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Aristotle claimed that all matter was either fire, water, earth, or air. The four qualities of those elements were dryness, hotness, wetness, and coldness. No one challenged these claims because of his reputation.
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Refined Parmenides's early theory of building blocks and gave it a name, atom.
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Parmenides, an ancient Greek philosopher, comes up with the idea that everything is made up of very small building blocks
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Came up with a theory of how atoms worked.
1. all elements are composed of tiny indivisible parts called atoms
2. atoms of same elemetn are the same
3. atoms make compounds
4. atoms are rearranged in chemical reactions
the first two statements were proven false, but the last two remain true. -
Mendeleev was a Russian chemist who developed an early form of the periodic table that was composed of the 65 discovered elements arranged by atomic weight. They were further arranged by certain physical traits and properties. Three elements were predicted and discovered within his lifetime because of his periodic table.
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JJ Thompson discovered and proved the existence of the electron by his Cathode ray tube experiement.
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Millikan was responsible for discovering the mass and charge of the electron.
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Developed a model of the atom that suggested a positive nucleus with negative electrons swarming around it.
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Discovered that electrons don't all just flow freely around the nucleus, they have different energy levels depending on the distance away from the center.
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Chadwick discovered the neutron, the other particle in the nucleus of the atom that accounts for the other half of the mass.
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Group of scientists doing nuclear research which resulted in the creation of the nuclear bomb.
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Shroedinger's model that more accurately depicts the pathways of an electron. He also came up with an equation that finds out where an electron was the instant before.
