1895
Wilhelm Roentgen of Germany, while conducting experiments with cathode rays, accidentally discovers of 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.
1896
French physicist Antoine Henri Becquerel's experiments led to the discovery of radioactivity. He observed that the element uranium can blacken a photographic plate, although 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.
1897
J. J. Thomson of Britain discovers the electron, while also studing cathode rays. He received the Nobel Prize in Physics in 1906 for this discovery.
1899
Ernest Rutherford discovers two kinds of rays emitting from radium. The first he calls alpha rays; the more penetrating rays he calls beta rays.