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400
Democritus (400 B.C)
His theory states that atoms are all individually created and can’t be separated no matter what scientific procedures are applied. -
John Dalton
In 1808, he proposed that a chemical element consisted of tiny particles (atoms), all have the same chemical properties. -
J.J Thomson Discovery of the Electron
Discovery of the electron and the beginning of his investigation into its charge and mass. -
J.J Thomson's Plum Pudding Model of the Atom
Thomson created a model of the atom as a sphere of positive matter in which electrons are positioned by electrostatic forces. -
J.J Thomson discovered the natural radioactivity of potassium.
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J.J Thomson proved that Hydrogen had only one electron per atom.
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J.J Thomson awarded the Nobel Prize for Physics
Thomson was awarded the Nobel Prize for Physics for his research into the electrical conductivity of gases. -
Ernest Rutherford
In 1911, he theorized about the atom having its positive charges in a very small nucleus. -
Neils Bohr publishes his model of the atomic structure
Bohr completed and published his theory of atomic structure. The theory was inspired by Rutherford's ideas of the atom and Planck's Quantum Theory. The theory became the basis for quantum theory. -
Won the Nobel Prize in Physics for his atomic structure
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Werner Heisenberg theory of Quantum Mechanics
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Erwin Schrodinger
Schrodinger stated that rather than electrons being distributed within an electron configuration of shells and energy levels, they were arranged orbitals which were systematically distributed within Electron Clouds. -
James Chadwick discovers the neutron
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Wener Heisenberg awarded Nobel Prize for Physics
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James Chadwick
Receives the Nobel Prize for physics -
Received the first U.S. Atoms for Peace Award
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Murray Gell-Mann's Quark Idea
Gell-Mann found that all of those particles, including the neutron and proton, are composed of fundamental building blocks that he named "quarks," which contained unusual properties. -
J.J Thomson study of Canal Rays & Mass Spectroscopy
Studied "canal rays" and found they were associated with the proton H +. During his study Thomson also created a method of differentiating between various substances by their mass, which is known as mass spectroscopy.
