Key Contributions:
* Discovery of the Electron: In 1897, Thomson conducted experiments using cathode ray tubes, which demonstrated that cathode rays were composed of negatively charged particles, which he named "corpuscles." These particles were later recognized as electrons.
* Plum Pudding Model of the Atom: Thomson proposed the "plum pudding model" of the atom, which suggested that the atom was a positively charged sphere with negatively charged electrons embedded in it, like plums in a pudding.
* Positive Rays: Thomson also investigated "positive rays" (later identified as positively charged ions) which he discovered in 1898. He determined their charge-to-mass ratio and showed that they could be deflected by electric and magnetic fields.
* Isotopes: Through his studies of positive rays, Thomson realized that different elements could have atoms with the same chemical properties but different masses. He called these different forms "isotopes," which we now know are atoms of the same element with different numbers of neutrons.
Awards and Honors:
* Nobel Prize in Physics (1906)
* Knight Bachelor (1908)
* Order of Merit (1908)
* Cavendish Professor of Physics at Cambridge University (1884-1918)
Legacy:
Thomson's work revolutionized our understanding of the atom and the nature of matter. His discovery of the electron laid the foundation for modern atomic physics and quantum mechanics. He is considered one of the most influential physicists of the 20th century.