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The History of the Atom Timeline
This timespan shows the development of the atomic theory over time and the scientists who proposed these theories. -
John Dalton Proposes an Atomic Theory
John Dalton proposes the atomic theory that says that atoms cannot be divided, all atoms of the same elements are the same, an atom cannot have its element changed by a chemical reaction, and that compounds are made when multiple of the same atoms are put together in a certain ratio. (http://chemed.chem.purdue.edu/genchem/history/dalton.html) -
JJ Thompson Atomic Theory
Thompson proposed that atoms were made up of negatively charged electrons that were balanced out with a positive charge, he called his model the plum pudding model because it was similar to the design of a plum pudding. (http://www.universetoday.com/46886/bohrs-atomic-model/) -
Marie Curie Wins her First Nobel Peace Prize
Marie Curie figured out that the placement of atoms does not affect the amount of radioactivity in something but that the radioactivity is in the atoms themselves.
(http://www.atomicheritage.org/profile/marie-curie) -
Rutherford's Experiment
Rutherford found evidence the challenged Thompson's model so he designed an experiment, he put up a thin sheet of gold foil and shot particles at it, if Thompson's theory was correct then the particles would all pass through the foil, however some of the particles were deflected, Rutherford hypothesized that atoms had mostly empty space with a positive charge in the middle. (http://www.universetoday.com/46886/bohrs-atomic-model/) -
Neils Bohr's Atom
Bohr thought that the electrons in an atom moved in specific orbits around the atoms nucleus rather than in a random pattern the way that Rutherford suggested, his model looked similar to a solar system.
(http://www.universetoday.com/46886/bohrs-atomic-model/) -
James Chadwick's Discovery
James discovered the Neutron of the atom which was an important part in the fission of 235 uranium, because it helped explain the process of the different parts of the atom during fission. His model was the same one as Bohr's.
(http://www.tutorvista.com/science/chadwick-atomic-model)
