Radioactivity discovered in 1896.

Three different types of radiation were identified by 1900.

Rutherford discovered the nucleus, through experimenting with radioactivity.

The discovery of nuclear fission in 1939, paved the way for the atom bomb and for nuclear power stations.

Nuclear accidents in 1979 and 1986 gave rise to concerns.

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.