Question

Why the Plum-Pudding Model Failed

Answer 1

Dear Student,

Plum pudding model:
J.J Thomson proposed that an atom consists of a uniform sphere in which positive charge is uniformly distributed. The electrons are embeded into it in such a way as to give the most stable electrostatic arrangement. An important feature of this model is that the mass of the atom is considered to be evenly spread over the atom.

Drawbacks of above model:
a) Later it was found that the atom has concentrated mass and the positively charged nucleus is at the centre while the negatively charged electrons move in the shells around the nucleus.
b) According to this model, hydrogen can give rise to only one spectral line, contrary to the observed fact of several lines.
c) This model could not explain the large angle scattering of alpha particles by thin metal foils.

Regards