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   He said that matter was "continuous" or always present. He said that matter was "continuous" or always present.
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   Suggested that all matter was made of tiny particles that determined the property of the matter Suggested that all matter was made of tiny particles that determined the property of the matter
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   They thought that sulfur and mercury made up all metals. They paved the way of experimenting about the atomic theory by believing in a set list of laws about the universe. They thought that sulfur and mercury made up all metals. They paved the way of experimenting about the atomic theory by believing in a set list of laws about the universe.
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   He supported atomism (the belief that matter is made up of small particles) and experimented on existing elements in an attempt to prove it. He also proved oxygen's existence. He supported atomism (the belief that matter is made up of small particles) and experimented on existing elements in an attempt to prove it. He also proved oxygen's existence.
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   He grouped the elements as simple substances, metals, non-metals, and earthly substances. He grouped the elements as simple substances, metals, non-metals, and earthly substances.
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   Said that all matter is made up of atoms; atoms of certain elements are identical; and that elements/matter cannot be destroyed. Said that all matter is made up of atoms; atoms of certain elements are identical; and that elements/matter cannot be destroyed.
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   Said that equal volumes of gas that are at the exact same temperature and pressure have the same amount of molecules despite their different properties Said that equal volumes of gas that are at the exact same temperature and pressure have the same amount of molecules despite their different properties
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   Made a periodic table with spaces for elements that had not been discovered yet Made a periodic table with spaces for elements that had not been discovered yet
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   Discovered that atoms consisted of smaller components Discovered that atoms consisted of smaller components
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   Said that rays given off by radium and polonium were caused by atoms disintegrating inside the elements Said that rays given off by radium and polonium were caused by atoms disintegrating inside the elements
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   Proved the existence of atoms Proved the existence of atoms
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   Discovered the charge of an atom and learned that electrons all had the same negative charge Discovered the charge of an atom and learned that electrons all had the same negative charge
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   Said that atoms had a positively charged core called a nucleus and that electrons with a negative charge circled the nucleus Said that atoms had a positively charged core called a nucleus and that electrons with a negative charge circled the nucleus
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   Mosely's Law: Frequencies are proportional to the squares of whole numbers that are equal to the atomic number and a constant. Mosely's Law: Frequencies are proportional to the squares of whole numbers that are equal to the atomic number and a constant.
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   Said that electrons move around the nucleus in a prescribed orbit and when electrons jump from the orbit, they cause radiation Said that electrons move around the nucleus in a prescribed orbit and when electrons jump from the orbit, they cause radiation
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   Proved the existence of the neutron, a part of the nucleus with neutral charge Proved the existence of the neutron, a part of the nucleus with neutral charge