Explain what led to the plum pudding model of the atom being replaced by the nuclear model of the atom.

An early model which was based on a scientific idea on atomic structure was the plum pudding model. In this model, it was believed the atom was a sphere of positive charge with negatively charged electrons scattered around the atom like plums in a pudding. An alpha particle scattering experiment was carried out where alpha particles were directed at gold foil. Most of the alpha particles passed straight through showing the atom was mostly empty space, a few alpha particles deflected at large angles, so the mass is concentrated at the centre of the atom. It was also concluded the nucleus must be positively charged, and therefore the plum pudding model was replaced by the nuclear model.