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Provided a more detailed and systematic view of the physical world.
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Believed materials on Earth were made of Earth, Fire, Water, and Air.
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Mass is conserved in a chemical reaction, but the oxygen and hydrogen atoms stay the same before and after.
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Published his law of definite proportions, which states that a compound is composed of exact proportions of elements by mass regardless of how it was created.
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Introduced a theory that proposed that elements differed due to the mass of their atoms.
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Discovered that a magnetic field influenced polarized light.
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Discovered the existence of radioactivity.
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Discovered the electrons in atoms.
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Deduced that radioactivity does not depend on how atoms are arranged into molecules, but rather that it originates within the atoms themselves.
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Calculated how the movement of molecules in a liquid can cause the Brownian movement.
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Helped to quantify the charge of an electron.
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Demonstrated the atom has a tiny, heavy core.
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Proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities.
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Originator of the quantum theory of energy.
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Discovered the Neutrons in atoms.