The "plum-pudding" is disproved by the gold foil experiment by Ernest Rutherford, when he discovered the nucleus of the atom.
Marie Curie receives a second Nobel Prize, this time in Chemistry, for the isolation of radium and polonium and for her investigation of their chemical properties.
French physicist Antoine Henri Becquerel's experiments led to the discovery of radioactivity. He observed that the element uranium can blacken a photographic plate, even though separated from it by glass or black paper. He also observed that the rays that produce the darkening are capable of discharging an electroscope, indicating that the rays possess an electric charge.
Wilhelm Roentgen of Germany, while conducting experiments with cathode rays, accidentally discovers a new and different kind of ray. These rays were so mysterious that Roentgen named them "x-rays." He received the first Nobel Prize in Physics in 1901 for this discovery.