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He made the first atomic hypothesis. His theory was that everything is made of "atoms". -
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Thought that all elements on Earth were not made of atoms except for Earth, Fire, Water and Air, themselves. -
Said that all metals were formed from two principles — mercury and sulfur. -
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He believed everything was composed of tiny particles. Stated that the volume of a gas decreases with pressure. -
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Said that all matter is composed of atoms. -
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Created the periodic table. -
Discovered the electron, and did experiments regarding atomic theory. -
Discovered that all atoms contain negatively charged subatomic particles (electrons). -
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Determined the magnitude of electron charge. -
Showed electrons having a discrete, quantifiable charge. -
Put forth the idea of a tiny, dense, positively charged core called a "nucleus". -
Discovered most of the atom is empty space around the nucleus. -
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Stated nucleus has all the positive charge and mass of an atom. -
Developed Bohr model and hydrogen atom theory. -
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Discovered the neutron. -
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