HISTORY

Around 1805, John Dalton proposed some basic assumptions about atoms. Some of these ideas dated back to the ancient Greeks. They were:

1. All mater is made up of very small, discrete particles called atoms.

2. All atoms of an element are alike in weight and different from the weight of any other kind of atom.

3. Atoms unite in chemical changes to form compounds

4. The atom is not entirely altered in the formation of a compound, and its weight remains constant.