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Joseph Proust
Proust observed that specific substances always contain elements in the same ratio by mass -
Antoine Lavoiser
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 -
John Dalton
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 -
J.J. Thomson
Discovered the electron, and that electrons have a negative. He believed that matter has a positive charge -
Max Planck
Max Planck found that when atoms vibrate enough, you can only measure the energy in discrete units -
Robert Millikan
Robert Millikan obtained the first accurate measurement of an electrons charge. -
Ernest Rutherford
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. -
Lord Rutherford
The third particle in an atom is predicted by Lord Rutherford -
Paul Dirac
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. -
Walter Bothe
first evidence of the third particle was found by Walter Bothe -
James Chadwick
James Chadwick repeated bothe’s work and found high energy particles with no charge and essentually the same mass as the proton. -
Werner Heisenberg
Werner Heisenberg concluded that charged particles bounce photons of light back and forth between them -
Louis de Brogile
Proposed a hypothesis that led the new way to present theory of atomic structure -
Hideki Yukawa
Suggested that exchange forces might also describe the strong force between nucleons -
Murray Gell-Mann and Yuval Ne'man
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
