The plum pudding model was the idea of a positively charged sphere, with negative electrons dotted within it as the model of an atom. easiest understood drawn outA scientist named Rutherford did an experiment firiring positively charged alpha particles to a very thin sheet of gold, as close to 1 atom thin as possible. The experiment found that most alpha particles went straight through the gold without anything happening to them, only a small amount were deflected at big angles and an even smaller amount were backscattered. again, best being drawn out. The conclusions from this were that a very very small part of the atom must be positive, and that part must be concentrated in the centre due to the large angles. Also, most of the atom must have been empty space, as most of the alpha particles weren't affected. The plum pudding model was far from this, and so the new current nuclear model was formed from the results of this experiment. draw out nuclear model So in summary:plum pudding model was a positive sphere with small negative electrons, and mass and charge spread equally throughoutthe Rutherford experiment found most alpha particles passed straight through thin gold foil, some at large angles and some were backscattered this meant most of the atom must be empty space, with a small concentrated positive central nucleus hence the nuclear model was created