In 1803 English chemist Dalton put forward his atomic theory.
The main postulates of the theory are as follows.
1. Elements are made up of very small indivisible particles called atoms.
2. All atoms of a particular element are identical in shape, mass and other properties, but are different from the atom of other elements.
3. Atom of one element can not be converted into that of another element.
4. Atoms of an element combine in integral ratio with those of other elements to form a compound
5. An atom can neither be created nor destroyed.
