The nuclear atom and alpha scatteringEdexcel A-Level Physics: Mind map

Exam questions on The nuclear atom and alpha scattering

1. A neutral atom of copper-63 is written ⁶³₂₉Cu.
   Another isotope of copper has a nucleon number of 65. State the number of protons and the number of neutrons in its nucleus, and explain why it is still copper.2 marks
2. In the Geiger–Marsden experiment a narrow beam of alpha particles in an evacuated chamber was directed at a very thin gold foil. A detector that could be moved round the foil counted the alpha particles scattered at different angles. Most alpha particles passed through the foil with little or no deflection, but a very small number were deflected through large angles.
   Explain why the gold foil had to be very thin.2 marks
3. In one run of an alpha-scattering experiment with a thin gold foil, a total of 4.0 × 10⁵ alpha particles were counted. About 1 in 8000 of them was scattered through an angle of more than 90°.
   Calculate the number of alpha particles scattered through more than 90°, and state what such a small fraction shows about the nucleus.3 marks