Laws Of Chemical Combination And Dalton’s Atomic Theory

Laws of Chemical Combination

After much experimentations, Lavoisier and Joseph L. Proust proposed two laws of chemical combination.

1.  Law of conservation of mass:

This
the law states that during a chemical reaction the sum of masses of the
reactant and the product remains unchanged or we can say that mass can
neither be created nor destroyed. This is known as the law of
conservation of mass

2.  Law of constant proportion:  It is also known as “the law of definite proportion”

This
the law states that in a pure chemical compound elements are always
present in the definite proportion by mass irrespective of where the
the compound came from or who prepared it.

Dalton’s Atomic Theory: 

1. The two theories proposed by Lavoisier and Joseph L. Proust lacked appropriate explanations.

2. British chemist John Dalton provided the basic theory about the nature of matter, he took the idea of divisibility of matter which was till then just a philosophy.

3. He said that the smallest particles of matter are atoms and thus, he provided an explanation for ‘the law of conservation of mass’ and ‘the law of definite proportions’.

4. According to Dalton’s atomic theory, all matter, whether an element or compound or mixture is composed of small particles called atoms.

Postulates of Dalton’s atomic theory:

1.  Every matter is made up of very tiny particles called atoms.

2.  Atoms are indivisible particles, that can neither be created nor destroyed in a chemical reaction.

3.  Atoms of a given element are identical in mass and chemical properties.

4.  The atoms of different elements has different masses and chemical properties.

5.  Atoms combine in the ratio of small whole numbers to form compounds.

6.  The relative number and kinds of atoms are constant in a given compound.