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John Dalton theory was based on the idea that each element has its own individual atom. He also made the inference that atoms are alike but they differ. He also assigned atomic weights to the 20 known elements at the time -
JJ Thomson discovered the electron. He discovered this by experimenting with a Crookes, or cathode ray. He determined that the cathode rays were negatively charged. He also studied positively charged particles in neon gas. -
Ernest Rutherford discovered alpha and beta rays, and that made the laws of radioactive decay. He also identified the alpha particel as a helium nuclei. He did this by using the fold foil experiment. -
He discovered there are shells on the outer of the nucleus, he measured liquid surface tension using oscillating fluid jets -
He discovered neutrons by bombarding Beryllium with Alpha particles from the natural radioactive decay of Polonium