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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.
The atomic nucleus shown expanded more than 10,000 times its size relative to the atom; electrons have no measurable diameter. The Rutherford model is a name for the first model of an atom with a compact nucleus. The concept arose from Ernest Rutherford discovery of the nucleus.
On April 30, John Cockcroft and Ernest Walton publish the first disintegration of an atomic nucleus, popularly described as splitting the atom. They report the production of two alpha particles from the bombardment of lithium-7 nuclei by protons, using a Cockcroft–Walton generator at the University of Cambridge 's Cavendish Laboratory . [ 7 ]
Ernest Thomas Sinton Walton (6 October 1903 – 25 June 1995) was an Irish physicist who shared the 1951 Nobel Prize in Physics with John Cockcroft "for their pioneer work on the transmutation of atomic nuclei by artificially accelerated atomic particles".
One product of the reaction was the proton; the other product was shown by Patrick Blackett, Rutherford's colleague and former student, to be oxygen: 14 N + α → 17 O + p. Rutherford therefore recognised "that the nucleus may increase rather than diminish in mass as the result of collisions in which the proton is expelled". [56]
The nucleus of an atom consists of neutrons and protons, which in turn are the manifestation of more elementary particles, called quarks, that are held in association by the nuclear strong force in certain stable combinations of hadrons, called baryons. The nuclear strong force extends far enough from each baryon so as to bind the neutrons and ...
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.
Otto Robert Frisch was born in Vienna in 1904 to a Jewish family, the son of Justinian Frisch, a painter, and Auguste Meitner Frisch, a concert pianist. [4] He himself was talented at both but also shared his maternal aunt Lise Meitner's love of physics and commenced a period of study at the University of Vienna, graduating in 1926 with some work on the effect of the newly discovered electron ...