Which experiment did Rutherford conduct to demonstrate that atoms are mostly empty space?

The Gold Foil Experiment, conducted by Ernest Rutherford, is the pivotal experiment that demonstrated atoms are mostly empty space. In this experiment, Rutherford directed a beam of alpha particles at a very thin sheet of gold foil. He expected the particles to pass through with little deflection, based on the prevailing plum pudding model of atomic structure, which suggested that positive charge was spread out evenly throughout the atom.

However, what Rutherford observed was unexpected: while most alpha particles passed through the foil, a small fraction were deflected at large angles, with some even bouncing back towards the source. This led him to conclude that the majority of the atom is empty space, allowing alpha particles to pass through, while the presence of a dense, positively charged nucleus caused the large deflections. Rutherford's findings fundamentally changed the understanding of atomic structure, leading to the modern view of the atom that includes a small, dense nucleus surrounded by a vast amount of empty space.