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He proposes the four element theory; earth, air, fire, and water 330 B.C
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He makes the term â€~elementsâ 360 B.C
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They proposed the idea of the atom, and invisible particle that all matter is made of. 440 B.C
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He published "The Sceptical Chymist" which was a treatise on the distinction between chemistry and alchemy. It also contained some of the earliest ideas of atoms, molecules, and chemical reaction marketing the beginning of the history of of modern chemistry
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Arranged the known elements in order of atomic weights and observed some similarities between some elements
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Develops an early version of the periodic table, with 28 elements organized by valance
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He produced a table based on atomic weights but arranged "periodically" with elements with similar properties under each other. His periodic table included the 66 known elements organized by atomic weights
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Developed a table of atomic weights & introduced letters to symbolize element
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He developed groups of 3 elements with similar properties