Model of the atom

Austin Linton

John Dalton-1803 


Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.
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1897-JJ Thomson

Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram.
Studied "canal rays" and found they were associated with the proton H + .
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Hantaro Nagaoka-1904


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
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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.
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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.

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Louis de Broglie-1924


proposed that electrons have a wave/particle duality.
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Erwin Shrodinger-1926

Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom.
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James Chadwick-1932

Used alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
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