Question

a) Write down the conclusions drawn by E. Rutherford from his α-particle scattering experiment.

b) What do you think would be the observation if the α-particle scattering experiment is carried out using a foil of a metal other than gold?
[3+2 = 5 Marks]

Answer 1

a) E. Rutherford concluded the following points through his α-particle scattering experiment:

(i) Most of the α-particles passed through the gold foil without getting deflected, indicating that most of the space inside an atom is empty.
[1 Mark]

(ii) Very few particles were deflected from their path, indicating that the positive charge of the atom occupies very little space.
[1 Mark]

(iii) A very small fraction of α-particles were deflected by 180°, indicating that all the positive charge and mass of the gold atom were concentrated in a very small volume within the atom.
[1 Mark]


b) If the α-particle scattering experiment is carried out using a foil of any metal as thin as gold foil, there would be no change in observation. But since other metals are not so malleable as gold, it is very difficult to obtain a thin foil from other metals. The gold foil was about 1000 atoms thick. If a thick foil is used, then more α-particles would bounce back, and a clear result would not be obtained.​
[2 Marks]