Joseph John Thomson (December 18, 1856 - August 30, 1940) was an English physicist. He is credited with discovering electrons and isotopes, and inventing the mass spectrometer. In 1905 Thomson discovered the natural radioactivity of potassium. In 1906 Tho

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Joseph John Thomson (December 18, 1856 - August 30, 1940) was an English physicist. He is credited with discovering electrons and isotopes, and inventing the mass spectrometer. In 1905 Thomson discovered the natural radioactivity of potassium. In 1906 Tho
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Image ID: G15MND
Joseph John Thomson (December 18, 1856 - August 30, 1940) was an English physicist. He is credited with discovering electrons and isotopes, and inventing the mass spectrometer. In 1905 Thomson discovered the natural radioactivity of potassium. In 1906 Thomson demonstrated that hydrogen had only a single electron per atom. Previous theories allowed various numbers of electrons. He was awarded the 1906 Nobel Prize in Physics for the discovery of the electron and for his work on the conduction of electricity in gases. He was knighted in 1908 and appointed to the Order of Merit in 1912. In 1918 he became Master of Trinity College, Cambridge, where he remained until his death. He died in 1940 and was buried in Westminster Abbey, close to Sir Isaac Newton.