A scientist named Rutherford designed an experiment to test the plum pudding model.
the components of the atom had been discovered. The atom consisted of particles called protons and electrons. However, it was not clear how these protons and electrons were arranged within the atom. J.J. Thomson suggested the"plum" model. In the model the electrons and protons are uniformly mixed throughout the atom.
Rutherford tested Thomson's hypothesis by devising his "gold foil" experiment. Rutherford reasoned that if Thomson's model was correct then the mass of the atom was spread out throughout the atom.
if he shot high velocity helium nuclei at an atom then there would be very little to deflect the helium nuclei. He decided to test this with a thin film of gold atoms.
The difference was that Rutherford shot electrons at a thin gold foil and some electrons actually came backwards. He suggested that the atom was largely empty space (because few electrons deviated) with a small, dense, positively charged nucleus.