What was the purpose of the gold-foil experiment?

The purpose of the gold-foil experiment, conducted by Ernest Rutherford and his associates Hans Geiger and Ernest Marsden, was to investigate the internal structure of the atom.12

By firing a beam of positively charged alpha particles at a thin sheet of gold foil, the researchers sought to observe how these particles interacted with matter. The results—most particles passing straight through while a small fraction were deflected at large angles or bounced backward—provided critical evidence that contradicted the prevailing "plum-pudding" model.134

These observations led Rutherford to conclude that the atom is composed primarily of empty space, with its mass and positive charge concentrated in a tiny, dense nucleus. This discovery fundamentally changed the scientific understanding of atomic structure and laid the foundation for modern atomic physics.123