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Plato introduced atomic theory
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Theory that atoms were indestructible, hard, and move through infinant numbers through space.
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Aristotles' theory was matter is made out of atoms.
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Started theory of chemical reaction to oxygen.
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Found out atoms from an element are different from atoms of another element
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All metals are made up from two principals. mercury and sulfer
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When elements are ordered from low to high mass, every 8th element is a repetition of the properties of the starting element.
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Birth of Robert millikan physicist
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Created periodic table thinking element properties are a periodic function of their atomic weight.
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Heinrich Radolf Hertz discovered when ultraviolet light shines on two metal volteges and the light changes voltege.
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After opening a drawer Henri Becquerel discovered spontanious radioactivity
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Found out by J.J. Thomson
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Light exists as tiny massless particles called photons with properties of a wave and partical
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Supposed to look like a plum made by J.J. Thomson. Represents positive dough with negative electrons stuck inside
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Robert Milikan dicovered elementary charge of electron from oil drop test
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Had a peice of gold be hit with alpha particals. The alpha particals went through and showed Ruthford gold atoms were empty space
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Explained atoms move in an orbit and not anywhere between.
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Atomic number is the number of atomic charges in the atoms nucleus
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Ernest Ruthford figured out a proton is a positively charged sub molecule
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Describes waves or probobility of waves
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Werner Heinsburg found you cant know both the speed and position of a partical with 100% accuracy
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Discovered by Sir James Chadwick by bomboarding beullyium with alpha particals