Question

what is rutherford's model of an atom?

Answer 1

Ernst Rutherford bombarded thin sheets of gold foil with fast moving alpha particles.

But what are these alpha particles?

Alpha particles are doubly charged helium ions having a mass of 4u.

But why choose a gold foil?

Rutherford selected a gold foil because he wanted a layer as thin as possible. And this was possible by gold foil which was about 1000 atoms thick

Rutherford made the following observations :
1) Most of the fast moving alpha particles passed straight through the gold foil.
2) Some if the alpha particles were deflected by the foil by small angles.
3) Very few alpha particles (one out of 12,000) appeared to rebound.

Rutherford concluded that ---
1) Most of the space inside the atom is empty because most of the alpha particles passed through the gold foil without getting deflected.
2) Very few particles were deflected from their path which indicates that positive charge of the atom occupies a very little space inside atom.
3) A very small fraction of alpha particles were completely deflected that indicates that all the positive charges and mass of the atom were concentrated in à very small volume within the atom.

Rutherford's model of atom gives us that ---
1) There is highly sensed positively charged centre in an atom called nucleus.Almost all the mass of atom is concentrated here.
2) The electrons revolve the nucleus in well defined orbits.
3) The size of the nucleus is very small compared to the size of atom.


Now the question is how does Rutherford's model of atom looks?

Well, Rutherford suggested that his model of atom was similar to our solar system. The planets revolve around the Sun. Similarly, in an atom the electrons are revolving around the nucleus. So he called these electrons planetary electrons.

Answer 2

Rutherford's model of atom is an experimental output that came after scattering alpha particles for gold foil.