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400 BCE
Democritus
Democritus believed that all things on earth were made of atomic atoms -
330 BCE
Aristotle
Aristotle believed that all things were made of the four elements fire, water, wind, and earth instead of the belief in atoms -
1492
Columbus arrives in America
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Robert Boyle
Creator of Boyles law. Boyles law describes inversely proportional relationships -
American revolution
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James Dalton
James daltons atomic theory stated that all elements were made of extremely small particles called atoms -
Dmitri Mendeleev
Created the first periodic table -
American civil war
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J. J. Thomson
Thomson is credited with discovering the subatomic particle -
Niels Bohr
In 1913 Niels Bohr proposed a theory of the working of a hydrogen atom -
World war 1
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Hans Geiger
Inventor of the Geiger counter that led to the discovery of the atomic nucleus -
Robert Milikan
Awarded a noble for measuring the electric charge and his work with the photoelectric effect -
James Chadwick
Discovery of the neutron -
World war 2
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The bomb dropping in Hiroshima
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Present Day