Dalton Atomic Theory

    In the early 19th century, scientists found out that the elements are following certain laws while combining with other elements. Scientists were confused why the elements are not combining in the arbitrary proportions but only in fixed proportions.

Many scientists tried to give appropriate answers for this behavior of elements. At last an English school teacher JOHN DALTON proposed the basic theory about this nature of matter. His laws are as follows-

1.If the mass to be conserved, then all the elements must be made of very extreme tiny particles called Atoms.

2.If the law of constant proportion to be followed then the substance or matter should contain same type of particles in it throughout it.


Based on the above postulations, Dalton proposed a new system of chemical philosophy known as “Dalton Atomic Theory”.

Postulates of Dalton Atomic Theory:

1.Matter consists of indivisible particles called ATOMS.

2.Atoms are neither created nor destroyed in a chemical reaction. Chemical reaction makes reorganization or rearrangements of atoms.

3.All the atoms of given element have identical mass and will have identical properties. Atoms of different element have different mass and will have different properties.

4.Compounds are formed when atoms of different elements combined together in simple whole number ratios.

5.When atoms of different elements combine together in different whole number ratios, they form different compounds.