He did this through his famous gold foil experiment in 1911. In this experiment, he fired alpha particles (positively charged particles) at a thin sheet of gold foil. He observed that most of the alpha particles passed straight through the foil, but a small number were deflected at large angles, and some even bounced back.
This led Rutherford to conclude that:
* The atom is mostly empty space. The fact that most alpha particles passed straight through meant there was little in their path.
* A small, dense, positively charged region exists at the center of the atom. This region, which he called the nucleus, is responsible for deflecting the alpha particles. The positive charge in the nucleus also explained why some particles bounced back, as they were repelled by the strong positive charge.
Rutherford's discovery revolutionized our understanding of atomic structure, paving the way for the development of the modern atomic model.
