Scientists use results from two investigations to decide whether atomic models should be changed.
An early nuclear model stated that electrons surround a nucleus but did not describe how the electrons are arranged.
A heated sample of hydrogen emits light at several wavelengths. In 1913, a scientist proposed a new model of the atom and used it to calculate the wavelengths that heated hydrogen should emit. The wavelengths are recorded to the nearest nanometre.
| Measured wavelength (nm) | Wavelength calculated using the new model (nm) |
|---|---|
| 434 | 434 |
| 486 | 486 |
| 656 | 656 |
Explain how these results provide evidence for changing the early nuclear model.
At a later stage, a model stated that the nucleus contained only protons. Scientists obtained the following data for one type of nucleus.
| Quantity | Value |
|---|---|
| Measured relative positive charge of the nucleus | +8 |
| Measured relative mass of the nucleus | 17 |
| Relative charge of one proton | +1 |
| Relative mass of one proton | 1 |
Predict how the model of the nucleus should be changed. Justify your answer using the data.
101 exam-style questions on OCR GCSE Chemistry 1.2 Atomic structure, covering 1.2.1 Development of the atomic model, 1.2.2 The nuclear model and the size of atoms, and 1.2.3 Subatomic particles in atoms and ions. Each one has a worked solution and a mark scheme showing where the marks go.