what were the drawbacks of thomson model of atom
Thomson 's 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