As we know in the gold foil experienment he passes alpha particle thought 3 gold atom ....and he found that most of the spaces was empty so most of rays deflected most of rays passes in straight way only a few can deflected with a greater angle. .....from this data he conclude that nucleus is about 10^5 time lesser than the radius of atom..........and from this experienment he found nucleus .

Rutherford's Gold Foil Experiment

Rutherford's gold foil experiment, also known as the Geiger-Marsden experiment, was conducted by physicist Ernest Rutherford in 1909. The purpose of this experiment was to investigate the structure of atoms and to test the prevailing model at the time, known as the Thomson model or the plum pudding model.

The Experiment Setup

In the experiment, Rutherford and his team fired alpha particles (positively charged particles) at a thin sheet of gold foil. They expected the alpha particles to pass straight through the foil or be slightly deflected, as predicted by the Thomson model.

The Unexpected Results

However, Rutherford observed some unexpected results during the experiment. Most of the alpha particles passed straight through the gold foil, as expected. However, a small percentage of the alpha particles were deflected at large angles, and a very few even bounced back in the direction from which they came. This observation was contrary to the predictions of the Thomson model.

Conclusions from the Experiment

Based on these unexpected results, Rutherford drew several important conclusions:

1. The atom is mostly empty space: The fact that most of the alpha particles passed straight through the gold foil without any deflection indicated that the atom is mostly empty space. If the atom were a solid mass as suggested by the Thomson model, the alpha particles would not have been able to pass through the foil without significant deflection.

2. The nucleus is small and positively charged: The deflection and scattering of alpha particles at large angles and some even bouncing back indicated the presence of a small, dense, and positively charged region within the atom. Rutherford called this region the "nucleus." The positive charge of the nucleus was responsible for repelling the positively charged alpha particles.

3. Electrons revolve around the nucleus: Rutherford's experiment did not directly provide evidence about the location or behavior of electrons within the atom. However, based on his observations, Rutherford proposed that electrons revolve around the nucleus in specific orbits or energy levels. This model came to be known as the Rutherford model of the atom.

Summary

In conclusion, Rutherford's gold foil experiment provided evidence that the atom is mostly empty space, that the nucleus is small and positively charged, and that electrons revolve around the nucleus. These findings marked a significant shift in our understanding of atomic structure and laid the foundation for further discoveries in the field of nuclear physics.