Ernest Rutherford, not Ernest Russell Ford, conducted an experiment in 1909 that refuted the plum pudding model of the atom. Rutherford’s famous gold foil experiment involved firing alpha particles at a thin foil of gold. According to the plum pudding model, which proposed that atoms were composed of a diffuse cloud of positive charge with negatively charged electrons embedded within it, the alpha particles should have passed through the foil with little deflection.
However, Rutherford and his students observed that while most alpha particles did pass through the foil, a small fraction were deflected at large angles, and some even bounced back. This unexpected result indicated that the atom must have a small, dense, positively charged nucleus at its center, which contained most of the atom's mass, leading to the development of the nuclear model of the atom.