PROTON OR PROUTON - RUTHERFORD AND THE DEPTHS OF THE ATOM

Rutherford envisioned the proton in 1914 when experiments on alpha-par ticle scattering led him to suggest that the hydrogen nucleus was the carrier of both positive charge and mass in the structure of all heavi er atoms. This was Supported by his discovery in 1919 that bombardment by alpha particles expelled hydrogen from nitrogen. In 1920, he propo sed the name proton for the hydrogen nucleus in this role but refraine d from using it, perhaps from what he considered a lack of direct expe rimental evidence. That constraint continued as he and Chadwick found hydrogen expelled from most other light nuclei. He abandoned it at las t when Blackett's cloud chamber showed the capture of the alpha partic le by a nitrogen nucleus at the time the proton was emitted. (C) 1997 American Association of Physics Teachers.