Copper can be found as a native metal in the Earth's crust, whereas aluminium is always found combined with other elements in ores. Explain why copper can exist as a native metal whilst aluminium cannot, and state the method used to extract aluminium from its ore.

Eduqas GCSE Chemistry — 2.3 Metals and their extraction · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Copper is relatively unreactive and lies lower in the reactivity series, so it does not readily combine with other elements and can exist as a native metal. Aluminium is very reactive and high in the reactivity series; it readily combines with oxygen and other elements, so it is only found as a compound. Aluminium is extracted by electrolysis of its molten oxide (Al₂O₃). Electrolysis is required because aluminium is too reactive for reduction by carbon – carbon cannot displace aluminium from its oxide.

Examiner tips

  • Use the reactivity‑series explanation for both metals; link copper’s low reactivity to native occurrence and aluminium’s high reactivity to its compound form.
  • State the extraction method (electrolysis of molten Al₂O₃) and why it is necessary (carbon cannot reduce aluminium).
  • Keep the answer concise – 4 marks, so one sentence per point.
  • Use UK spelling (electrolysis).

Common mistakes

  • Confusing the reactivity series (e.g., saying copper is highly reactive).
  • Failing to mention that aluminium is extracted by electrolysis of molten oxide.
  • Using the wrong extraction method (e.g., smelting with carbon).

Mark scheme (4 marks)

  1. Copper is (relatively) unreactive / low in the reactivity series, so it does not readily combine with other elements
  2. Aluminium is (very) reactive / high in the reactivity series, so it readily combines with other elements / is found as a compound
  3. Aluminium is extracted by electrolysis (of its molten ore/aluminium oxide)
  4. Electrolysis is needed because aluminium is too reactive to be reduced by carbon / carbon cannot displace aluminium

Key terms in this question

native metal · ore

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