Final answer:
Ernest Rutherford's contribution to the understanding of the atom represented a change from prior understandings by discovering the existence of a small, dense nucleus at the center of the atom through his gold foil experiment.
Step-by-step explanation:
Ernest Rutherford's contribution to the understanding of the atom represented a change from prior understandings in a few ways. Prior to Rutherford's experiments, the prevailing belief was that the atom was a solid, indivisible particle. However, Rutherford's gold foil experiment showed that the atom is mostly empty space with a small, dense nucleus at the center. This discovery shattered the previous concept of the atom and led to the development of the nuclear model of the atom.
Example:
In the gold foil experiment, Rutherford bombarded a thin sheet of gold foil with alpha particles. He expected the alpha particles to pass straight through or be slightly deflected. However, some of the particles bounced back, which indicated the presence of a dense, positively charged nucleus at the center of the atom.
\