Thomson's atomic model was proposed in 1904 and was called the plum pudding model. It was introduced right after Thomson's 1897 discovery of the electron, then called corpuscles. He said that no matter where matter came from, it contained particles that were the same and are smaller than the atoms that matter is formed from. The model was a round thick liquidy substance whose total charge canceled out the charge of the electrons.He came to this conclusion by using a cathode ray scope. This theory was proved wrong by the gold foil experiment by Rutherford. This experiment said that the atom contained a nucleus which had a highly positive charge. When this experiment came out, people drifted away from Thomson's theory on the atomic model and moved towards Rutherford's.
This video is a demonstration of how a cathode ray which Thomson used to create his atomic model.