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John Dalton - Atomic Theory
Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. -
Period: to
Atomic Theory Timeline
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JJ. Thomson - Cathode Ray Tube
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 + -
Robert Andrew Millikan - Oil Drop Experiment
determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron. -
Ernest Rutherford - Gold Foil
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 - Bohr Model
Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of sucessive orbital shells of electrons. -
Erwin Rudolf Jusef Alexander Schrodinger - Schrodinger model
Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom. -
James Chadwick - The Neutron
Using alpha particles discovered a neutral atomic particle with a mass close to a proton. Thus was discovered the neutron.
