The atomic theory, as proposed by John Dalton, is composed of five parts.
1) Elements are composed of extremely small particles known as atoms.
2) Atoms of a given element are identical in size, mass, and other properties; atoms of different elements are different
3) Atoms cannot be subdivided, created, or destroyed.
4) Atoms of different compounds combine in simple, whole-number ratios to form chemical compounds.
5) In chemical reactions, atoms are combined, separated, or rearranged.