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Abdera, Greece
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What they contributed:
Promulgated the atomic theory, which asserted that the universe is composed of two elements: the atoms and the void in which they exist and move
Democritus did not originate the atomic theory; he learned it from its founder, Leucippus, the author of the Big Cosmology.
What experiments:
Separated a seashell into its smallest components -
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Paris, France
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Eaglesfield, England
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What they contributed:
Defined law of conservation of mass
This helped shape atomic theory b/c matter is composed of atoms that aren’t created or destroyed during chemical reactions
What experiments:
Heat and combustion of substances, reacted oxygen with inflammable air -
Paris, France
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What they contributed:
All matter is made up of indivisible and indestructible atoms w distinct properties
What experiments:
Combined oxygen with two volumes of nitric oxide over water -
Manchester, UK
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Cheetham Hill, UK
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Kiel, Germany
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Warsaw, Poland
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Morrison, Illinois, U.S.
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Nelson, New Zealand
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Uhm, Germany
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Copenhagen, Denmark
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Vienna, Austria
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Manchester, UK
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Dieppe, France
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What they contributed:
All atoms contain negatively charged subatomic particles or electrons
Plum pudding model
What experiments:
Cathode rays were negatively charged -
What they contributed:
Quantum theory
What experiments:
Studied the diffusion of hydrogen through heated platinum -
Wurzburg, Germany
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What they contributed:
Discovered polonium and radium
What experiments:
Studied mineral pitchblende -
What they contributed:
Accurate determination of the charge carried by an electron
What experiments:
Falling-drop method -
What they contributed:
Helped revolutionize the sciences with statistics and probability
What experiments:
Mathematically proved the existence of atoms -
What they contributed:
Mass of the atom is concentrated in its nucleus
What experiments:
Gold foil experiment -
What they contributed:
Proposed a theory for hydrogen atom based on quantum theory
What experiments:
Bohr model -
What they contributed:
Particles, such as electrons, could be described not only as particles but also as waves
What experiments:
Streams of electrons were reflected against crystals -
What they contributed:
Discovered the uncertainty principle
What experiments:
Formulated quantum mechanics in terms of matrices -
What they contributed:
Wave equation that calculates the energy level of electrons in atoms
What experiments:
Bohr’s orbit theory -
What they contributed:
Proved the existence of neutrons
What experiments:
Measured mass and performed an experiment that others were tinkering with -
France
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Cambridge, UK
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Cambridge, UK
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Göttingen, Germany
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Pasadena, California, U.S.
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Princeton, New Jersey, U.S.
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Vienna, Austria
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Copenhagen, Denmark
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Cambridge, UK
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Munich, Germany
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Paris, France