history of chemistry

(BC) Aristotle states the four elements-earth, wind, fire, water

300

http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.html

(BC) Democritus states atoms to be the simplest form of matter and all matter was made of them

430

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John Dalton states atomic theory-all matter is made of small invisible atoms

Jan 1, 1802

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Eugene Goldstein discoveres the proton

Jan 1, 1855

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thomson discovers the electron and states that the electron is the only part of an atom

Jan 1, 1897

http://www.aip.org/history/electron/jjhome.htm

Rutherford found the the first half-life of an element, thought the atom was syrrounded by nearly weightless electrons

Jan 1, 1908

http://www.pbs.org/wgbh/aso/databank/entries/bpbohr.html -http://galileo.phys.virginia.edu/classes/252/Rutherford_Scattering/Rutherford_Scattering.html

Robert Millikan discovers the weight of an electron using charged oil drops

Jan 1, 1909

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Niels Bohr makes model of atom with electrons based on different energy levels outside of the nucleus

Jan 1, 1922

http://www.pbs.org/wgbh/aso/databank/entries/bpbohr.html

James Chadwick discovers the neutron

Jan 1, 1932

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