Question

what are the merits of J.J.Thomson's atomic model?

Answer 1

With this model he tried to explain the observed spectra of elements. According to him, the vibrations of electrons would give rise to electromagnetic energy radiated. He could explain with some success the process like chemical reaction, radioactivity etc.

This model had many drawbacks. The chief among them are:

(i) Since the weight of an electron is about a thousandth part of a hydrogen atom, it would mean that a single atom, especially of the heavier elements, would contain many thousand electrons. But J.J. Thomson himself found that the number of electrons in an atom cannot be greatly different from the atomic weight.

(ii) According to this model, hydrogen can give rise to only one spectral line, contrary to the observed fact of several lines.

(iii) This model could not explain the large angle scattering of alpha particles by thin metal foils

Answer 2

The following are the limitations of the $\small\bf\red{J.J.\:Thomson’s\:model}$ of an atom:-

• The model failed to explain the outcome of alpha particle scattering which was conducted by Rutherford. The model failed to depict why majority of these alpha particles pass through gold foil while some are diverted through small and big angles, while some others rebound completely, returning back on their path.
• It did not provide any experimental evidence and was established on imagination.