The Nuclear Electron Hypothesis

Historical Surprises1

“…That, however, was in direct conflict with experiment, which had established that the nitrogen-14 nucleus actually obeys Bose-Einstein statistics -a conflict that was resolved immediately if it consisted of 7 neutrons and 7 protons for a total of 14 particles, an even number of particles. (Stuewer 1983). Thus, with Chadwick's discovery this puzzle disappeared immediately.…”

Changing Landscapes of Nuclear Physics

“…In the context of the Dirac theory this problem lead to 'Klein's paradox', which stated that the electron, due to its large Compton wavelength, should escape through the walls of the potential hole of the nucleus by being transformed into a state of negative mass (Stuewer 1983;Beiser 1981, p. Trying to attenuate this problem by introducing electrons into the nucleus, and distributing them among the protons in such a way that the resulting configuration should remain stable, eventuated in (c) the difficulty that an electron confined within the tiny dimensions of a nucleus should escape from the central core because of the high energy it ought to have according to the principle of uncertainty, an energy that was much higher than that carried by observed beta-emissions from nuclei.…”

“…In addition, no major differences between proton-proton, neutron-proton, or neutron-neutron forces could be detected (see Bethe 1936, §18) -in opposition to Majorana, who had stipulated the neutronproton force as being the sole cause for nuclear cohesion (Majorana p. 139). They were made possible by the discovery of the neutron, which, although not in a single step (Stuewer 1983), exorcized the electron from the nucleus, thereby dissolving the anomaly that a particle as light as the electron corresponds to a wave function with an amplitude much too large to be confmed within such a small space as the atomic core. Any rapidly decreasing function ( ... ), a rectangular potential hole or a more complicated function having the same characteristic behavior, will fit the experimental data equally well as long as no very accurate calculations of the binding energies expected for a given force, are available" (Bethe 1936, §9, p. 100) Nevertheless, these early attempts "constitute the first steps in the very wide chapter of nuclear physics dealing with the investigation of the nucleon-nucleon interaction and of its relations with the mesonic field" (Amaldi 1959, p. 6).…”

Nuclear Stability and Nucleon−Nucleon Interactions in Introductory and General Chemistry Textbooks

“…Indeed, Ernest Rutherford and other scientists took up this challenge shortly after discovering the nucleus with its tremendous charge density; they postulated the existence of nuclear electrons that acted to hold the “positively charged bodies” in the nucleus together . This widely held “nuclear electron hypothesis” was eventually discarded following Chadwick’s discovery of the neutron 1…”

“…Rutherford suggested that that these “inner atom” electrons were subject to novel forces . The nuclear electron hypothesis was challenged first on quantum mechanical grounds in the late 1920s and then gradually fell out of favor following Chadwick’s discovery of the neutron in 1932 .…”