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All matter is composed of atoms
Atoms cannot be made or destroyed
All atoms of the same element are identical
Different elements have different types of atoms
Chemical reactions occur when atoms are rearranged
Compounds are formed from atoms of the constituent elements. -
Thomson publishes his discovery of a sub atomic particle common to all matter. When investigating cathode rays using a highly evacuated discharge tube he was able to use the calculated velocity and deflection of the beam to calculate the ratio of electric charge to mass of the cathode ray.
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Proposed the quantum of light in which he states that light
behaves like a particle but also has a wave nature, giving it
a dual nature. Stated the equivalence of energy and mass
through the theory of special relativity. -
Rutherford publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space.
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Bohr applies quantum theory to Rutherford's atomic structure by assuming that electrons travel in stationary orbits defined by their angular momentum. This led to the calculation of possible energy levels for these orbits and the postulation that the emission of light occurs when an electron moves into a lower energy orbit.
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The Electron Cloud Model consisted of a dense nucleus surrounded by a cloud of electrons at various levels in orbitals.
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Found that when Uranium is bombarded by neutrons it produces smaller nuclei roughly half the size of the original Uranium nucleus.
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A type of bomb in which the energy is provided by nuclear fission. Uranium-235 and plutonium-239 are the isotopes most commonly used in atomic bombs.
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The determination of the age of an organic object from the relative proportions of the carbon isotopes carbon-12 and carbon-14 in it.
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Succeeded in making man-made elements.
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Suggested the idea of quarks called up, down, or strange,
composed of mesons and baryons, with spin 0.5 and
electric charges of 2/3, -1/3, and -1/3 respectively.
