John Dalton

Although he also conducted research into colour blindness and gas laws, John Dalton's most significant work came in the field of atomic theory. Dalton developed the first evidence-based theory to suggest the existence of atoms, and later expanded on his work by publishing "A new system of chemical philosophy". This paper stated that atoms of different elements can be distinguished according to their atomic weight. Dalton was the first chemist to describe atoms in terms of their weight, and also the first to suggest that they cannot be created or destroyed. Although Dalton's work was hotly contested by some in his day, experiments in subsequent years have proved Dalton to be right and have cemented his place in chemistry's hall of fame