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Period: 400 BCE to 460 BCE
Democritus
Developed the concept of the Atom. He thought that everything in the Universe is made up of Atoms. Democritus thought they were the building blocks that were indestructible and indivisible. <img src="http://thehistoryoftheatom.weebly.com/uploads/2/1/6/1/21614116/5984852.gif" alt="Image result for democritus model of atom"/> -
Period: to
John Dalton
Thought that all matter was composed of Atoms. He also thought that all Atoms were identical, but in different materials they would be different sizes and mass. John Dalton thought they were the building blocks that were indestructible and indivisible. <img src="https://image.slidesharecdn.com/daltonandbohr-chemistrypro-120914140152-phpapp02/95/dalton-and-bohr-chemistry-pro-5-728.jpg?cb=1347631348" alt="Image result for dalton model of atom"/> -
Period: to
Dmitri Mendeleev
Dmitri made the Periodic Table of the Elements. He was arranging the cards into Atomic number order, while he was doing that he found the Periodic Law. <img src="https://s3.amazonaws.com/s3.timetoast.com/public/uploads/photos/9479873/slide_11.jpg?1485849218" alt="Image result for dmitri mendeleev model of the atom"/> -
Period: to
Max Planck
Created the Quantum Theory of Energy. His work helped understand the atomic and subatomic processes.
<img src="http://theatomictheoryproject1.weebly.com/uploads/9/9/0/5/9905782/6514949_orig.gif" alt="Image result for max planck atom model"/> -
Period: to
Eugene Goldstein
Goldstein discovered canal rays aka " Kanalstrahlen". These are positively charged ions. Because of this, he is credited to the discovery of protons.
<img src="http://3.bp.blogspot.com/-AAOt7T6BJdU/T_8UBhpFo7I/AAAAAAAAABs/YZDVK73QMpc/s1600/i53846927._msw565h424_szw565h424_.jpg" alt="Image result for eugene atomic model"/> -
Period: to
J.J. Thomson
Discovered the electron while experimenting with crookes, cathode ray. He discovered negatively charged particles.
<img src="https://d2gne97vdumgn3.cloudfront.net/api/file/c3zQ78mbQmvtP5li9wUw" alt="Image result for jj thomson model"/> -
Period: to
Robert Millikan
Millikan did an oil drop experiment that helped idenitfy the charge of an electron, which contributed greatly to our understanding of the structure of the atom and atomic theory.
<img src="http://creating.pbworks.com/f/p281.gif" alt="Image result for robert millikan theory"/> -
Period: to
Ernest Rutherford
discovered molecules, atom mainly empty space. Made it by Plum Pudding Experiment.
<img src="https://image.slidesharecdn.com/sandeep-160204103746/95/rutherford-atomic-model-8-638.jpg?cb=1454671737" alt="Image result for ernest rutherford atomic theory"/> -
Period: to
Niels Bohr
Niels Bohr made a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities.
<img src="https://cdn1.byjus.com/chemistry/wp-content/uploads/2015/12/2301.png" alt="Image result for niels bohr atomic theory"/> -
Period: to
Erwin Schrodinger
Took Niels Bohr theory one step farther. What he did was mathematical equations to describe the finding of an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom.
<img src="http://4.bp.blogspot.com/-LYf_1bY_UWs/TsslYcrsTpI/AAAAAAAAALE/QeGoBoWQKjw/s1600/Schrodinger.jpg" alt="Image result for erwin schrödinger atomic theory"/> -
Period: to
James Chadwick
Discovered the Neutron by finding a very energetic stream of radiation.
<img src="http://jameschadwickatomictheory.weebly.com/uploads/1/3/8/1/13818922/3751456.gif?1348242737" alt="Image result for james chadwick atomic theory"/> -
Period: to
Werner Heisenberg
Heisenberg used the quantum mechanics theory to discover allotropic forms of hydrogen.
<img src="https://sites.google.com/site/anatomsstory/_/rsrc/1472871514206/1927---werner-heisenberg/electron.png?height=198&width=320" alt="Image result for werner heisenberg model"/>
