; only Zn + CuSO₄ does.
- Leaving equations unbalanced. "Fe + H₂O → Fe₃O₄ + H₂" is worth fewer marks than the balanced 3Fe + 4H₂O → Fe₃O₄ + 4H₂. Always count atoms on both sides before you move on.
- Forgetting that Al and Zn are amphoteric. Their oxides react with NaOH as well as with acid — a standard two-mark question.
- Confusing roasting and calcination. Roasting heats a sulphide ore in excess air; calcination heats a carbonate ore in limited air or none.
Where this is examined
| Board / exam | Typical question |
|---|---|
| CBSE Class 10 | Predict and balance displacement reactions; arrange metals in order from experimental observations; explain the extraction method for a named metal |
| ICSE Class 10 | Reactivity series with reasoning, activity series applied to electrolysis and to metallurgy |
| Class 10 practical | Iron nail in copper sulphate solution — colour change and deposit |
| Class 11–12 (later) | The same order reappears quantitatively as the electrochemical series of standard electrode potentials |
Balance every equation before you write it in the answer sheet. The Chemical Equation Balancer takes an unbalanced equation such as Fe + H2O = Fe3O4 + H2 or Fe2O3 + Al = Al2O3 + Fe and returns the correct coefficients, so you can check the displacement, steam and thermite equations in this article for yourself.
Open the Chemical Equation Balancer →Class 10 is the year the chemistry base is either built or missed. ABC Chemistry runs Class 11–12 chemistry coaching at its Gurugram centre and online classes across India — see abcchemistry.in. In Delhi, Noida and Gurgaon, one-to-one home tuition is available through delhihometutor.com.