These Scientists Fired alpha particles at a piece of Gold foil. Some of the particles passed straight through but occasionally they were bounced back, indicating that they had encountered a sizeable obstruction with a large positive charge. The plum pudding model of the atom had dictated for years that the central core of an atom was a dispersed positive charge with electrons embedded in it, not the concentrated positive field experienced by the alpha particles in Rutherford's experiment. This led to the conclusion that the nucleus  an atom existed of a central positive charge with electrons going around it.