Geiger and Marsden fired alpha particles at a very thin sheet of gold foil. Alpha particles are positively charged and have a relative mass of 4.
A detector counted the number of alpha particles deflected through different angles.
The table shows a set of results.
| Angle of deflection (degrees) | Number of alpha particles detected per minute |
|---|---|
| 0 to 10 | 98 500 |
| 10 to 30 | 1400 |
| 30 to 90 | 95 |
| 90 to 180 | 5 |
Calculate the percentage of the alpha particles that were deflected by more than 90 degrees.
Suggest why the gold foil had to be very thin.
Explain how these results show that the "plum pudding" model of the atom is wrong, and how they support the nuclear model.
Use the data in the table.
51 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.