Discovery of Proton

Discovery of Proton:

In 1909, Rutherford discovered proton in his famous gold foil experiment.

GOLD FOIL EXPERIMENT

In his gold foil experiment, Rutherford bombarded a beam of alpha particles on an ultrathin gold foil and then detected the scattered alpha particles in zinc sulfide (ZnS) screen.

Results

1.  Most of the particles pass through the foil without any deflection.

2.  Some of the alpha particles deflect at small angle.

3.  Very few even bounce back (1 in 20,000).

Conclusion

Based on his observations, Rutherford proposed the following structural features of an atom:

1.  Most of the atom’s mass and its entire positive charge are confined in a small core, called nucleus. The positively charged particle is called proton.

2.  Most of the volume of an atom is empty space.

3.  The number of negatively charged electrons dispersed outside the nucleus is same as number of positively charge in the nucleus. It explains the overall electrical neutrality of an atom.

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