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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. History of chemistry - Wikipedia

    en.wikipedia.org/wiki/History_of_chemistry

    In 1897, J. J. Thomson discovered the electron using the cathode-ray tube. In 1898, Wilhelm Wien demonstrated that canal rays (streams of positive ions) can be deflected by magnetic fields and that the amount of deflection is proportional to the mass-to-charge ratio. This discovery would lead to the analytical technique known as mass ...

  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. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Back in 1815, William Prout observed that the atomic weights of many elements were multiples of hydrogen's atomic weight, which is in fact true for all of them if one takes isotopes into account. In 1898, J. J. Thomson found that the positive charge of a hydrogen ion is equal to the negative charge of an electron, and these were then the ...

  8. Thomson problem - Wikipedia

    en.wikipedia.org/wiki/Thomson_problem

    The Thomson problem is a natural consequence of J. J. Thomson's plum pudding model in the absence of its uniform positive background charge. [ 12 ] "No fact discovered about the atom can be trivial, nor fail to accelerate the progress of physical science, for the greater part of natural philosophy is the outcome of the structure and mechanism ...

  9. Rutherford scattering experiments - Wikipedia

    en.wikipedia.org/wiki/Rutherford_scattering...

    The prevailing model of atomic structure before Rutherford's experiments was devised by J. J. Thomson. [2]: 123 Thomson had discovered the electron through his work on cathode rays [3] and proposed that they existed within atoms, and an electric current is electrons hopping from one atom to an adjacent one in a series. There logically had to be ...