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(400 BC) First suggested the existence of atoms
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wanted to explain what was known about light's behavior assuming light consists of particles
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First to use truely quantitative research. Observations led to the law of conservation of mass
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Observeed that the composition of water is always 11% hydrogen and 89% oxygen. Proposed the law of definite proportions.
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Transformed the idea and formed Dalton's atomic theory
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published classification system
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formulated the periodic table of elements.
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Created the cathode ray tube and found that there was charged particles that flowed through the tube when electricity was passed through the tube.
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Observed cathode ray and saw some particles were going the opposite way of the cathode rays. He called those particles protons.
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studied the affect of x-rays on photographic film. He discovered some chemicals spontaneously decompose and give off very pentrating rays.
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Discovered the electron when expiramenting with a cathode ray. Created the plum pudding model
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discovered the radioactive elements polonium and radium
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Tried describing why metals start blackthen red, yellow, white as temperature increases
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Used quantum theory to explain photoelectric effect. His theory was that light behaves as a stream of particles and explains the photo electric effect
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Carried out JJ's expiraments; oil drop expirament
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Found that atom has a small dense positively charged nucleus. He did the gold foil expirament
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Proposed that an atom absorbs/emits light and that the electron is found in a specific path around the nucleus
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Using x-ray tubes he determined the charges on the nuclei of most atoms
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Asked can particles behave as matter?
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Made the quantum mechanical model. Electrons don't follow a specific path but is found in a cloud around the nucleus.
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uncertanty principle. Stated that it is impossible to know both velocity and position of a patricle at the same time
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Discovered the neutron