What is Thomson's atom?
The plum pudding model.
J.J. Thomson discovered electrons with his cathode ray experiments. Before this, it was believed that atoms were indivisible. Because atoms are neutral, J.J. Thomson's model placed negatively charged electrons throughout a sphere of positive charge. The sum of the positively charged sphere and the negatively charged electrons is zero. The sphere of positive charge represented the pudding, and the electrons represented the plums.