Answer
When Rutherford shot alpha particles at a thin gold foil, some of the alpha particles were deflected at large angles. This shows that the alpha particles were being deflected as a result of a collision with something inside of the atom. This result led Rutherford to propose a nuclear model of an atom as opposed to Thomson's plum pudding model of an atom.
Work Step by Step
When Rutherford shot alpha particles at a thin gold foil, most of the particles went through the foil undeflected. This shows that most of an atom consists of empty space. This fact contradicts Thomson's plum pudding model of an atom which suggested that material was spread evenly throughout an atom.
Some of the alpha particles were deflected at large angles. This shows that the alpha particles were being deflected as a result of a collision with something inside of the atom. This result led Rutherford to propose a nuclear model of an atom.
