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       Rutherford's Alpha Particle Scattering Experiment

In his experiment Rutherford bombarded a thin gold foil with the fast moving alpha particles. He took a gold foil about 1000 atoms thick and a doubly charged helium ions.

             Observation

In his experiment Rutherford made the following observation:

• Most of the \[\alpha \] particles passed straight through the gold foil.
• Few of the \[\alpha \] particles were deflected through a small angles as it passes through the gold foil.
• Very few a particles bounces back in the same direction from which they came.

            Conclusion

On the basis of his experiment and observation he made the following conclusion:

• There is large empty space in the atom.
• The nucleus of the atom is positively charged.
• The nucleus of the atom is densely packed.

            Rutherford Model of Atom

On the basis of the above experiment he proposed the following model of an atom. According to him atom consists of positively charged nucleus where the entire mass is supposed to be concentrated. The electron revolve around the nucleus in a well defined orbit and size of the nucleus is very small as compared to the size of the atom.

           Drawback of Rutherford Model of Atom

Followings are the drawback of Rutherford model of an atom:

The orbital revolution of the electron is not expected to be stable. Any particle in a circular orbit would undergo acceleration. During acceleration, charged particles would radiate energy. Thus, revolving electrons would lose energy and finally fall into nucleus. If they were so, the atom would be highly unstable and hence matter would not exist in the form that we know. But this does not happen and we know that atoms are quite stable.