(i) Ernest Rutherford conducted an experiment to know the arrangement of the electrons inside the atom.
(ii) The experiment he conducted was the gold foil experiment, in which he made fast moving alpha particles to fall on a thin sheet of gold foil.
(iii) Rutherford expected the alpha particle to be deflected by the sub atomic particles in the atom but not by large angles because of the much heavier weight of the alpha particles of 4u.
(iv) The observations made by Rutherford during the experiment were different from what he expected. On basis of the observations and he concluded the structure and arrangement of the atom and the electrons and gave the nuclear model which had the following features:
(a) In every atom, there is a presence of the nucleus in the center of the atom which is positively charged and almost all the mass of the atom reside inside the nucleus.
(b) Electrons inside the atom revolved around the nucleus in a specified path called orbits.
(c) The radius of the nucleus is very small compared to the radius of the atom, so the size of the nucleus is very less as compared to the size of the atom. However, the nuclear model presented by him had some drawbacks which questioned the overall stability of the atom. The major drawbacks were:
(i) As the electrons revolve around the nucleus they would undergo acceleration and would radiate energy, so the revolution cannot be stable.
(ii) If the electrons radiate energy they would eventually fall into the nucleus which questioned the stability of the atom and the existence of the matter.
These were the major drawbacks that Rutherford could not explain which lead to the dismissal of the Rutherford nuclear model.
