Describe the differences between an element, a compound, and a mixture. Include one example of each in your answer.

Cambridge International IGCSE Chemistry (0620) — 2.1 Elements, compounds and mixtures · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

An element is a substance that contains only one type of atom and cannot be broken down into simpler substances by chemical means. For example, iron (Fe). A compound is a substance made up of two or more different elements chemically combined in fixed proportions; for example, water (H₂O). A mixture is a combination of two or more substances that are not chemically bonded together and can be separated by physical methods; for example, salt water.

Examiner tips

  • Use the exact definitions from the mark scheme; include the key phrases "cannot be broken down" and "fixed proportions".
  • Give one clear example for each type of substance.
  • Keep the answer concise – 4 marks only.
  • Use UK spelling (e.g. "chemistry").

Common mistakes

  • Confusing a compound with a mixture by saying the elements are simply mixed rather than chemically bonded.
  • Giving an example that is actually a mixture (e.g. saying "salt" instead of "sodium chloride").
  • Using vague terms like "substance" without specifying the type.

Mark scheme (4 marks)

  1. An element contains only one type of atom / is a substance that cannot be broken down into simpler substances by chemical means
  2. A compound contains two or more different elements chemically combined / joined together in fixed proportions
  3. A mixture contains two or more substances NOT chemically combined / substances can be separated by physical methods
  4. One correct example of each: element (e.g. iron / oxygen / carbon), compound (e.g. water / sodium chloride / carbon dioxide), mixture (e.g. air / salt water / sand and iron filings)

Key terms in this question

element · compound · mixture

Related

More Elements, compounds and mixtures questions

▶ Try answering this question with AI marking (free) →