Question

Limitations of Dalton's Atomic Theory

(Min 4 points)

Answer 1

Dalton's atomic theory was the first milestone towards the inner structure of matter. It gave a powerful initiative to the scientists about the study of matter during 19th century. It held the ground for about a century. But the brilliant researches conducted in the beginning of 20th century by Sir J.J Thomson, Lord Rutherford, Neils Bohr and others have revolutionised our knowledge about the structure of atom. The main drawbacks of Dalton's Atomic Theory are:


(i) It could explain the laws of chemical combination by mass but failed to explain the law of gaseous volumes.

(ii) It could not explain why atoms of different elements have different masses, sizes, valencies, etc.

(iii) Why do atoms of the same or different elements combine at all to form molecules

(iv) What is the nature of binding force b/w atoms and molecules which accounts the existence of matter in three states, i.e., solids, liquids, and gases ?

(v) It makes no distinction b/w the ultimate particles of an element or a compound

Answer 2

Some important limitations of the theory are listed :-


◆ Atoms have been found to be made of sub-atomic particles. The important out of these are electrons, protons and neutrons.


◆ Atoms of the same element may have different masses ( Isotopes )


◆ Atoms of different elements may have same mass ( Isobars )


◆ Atoms of different elements may not always combine in simple whole number ratios to form molecules of a compound.