Who determined the mass-to-charge ratio of an electron?

J.J. Thompson discovered that cathode rays were made up of electrons, and determined the mass-to-charge ratio of the electrons. He found that the mass-to-charge ratio of the cathode rays was much smaller than that of hydrogen, and concluded that constituent particles (electrons) must be the building blocks of atoms. He modeled the neutral atom as a sphere of negatively charged electrons distributed amongst positively charged protons. This is known as the "plum pudding" model or the Thompson model of the electron.


Ernest Rutherford proved that the Thompson model was incorrect when he discovered that gold atoms consist of an outside layer of electrons, with a center nucleus densely packed with protons.