Question

State Dalton’s atomic theory.

Answer 1

Hint: We can say that Dalton’s atomic theory as the scientific theory on the nature of matter. It was put forward by physicist and chemist John Dalton in 1808. The main statement of the theory was all the matter was made up of small, indivisible particles known as atoms.

Complete Step by step answer:
Earlier time matter was one of the most important subjects of research for the science enthusiast. Everyone wanted to find the fundamental particles that make matter. This led to many postulates and theories regarding the matter.

Among one of those postulates were by John Dalton in 1808. Let us see the postulates of John Dalton.
- We can say that all matter present is made up of tiny, indivisible particles called an atom.
- All atoms in a specific element have same properties such as its mass, size etc. however atoms of different elements show different properties and they vary in mass and size
- Atoms can neither be created nor be destroyed; they cannot be divided into smaller particles.
- Compounds can be formed by combining different elements in fixed whole number ratios.
- Atoms can be combined, rearranged or separated in a chemical reaction.

Limitation of Dalton’s atomic theory:
- It cannot be applied to subatomic particles, as discovery of subatomic particle disapproved the postulate
- Isotopes: Discovery of isotopes found that all atoms do not have identical masses or density.
- Element does not have to combine in a whole number of ratios to form compounds. Example: sugar.
- Dalton’s theory does not account for allotropes.

Note: It should be noted that Bohr’s model encapsulates the current understanding of atoms. We can say electron cloud model is currently most accepted model of atom as it retains the concept of nucleus from Bohr and Rutherford’s model of atom