Scientist

Dalton

Sep 6, 1766

Dalton proposed that all matter is made of atoms and that these atoms cannot be broken into smaller particles.

Thomson

Dec 18, 1856

Thompson came up with the "plum pudding model" for the atom. He was the first scientist to propose that the atom was not the smallest particle but in fact contained small negative particles called electrons. He proposed that these electrons sat in a positive jelly like plums in a plum pudding.