Final answer:
Rutherford's Gold Foil Experiment disproved the plum pudding model by showing that alpha particles were sometimes deflected by a dense nucleus within the atom, leading to the planetary model of the atom.
Step-by-step explanation:
In 1911, Ernest Rutherford, along with his coworkers Hans Geiger and Ernest Marsden, performed what is now known as the Gold Foil Experiment. This experiment was pivotal in the development of the nuclear model of the atom, disproving the previously accepted plum pudding model proposed by J.J. Thomson. Rutherford and his team bombarded thin sheets of gold foil with fast moving alpha particles, expecting them to pass through with minimal deflection as Thomson's model suggested.
However, while most alpha particles went straight through the gold foil, they found that roughly 1 in 20,000 were deflected at larger angles, and some even bounced back toward the source. This observation indicated that there was a small, dense, positively charged nucleus at the center of the atom. Such deflection could not occur if the positive charge were spread out throughout the atom, as in the plum pudding model.
Rutherford's planetary model of the atom was devised to explain these observations. It postulated that atoms consist of a dense nucleus surrounded by orbiting electrons, much like planets orbiting the sun. This model laid the foundation for modern atomic theory and influenced further research, including the early quantum theory for the hydrogen atom and Bohr's quantum model, which explained the radiation spectrum of atomic hydrogen.