Mention briefly the salient features of Dalton's atomic theory (five points).
Salient features of Dalton's atomic theory:
1. Matter consists of very small and indivisible particles called atoms, which can neither be created nor can be destroyed.
2. The atoms of an element are alike in all respects i.e. size, mass, density, chemical properties but they differ from the atoms of other elements.
3. Atoms of an element combine in small numbers to form molecules of the element.
4. Atoms of one element combine with atoms of another element in a simple whole-number ratio to form molecules of compounds.
5. Atoms are the smallest units of matter that can take part in a chemical reaction during which only the rearrangement of atoms takes place.