A student wrote this account of the development of the atomic model.
| Stage | Proposed account |
|---|---|
| 1 | Atoms were pictured as tiny solid spheres that could not be divided. |
| 2 | Alpha-scattering evidence led to a nuclear model in which electrons occupied fixed energy levels. |
| 3 | Thomson discovered the electron and proposed the plum pudding model. |
| 4 | Bohr made a further proposal that was accepted because his theoretical calculations agreed with experimental evidence. |
| 5 | Chadwick found evidence for the neutron, leading to the modern picture of the nucleus. |
The account contains two errors.
Identify each error and give the correction.
93 exam-style questions on AQA GCSE Chemistry 1.1 A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes, covering 1.1.1a Atoms, elements and compounds, 1.1.1b Half equations and ionic equations, 1.1.2 Mixtures, 1.1.3 The development of the model of the atom (common content with physics), 1.1.4 Relative electrical charges of subatomic particles, 1.1.5 Size and mass of atoms, 1.1.6 Relative atomic mass, and 1.1.7 Electronic structure. Each one has a worked solution and a mark scheme showing where the marks go.