Rutherford's alpha particle scattering experiment led to the nuclear model of the atom. Describe the key conclusions Rutherford drew from the results of this experiment, and state the evidence from the experiment that supports each conclusion.

Cambridge International IGCSE Physics (0625) — 5.1 The nuclear model of the atom · Describe · 4 marks · View as Markdown

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

In Rutherford's experiment, a beam of alpha particles was directed at a thin gold foil. Most alpha particles passed straight through, some were deflected at small angles, and a very small number were deflected straight back.

Model answer (4 marks)

1. The atom is mostly empty space – most alpha particles passed straight through the foil.
2. The nucleus is positively charged – alpha particles were repelled/deflected by the nucleus.
3. The nucleus is very small – only a very small number of alpha particles were deflected straight back.
4. The nucleus contains most of the mass of the atom – the large deflections of the few alpha particles that were scattered back show the mass is concentrated in a tiny region.

Examiner tips

  • Use the exact wording from the mark scheme (e.g. ‘mostly empty space’, ‘positively charged’, ‘very small’, ‘contains most of the mass’).
  • Link each conclusion directly to the experimental evidence in a single sentence.
  • Keep each point short – 1–2 lines – to fit the 4‑mark allocation.

Common mistakes

  • Mixing up the evidence – e.g. saying the small number of back‑scattered particles prove the atom is empty.
  • Using vague terms like ‘tiny’ instead of ‘very small’.
  • Omitting the link between the deflection and the positive charge of the nucleus.

Mark scheme (4 marks)

  1. The atom is mostly empty space, supported by most alpha particles passing straight through the foil.
  2. The nucleus is positively charged, supported by alpha particles being repelled/deflected.
  3. The nucleus is very small, supported by only a very small number of alpha particles being deflected straight back.
  4. The nucleus contains most of the mass of the atom, supported by alpha particles being deflected straight back.

Key terms in this question

nuclear model · alpha particle

Related

More The nuclear model of the atom questions

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