Model of the atom
Hantaro Nagaoka developed the earliest published quasi-planetary model of the atom. This graduate of the University of Tokyo from 1887 spent his postdoctoral period in Vienna, Berlin and Munich before obtaining a professorship in Tokyo to become Japan's foremost modern physicist
Ernest Rutherford -1911
Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil. He established that the nucleus was: very dense,very small and positively charged. He also assumed that the electrons were located outside the nucleus.
Niels Bohr -1913
In 1913 one of Rutherford's students, Niels Bohr, proposed a model for the hydrogen atom that was consistent with Rutherford's model and yet also explained the spectrum of the hydrogen atom. The Boher Model was based on the following assumptions.
Louis de Broglie-1924
proposed that electrons have a wave/particle duality.
Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom.
Used alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.