The structure of atoms was deduced in the early 1900s by Rutherford and his co-workers from the scattering of alpha-particles by a very thin sheet of gold.
Rutherford assumed that the scattering of the alpha-particles was due to electrostatic forces.
Fig. 23 shows a detector used to record the number N of alpha-particles scattered through an angle θ.
Fig. 23
At θ = 0°, N was too large to be measured. The table below summarises some of the collected data.
θ / ° | lg (N) |
|---|---|
150 | 1.5 |
75 | 2.3 |
60 | 2.7 |
30 | 3.9 |
15 | 5.1 |
0 | N too large |
i) Show that the number of alpha-particles scattered through 15° is about 4000 times more than those scattered through 150°.
[1]
ii) Use the evidence from the table to explain the structure of the atom.
[3]
A proton with kinetic energy 0.52 MeV is travelling directly towards a stationary nucleus of cobalt-59 (
) in a head-on collision.
i) Explain what happens to the electric potential energy of the proton-nucleus system.
[1]
ii) Calculate the minimum distance R between the proton and cobalt nucleus.
R = ..................................................... m [3]
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