He proposed his atomic theory in the early 1800s, which included the following postulates:
* Matter is composed of tiny, indivisible particles called atoms.
* Atoms of a given element are identical in size, mass, and chemical properties.
* Atoms of different elements have different properties.
* Chemical reactions involve the combination, separation, or rearrangement of atoms.
While Dalton's model was a significant step forward in understanding matter, it was later revised and expanded as scientists discovered more about the structure of the atom. We now know that atoms are not simply solid balls, but have a complex internal structure with a nucleus containing protons and neutrons, and electrons orbiting the nucleus.
