Question 1 Name the scientist who gave atomic theory of matter?
Question 2 State the various postulates of Dalton’s Atomic theory of matter?
Question 3 Give drawbacks of Dalton’s Atomic theory of matter?
Dalton’s Atomic Theory
Dalton put forward his atomic theory of matter in 1808.
Postulates
(1) All the matter is made up of very small particles called atoms.
(2) Atoms can neither be created nor be destroyed.
(3) All the atoms of a given element are identical in every respect, having same physical and chemical properties.
(4) Atoms of different elements differ in every respect i.e. mass, size and chemical properties.
(5) During chemical combination, atoms of different elements combine in small whole numbers to form compounds.
Drawbacks
(1) Dalton said that atoms are indivisible but they can be further divided into electron, proton and neutron.
(2) Dalton said that atoms of a given element have exactly same masses. It is however now known that atoms of same element can have different masses (isotopes).
(3) Dalton said that atom of different elements have different masses. It is however now known that atoms of different elements can have same masses (isobars).