Thomson discovers electron
Thomson is credited with discovering electrons and isotopes. He was the first to suggest that electrons were 1000 times smaller than the actual atom itself. He discovered this through his exploration of cathode rays. His experiments suggested not only that cathode rays were over 1000 times lighter than the hydrogen atom, but also that their mass was the same whatever type of atom they came from. He concluded that atoms were divisible, and that the corpuscles were their building blocks. To explain the overall neutral charge of the atom, he proposed that the corpuscles were distributed in a positive charge; "this was the "plum pudding" model—the electrons were embedded in the positive charge like plums in a plum pudding (although in Thomson's model they were not stationary, but orbiting rapidly)."