DALTON’S ATOMIC THEORY



John Dalton, in 1803, proposed the Atomic Theory of Matter on the basis of law of chemical combination and other related chemical observation. He stated that:



–    All matter is made of atoms which are indivisible and indestructible ultimate particles.



–    All the atoms of a given element are identical, both in mass and chemical properties.



–    However, atoms of different elements have different masses and different chemical numbers.



–    Compounds are formed by the combination of different atoms in the ratio of small whole numbers.



–    Chemical reactions involve only combination, separation or rearrangement of atoms.



–    Atoms are neither created nor destroyed in the course of an ordinary chemical reaction.



Even today, the scientific community accepts the hypothesis of John Dalton with two modifications: (i) an atom is divisible and destructible, and (ii) all atoms of an element are not identical in mass. However, these aspects have not affected the basic philosophy of Dalton.