Describe the structure of an atom in terms of the particles it contains, including where those particles are found and their relative charges.

Edexcel GCSE Chemistry (1CH0) — 1.3 Atomic structure · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

The nucleus is at the centre of the atom and contains protons and neutrons.
Electrons are found in shells or energy levels surrounding the nucleus.
Protons have a relative charge of +1.
Electrons have a relative charge of −1 and neutrons are neutral.

Examiner tips

Use the exact wording ‘nucleus’, ‘protons’, ‘neutrons’, ‘electrons’, ‘shells/energy levels’, ‘relative charge’. Show the charge values (+1, −1, neutral) as separate points. Keep the answer short – one sentence per point – to fit the 4‑mark structure.

Common mistakes

Writing ‘electrons are in the nucleus’ instead of shells. Omitting the charge of neutrons or giving the wrong sign for electrons. Using vague terms like ‘particles’ without specifying protons, neutrons, electrons.

Mark scheme (4 marks)

The nucleus is at the centre of the atom and contains protons and neutrons
Electrons are found in shells / energy levels surrounding the nucleus
Protons have a relative charge of +1
Electrons have a relative charge of −1 AND neutrons have no charge / are neutral

Key terms in this question

relative charge