What significant change did the Geiger-Marsden experiment bring to the concept of atomic structure?

The Geiger-Marsden experiment, also known as the Rutherford gold foil experiment, fundamentally altered the understanding of atomic structure by demonstrating that atoms have a small, dense nucleus at their center. This conclusion was drawn from their observations where most alpha particles passed through the gold foil, but a small fraction were deflected at large angles. This indicated that while atoms are mostly empty space, there is a concentrated area of positive charge and mass in the nucleus, which explains the behavior of the particles. This discovery led to the planetary model of the atom, where electrons revolve around a central nucleus, marking a pivotal shift from earlier models that suggested atoms were homogeneous and solid throughout. The identification of the nucleus as a critical part of atomic structure was crucial for further developments in atomic theory.