© William P. Reinhardt, 2010.
Following his discovery of the electron as a negatively charged particle with a very small mass compared to the mass of the atom itself, J.J. Thomson introduced his quintessentially British plum pudding model of the atom. Taking relative mass as suggestive of relative size, Thomson imagined an atomic model with a large and massive positively charged entity, with tiny, far less massive electrons embedded therein. Shown here are actual raisins in a scone from a Seattle bakery, but the idea is the same. (Unit: 6)