| 1985 | Roentgen | Roentgen discovered x-rays |
| 1896 | Becquerel | Discovered radioactivity |
| 1897 | Rutherford | Discovered alpha and beta rays |
| 1898 | Curies | Discovered Polonium and Radium |
| 1900 | Becquerel | Showed beta rays identical to cathode rays |
| 1900 | Villard | Discovered gamma rays |
| 1900 | Dorn | Radon gas discovered to be radioactive |
| 1903 | Rutherford | Radioactivity .....transmutation of elements |
| 1909 | Rutherford | Identified alpha rays as helium ions |
| 1911 | Rutherford | Scattering experiment .....nuclear model |
| 1912 | Thomson | Discovered the existence of isotopes |
| 1913 | Geiger | Invented the Geiger counter |
| 1919 | Rutherford | Achieved first transmutation of elements |
| 1932 | Chadwick | Discovered the neutron |
| 1934 | Joliot-Curie | Produced the first artificially radioactive substance. |
| 1938 | Hahn & Strassman | Achieved nuclear fission |
| 1942 | Fermi | Developed the first nuclear reactor |
| 1979 | Three Mile Island accident in Pennsylvania. | |
| 1986 | Chernobyl accident occurred in the Ukraine. |