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Proust observed that specific substances always contain elements in the same ratio by mass
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Discovered conservation of mass, he proposed that in ordinary chemical reactions, matter can be can be changed in many ways but matter can not be created or destoried
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Trying to explain the findings of lavoiser and Proust, Dalton formed the basics of the basics of our present atomic theory. He stated that all matter is composed of very small particles called atoms, and that these atoms cannot be broken into smaller particles
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Discovered the electron, and that electrons have a negative. He believed that matter has a positive charge
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Max Planck found that when atoms vibrate enough, you can only measure the energy in discrete units
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Robert Millikan obtained the first accurate measurement of an electrons charge.
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Ernest Rutherford believed that he could find out about the inside of the atom using alpha rays. He used Radum as the source of the alpha rays and shinned them onto thing gold foil to see the alpha particles impact. he thought that the negatively charged electrons orbited a center like the solor system.
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The third particle in an atom is predicted by Lord Rutherford
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Produced equations which predicted an unthinkable thing at the time- a positive charged electron. He did not accept his own theory at the time. In 1932 in experiments with cosmic rays, Carl Anderson discovered the anti-electron, which proved Dirac's equations. Physicists call it the positron.
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first evidence of the third particle was found by Walter Bothe
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James Chadwick repeated bothe’s work and found high energy particles with no charge and essentually the same mass as the proton.
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Werner Heisenberg concluded that charged particles bounce photons of light back and forth between them
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Proposed a hypothesis that led the new way to present theory of atomic structure
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Suggested that exchange forces might also describe the strong force between nucleons
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Murray Gell-Mann and Yuval Ne'man independently proposed a method for classifying all the particles then known. The method became known as the Eightfold Way
