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In 1808, John Dalton published a book about gas behavior. It also included his chemical atomic theory, pieces of which are still used by chemists today.
http://www.universaltoday.com/38193/john-dalton-atomic-theory/ -
Heinrich Geissler creates the first vacuum tube. The vacuum tube is used in many future chem experiments, especially those involving atoms.
http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.html -
Eugene Goldstein discovered positive particles by using a tube filled with hydrogen gas.
http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.html
http://www.desy.de/f/hera/fig/engl/proton-naif.gif -
Marie Curie discovered uranium and thorium. She then went on to discover two previously unknown elements, radium and polonium.
http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.html
http://www.chembase.com/gallery/23989/Uranium_low_enriched_ore.jpg -
Sir Joseph John Thomson discovered the electron.
http://chemistry.about.com/od/historyofchemistry/p/jjthomson.htm
http://3.bp.blogspot.com/_0Rgk0_Zbpr4/TJDChn_akLI/AAAAAAAAAXk/DHATutz440U/s400/atom-with-electrons.gif -
Robert Millikran discovered the mass of an electron by introducing charged oil droplets onto an electrically charged field. Through this experiement, he found the mass and charge of an electron.
http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.html -
Ernest Rutherford performs an experiment using gold foil and comes up with his atomic theory, which describes the atom as having a central positive nucleus surrounded by negative orbiting electrons.
http://www.rsc.org/chemsoc/timeline/pages/1911.html
http://www.rsc.org/chemsoc/timeline/graphic/1911_gfoil_02.jpg -
Niels Bohr applies quantum theory to Rutherford's atomic structure by assuming that electrons travel in stationary orbits defined by their angular momentum. This led to the calculation of possible energy levels for these orbits.
http://www.rsc.org/chemsoc/timeline/pages/1913.html -
