write the main reason for downfall of thomsons model of an atom ?

Geiger and Marsden carried out an experiment in which the alpha rays were collided against a thin metal foil. Their results showed that almost all incident alpha particles penetrate the foil and go straight in forward direction but a few are scattered in very large angles.
The results of the alpha particle scattering cannot be explained by Thomson's atomic model. Thomson's raisin bread model (plum pudding model) therefore cannot be valid as an atomic model.