Question

Explain the shortcomings of the J. J. Thomson, Rutherford and Bohr Atomic model based on some solid physical principle. How were these shortcoming rectified?

Answer 1

ANSWER
[A](i)SHORTCOMING OF J.J. THOMSON MODEL:
J.J. Thomson's atomic model failed to explain how the positive charge holds on the electrons inside the atom. It also failed to explain an atom's stability. The theory did not mention anything about the nucleus of an atom. It was unable to explain the scattering experiment of Rutherford.

(ii)SHORTCOMINGS OF RUTHERFORD'S MODEL:
Rutherford's model was unable to explain the stability of an atom. According to Rutherford's postulate, electrons revolve at a very high speed around a nucleus of an atom in a fixed orbit.While revolving around the nucleus the electron wold ratdiate energy and become slows down and gradually falls into the nucleus.
Rutherford's theory was incomplete because it did not mention anything about the arrangement of electrons in the orbit.

(iii)SHORTCOMINGS OF BOHR ATOMIC MODEL:
The path of electron around nucleus is considered to be circular of definite radius but in reality it can be at any distance from the nucleus.
The model is based on spectra of atoms and newton's laws of motion which are not applicable to microscopic particles.

[B]Bohr improved Rutherford's model by proposing that electrons travelled about the nucleus in orbits that had specific energy levels. They could jump from one level to another but could not be at any place in between, and they would absorb or emit specific amounts of energy (quanta) when they jumped between levels.