(Cheetham Hill, United Kingdom, 1856 - Cambridge, id., 1940) British physicist. Son of a bookseller, Joseph John Thomson studied at Owens College and later at the University of Manchester and at Trinity College, Cambridge. Graduated in mathematics in 1880, held the Chair in Cavendish, and subsequently, he was appointed director of the Cavendish laboratory at the University of Cambridge.
Joseph John Thomson
Thomson investigated the nature of cathode rays and showed that electric fields could cause deviating from these. He carried out numerous experiments on its deviation, under the combined effect of electric and magnetic fields, looking for the relationship between the load and the mass of the particles, proportionality maintained constant even when the cathode material is amended.
Joseph John Thomson
In 1897 he discovered a new particle and showed that it was approximately thousand times lighter than hydrogen. This particle would be baptised with the name of electron, designation proposed years earlier by the Irishman George Johnstone Stoney, who had theorized about his existence. Joseph John Thomson was, therefore, the first who identified subatomic particles, and arrived at important conclusions about these negatively charged particles: with the appliance that was built was the relationship between electric charge and mass of the electron.
Thomson examined also the positive rays, studied previously by Eugen Goldstein, and in 1912 discovered the mode used in the separation of atoms of different mass. The objective was achieved positive rays in electric and magnetic fields, diverting method now called mass spectrometry. With this technique he discovered that the neon has two isotopes, the neon-20 and neon-22.
All these works served to Thomson to establish a new model of the structure of the atom that was incorrect, since it meant that positively charged particles were homogeneously mixed with the negative.
Thomson's physics received the Nobel Prize in 1906 for his studies about the passage of electricity through gases inside. He calculated the amount of electricity transported by each atom and determined the number of molecules per cubic centimeter. He wrote several works, including The Discarge of Electricity Through Gases, Conduction of Electricity Through Gases, The Corpuscular Theory of Matter, The Electron in Chemistry and Recollections and Reflections. In 1937, his son George Paget Thomson was also awarded the prize Nobel Prize in Physics for the discovery of the diffraction of electrons.