Atomic Theory Atomic Theory is the study of atoms. Atoms are the smallest forms of matter that can still be considered/recognized as elements. Atoms are what make up everything on our earth, from molecules to monkeys. Atoms are joined together to make molecules, which are in turn joined together to make everything else. To give you an idea of the size of an atom, Encarta Online describes it as being "so small that a single drop of water could contain more than a million million billion atoms". I think they could've used more scientific terms, but you get the idea at least. In the early half of the 19th century, John Dalton (a chemist, who man