jan 1, 1911 - Ernest Rutherford
Ernest Rutherford sought to prove that the atom was just as JJ Thompson had described it, as a "plum pudding". He set up gold foil around a detector, put a source of radiation to shoot alpha particles at the foil. In theory, if Thompson was right, the particles would go through the gold foil, yet this was not the case as some particles strayed, some particles almost shot in the opposite direction, but most of the particles went straight through. This proved that the "plum pudding" had more than just electrons, it had a center, which was the first discovery of the nucleus.
Added to timeline:
The History of the Atom
History of the Atom