Eduqas GCSE Chemistry · Topic 6 — Reactivity series and extraction of metals
Mini-Lesson
Reactivity series & extraction of metals
This mini-lesson walks you through the whole of Eduqas Topic 6: how metals' reactions reveal their reactivity, displacement and redox, and how a metal's place in the reactivity series decides whether we extract it by carbon reduction or by electrolysis — with the blast furnace and aluminium as the worked examples.
Work through each screen, answer the questions as you go (some are wordy, some are equations) and collect ⭐ stars. Items marked Higher go beyond Foundation. Press Start when you're ready.
Reactions of metals
How reactive is a metal?
When a metal reacts it loses electrons to form a positive ion. The more easily it does this, the more reactive it is. Eduqas wants you to read reactivity off three kinds of reaction:
With water — only very reactive metals (e.g. potassium, sodium): metal + water → metal hydroxide + hydrogen.
With dilute acid — reactive metals fizz: metal + acid → salt + hydrogen.
With oxygen — almost all metals: metal + oxygen → metal oxide.
Read the clues: a metal that bubbles in cold water is very reactive; one that only fizzes in acid is moderately reactive; one that does neither (like gold) is very unreactive. Eduqas statement: reactivity is related to the metal's tendency to form its positive ion.
The reactivity series
Ranking the metals
Order the metals by their reactions and you get the reactivity series. The non-metals carbon and hydrogen are added as reference points — they decide how a metal is extracted (carbon) and what happens at the cathode (hydrogen).
Above carbon → too reactive for carbon reduction, so use electrolysis. Below carbon → reduce with carbon. Hydrogen marks the cathode rule in electrolysis.
Memory hook:Please Send Lions, Cats, Monkeys And Cute Zebras Into Hot Caves — K, Na, Li, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Au.
Sort it
Order them by reactivity
Tap each metal, then tap the box for whether it sits above or below carbon in the series.
⬆️ Above carbon (electrolysis)
⬇️ Below carbon (carbon reduction)
Displacement reactions
The bully rule
A more reactive metal will displace a less reactive one from its compound — it "kicks it out" because it holds onto electrons less tightly. Eduqas example: an iron nail in copper(II) chloride solution.
Fe + CuCl₂ → FeCl₂ + Cuiron is more reactive than copper, so iron takes copper's place
The nail gains a brown copper coat; the blue solution fades as colourless Fe²⁺ replaces blue Cu²⁺. A competition version is the thermit reaction: 2Al + Fe₂O₃ → 2Fe + Al₂O₃.Quick check
Will it react?
?A strip of zinc is placed in copper(II) sulfate solution. Using the reactivity series, what happens?
Oxidation & reduction · oxygen
Redox in terms of oxygen
The simplest definition Eduqas uses:
Oxidation = gain of oxygen.
Reduction = loss of oxygen.
In the thermit reaction and in the blast furnace, you must say which species is oxidised and which is reduced:
Watch out: the substance that loses oxygen is reduced, even though it sounds like it lost something. "Reduction = loss of oxygen" — the oxide is reduced down to the metal.
Higher · electrons
Redox in terms of electrons
At Higher tier, Eduqas wants redox in terms of electron transfer — used for displacement and electrolysis:
OIL RIGOxidation Is Loss · Reduction Is Gain (of electrons)
In the zinc + copper(II) displacement, write half-equations:
Half-equations
Zn → Zn²⁺ + 2e⁻ (loses electrons → oxidised)
Cu²⁺ + 2e⁻ → Cu (gains electrons → reduced)
Overall: Zn + Cu²⁺ → Zn²⁺ + Cu
OIL RIG vs oxygen: the two definitions agree. Losing electrons (oxidised) is the same idea as gaining oxygen — oxygen pulls electrons away from the metal.
Quick check · Higher
Oxidised or reduced?
?In the half-equation Fe²⁺ → Fe³⁺ + e⁻, the iron ion is…
Extraction methods
Reactivity decides the method
Most metals are found as ores (usually oxides). Getting the metal out means removing the oxygen — a reduction. Which method depends on where the metal sits relative to carbon:
Metal less reactive than carbon (zinc, iron, copper) → reduce its oxide with carbon. Cheaper.
Metal more reactive than carbon (aluminium, magnesium, sodium) → electrolysis of the molten compound. Carbon can't pull the oxygen off; only electricity can. More expensive (lots of energy).
Common error: students flip the rule. Remember: more reactive than carbon → electrolysis; less reactive than carbon → carbon reduction.
Sort it
Pick the extraction method
Tap the method used to extract each metal from its ore.
Iron · blast furnace
Extracting iron
Iron is less reactive than carbon, so it is reduced in the blast furnace. It's so hot that carbon monoxide does most of the reducing:
Fe₂O₃ + 3CO → 2Fe + 3CO₂iron(III) oxide is reduced (loses O); carbon monoxide is oxidised (gains O)
Limestone (CaCO₃) removes acidic (sandy) impurities, forming molten slag that floats on the iron — an acid/base reaction.Aluminium · electrolysis
Extracting aluminium
Aluminium is more reactive than carbon, so it must be extracted by electrolysis of its molten oxide (from the ore bauxite). Aluminium oxide melts at over 2000 °C, so it is dissolved in molten cryolite to lower the temperature and save energy.
Al³⁺ is reduced to Al at the cathode. Oxygen forms at the carbon anodes and reacts with them, so the anodes burn away and must be replaced — adding to the cost.
Eduqas also expects you to evaluate newer methods — phytoextraction (plants absorb metal compounds; burn the plants for ash) and bacterial extraction / bioleaching (bacteria produce metal-rich leachate). They're slow but useful for low-grade ores.
Quick check
Which method?
?A metal sits above carbon in the reactivity series. Which extraction method must be used, and why?
Electrolysis · molten
What happens at the electrodes
When an ionic compound is molten, its ions are free to move. Pass a current and they are discharged:
Cathode (−): attracts positive metal ions → the metal forms (reduction, gain of electrons).
Anode (+): attracts negative ions → the non-metal forms (oxidation, loss of electrons).
Eduqas example — molten lead(II) bromide:
PbBr₂ → Pb + Br₂Pb²⁺ → Pb at cathode (gains e⁻) · 2Br⁻ → Br₂ at anode (loses e⁻)
Aqueous twist (Higher): in solutions there are also H⁺ and OH⁻ from water, so competing reactions occur — at the cathode, hydrogen forms unless the metal is less reactive than hydrogen; at the anode, a halogen forms if a halide is present, otherwise oxygen.
Calculate · Higher
Balancing a half-equation
1Aluminium is deposited at the cathode: Al³⁺ + n e⁻ → Al. How many electrons, n, are needed to balance this half-equation?
e⁻
Hint: the charge must balance. Al³⁺ has a 3+ charge, so it needs 3 electrons to become neutral Al.
Quick check
Spot the reduction
?In the blast furnace: Fe₂O₃ + 3CO → 2Fe + 3CO₂. Which species is reduced (in terms of oxygen)?
Properties & uses
Choosing the right metal
Eduqas wants you to link properties to uses for four metals: