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  2. J. J. Thomson - Wikipedia

    en.wikipedia.org/wiki/J._J._Thomson

    Plaque commemorating J. J. Thomson's discovery of the electron outside the old Cavendish Laboratory in Cambridge Autochrome portrait by Georges Chevalier, 1923 Thomson c. 1920–1925 Thomson was elected a Fellow of the Royal Society (FRS) [ 25 ] [ 50 ] and appointed to the Cavendish Professorship of Experimental Physics at the Cavendish ...

  3. History of mass spectrometry - Wikipedia

    en.wikipedia.org/wiki/History_of_mass_spectrometry

    In the bottom right corner of this photographic plate are markings for the two isotopes of neon: neon-20 and neon-22. In 1913, as part of his exploration into the composition of canal rays, J. J. Thomson channeled a stream of ionized neon through a magnetic and an electric field and measured its deflection by placing a photographic plate in its ...

  4. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    The term isotope was coined by Margaret Todd as a suitable name for these varieties. [66] That same year, J. J. Thomson conducted an experiment in which he channeled a stream of neon ions through magnetic and electric fields, striking a photographic plate at the other end. He observed two glowing patches on the plate, which suggested two ...

  5. Mass spectrometry - Wikipedia

    en.wikipedia.org/wiki/Mass_spectrometry

    Discovery of Neon Isotopes In a typical MS procedure, a sample, which may be solid, liquid, or gaseous, is ionized , for example by bombarding it with a beam of electrons . This may cause some of the sample's molecules to break up into positively charged fragments or simply become positively charged without fragmenting.

  6. Discovery of the neutron - Wikipedia

    en.wikipedia.org/wiki/Discovery_of_the_neutron

    A schematic of the nucleus of an atom indicating β − radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, a red sphere was a proton with positive charge, and a blue sphere was a proton tightly bound to an electron, with no net charge.

  7. Timeline of particle discoveries - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_particle...

    Discovery of the ultraviolet radiation below 200 nm, named vacuum ultraviolet (later identified as photons) because it is strongly absorbed by air, by the German physicist Victor Schumann [2] 1895 X-ray produced by Wilhelm Röntgen (later identified as photons) [3] 1897 Electron discovered by J. J. Thomson [4] 1899

  8. Plum pudding model - Wikipedia

    en.wikipedia.org/wiki/Plum_pudding_model

    An atom with seven electrons arranged in a pentagonal dipyramid, as imagined by Thomson in 1905. The plum pudding model is an obsolete scientific model of the atom.It was first proposed by J. J. Thomson in 1904 following his discovery of the electron in 1897, and was rendered obsolete by Ernest Rutherford's discovery of the atomic nucleus in 1911.

  9. History of chemistry - Wikipedia

    en.wikipedia.org/wiki/History_of_chemistry

    He is remembered for proving the existence of isotopes of certain radioactive elements, and is also credited, along with others, with the discovery of the element protactinium in 1917. In 1913, J. J. Thomson expanded on the work of Wien by showing that charged subatomic particles can be separated by their mass-to-charge ratio, a technique known ...