Rutherford concluded that most alpha particles passed through gold foil undeflected because they travelled through:

1. The gold foil experiment fired fast-moving alpha particles at a thin metal sheet. 2. Because most of the fast-moving alpha particles passed through the gold atoms undeflected, they must have travelled through essentially empty space inside the atom. 3. Because the nucleus is very small compared to the size of an atom, very few alpha particles are deflected. 4. This nuclear model of the atom, proposed over a century ago, is still used today. _Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 2 'Atoms, Molecules, and Ions', sections 2.1-2.6_