J.J. Thomson, or Joseph John Thomson, was a British physicist born on December 18, 1856, and he passed away on August 30, 1940. He is best known for his discovery of the electron in 1897, a groundbreaking achievement that significantly advanced the field of atomic physics. Thomson conducted experiments using cathode rays and demonstrated that they were composed of smaller negatively charged particles, which he later named electrons.
In addition to his work on the electron, Thomson also developed the "plum pudding" model of the atom, where he proposed that atoms were composed of a positively charged "soup" with negatively charged electrons embedded within it, resembling a plum pudding. This model was later superseded by the Rutherford model of the atom.
Thomson received the Nobel Prize in Physics in 1906 for his work on the conduction of electricity in gases. He also contributed to the study of isotopes and played a role in the development of the field of mass spectrometry. Throughout his career, he held various academic positions, including serving as the Cavendish Professor of Physics at the University of Cambridge.