Question

How did Rutherford’s gold foil experiment differ from his expectations?

Answer 1

The basic concept of chemistry which tells us about the Rutherford’s gold foil experiment where he proposed his model with the four postulates and the experiments consisted of scattering of $\alpha$ particle and his expectations which differed is related with the deflection of this particle which leads to the correct answer.

Complete step by step answer:
- In the very lower classes of chemistry, we have studied the various atomic models proposed by the scientists to explain the basis of atoms.
Let us now see what Rutherford’s atomic model says and how did the result differ from his expectations.
- Rutherford carried out an alpha scattering experiment which is popularly known as the gold foil experiment to determine the structure of an atom.
- In this experiment a stream of high energy- particles were made to hit a thin gold foil which is of the thickness of about 100 nm and these scattered $\alpha$- particles were detected as the tiny flashes of light when they hit the photosensitive $ZnS$ screen.
- He expected that these $\alpha$- particles will pass through the gold foil with slight deflection on the angles as this particle is weakly positively charged.
- But in this experiment that he carried out, some of the $\alpha$- particles not only deflected to the larger angles but also some of them bounced back with the large angle scattering.
Thus, this fact differs from Rutherford’s expectations and he concluded that in every atom there is some heavy body at the centre and this central body is extremely small in size.

Note: Note that the alpha particles are positively charged particles and are deflected but not attracted by the central body and therefore Rutherford concluded that the heavy body at the centre of the atom has the positive charge.