Rutherford's experiment was done to prove Thompson's Plum Pudding Model. In this model, the protons and electrons are both inside the nucleus. The atoms is neutral because the charges cancel out. Rutherford's hypothesis was that, when a beam of cathode rays hits the gold foil, all the light should pass through. If the Plum Pudding model was correct, that would have been the result. However, it wasn't.
