J.J Thomson contributed massively to the model of the atom and the modern day theory. His work involved the use of cathode ray tubes and identifying a particle lighter than the atom itself, the electron.
The work of J.J Thomson’s student, Ernest Rutherford, led to the discovery of the Proton. Working with alpha particles fired at a piece of gold foil it was observed that instead of passing straight through it was scattered. Suggesting there was something large in the centre of the atom.