Question

What are the postulates of Dalton’s atomic theory?

Answer 1

The first atomic theory which is a complete attempt to explain all matters in terms of atoms and its theory. This theory is based upon the law of conservation of mass and the law of constant proportion.

Complete step by step answer:
The atomic theory was developed by the English chemist John Dalton in 1803 and it is based upon a few postulates which basically describe the atom and its property.
Anything that occupies space and has mass is termed as matter and all matter consists of tiny particles known as atoms. Atom is really very small, having dimensions in nanometers; it is difficult to study its characteristics as an isolated atom so Dalton’s atomic theory suggests some postulates based upon the law of conservation of mass and the law of constant proportion.
The postulates of Dalton’s atomic theory are:
-Every matter is made up of very small particles which are known as atoms.
-Atoms are indivisible particles which are neither created nor destroyed in a chemical reaction.
-Atoms belonging to the same element are identical in mass as well as in their properties.
-Atoms belonging to different elements have different masses and chemical properties.
-Atoms always combine in the ratio of small whole numbers to form compounds.
-The relative numbers and kinds of atoms are constant in a given compound.

Note: There were some drawbacks of Dalton’s atomic theory:
-The concept of indivisibility was proved wrong and it further other theory explained that atoms can be further divided into subatomic particles that are electron, neutron and proton. When isotopes were discovered, it is highlighted that atoms of the same element have different masses.
-Indivisible means that a substance cannot be further divided. It is true that atoms are the smallest particles that can take part in a chemical reaction.