Ernest Rutherford discovered radioactive elements, and proved that radioactivity includes the transformation of a chemical element into another element. He also differentiated and called the types of radiation into alpha and beta. All this work was done at McGill University in Canada. Leading to his Nobel Prize for Chemistry in 1908, he also discovered the nucleus of the atom and proposed, in 1911, a model similar to the solar system, in which the nucleus occupies the center and the electrons rotate around it in circular orbits.