-
465
Democritus Propes Matter Theory
Democritus proposed that matter exists in extremely small particles. He called these particles atoms. Democritus proposed this in 465 BC http://jeff560.tripod.com/images/democ1.jpg http://chemistry.about.com/cs/history/a/aa020204a.htm -
Berzelius's Atomic Theory
Berzelius proposed that atoms are spherical, the same size, and have different weights. He also stated that atoms joined together by an electrospherical reaction. http://www.rsc.org/images/Student_sheets_updated_tcm18-189669.pdf -
Dalton Proposes The Atomic Theory of Matter
The Atomic Theory states that all matter is made of atoms and atoms cannot be created or destroyed. Atoms of the same element have the same mass, volume, etc. and vice versa for atoms of different elements. The theory also states that atoms can join together to form compounds. http://chemistry.about.com/cs/history/a/aa020204a.htm http://www.rsc.org/images/Student_sheets_updated_tcm18-189669.pdf -
Mendeleev Devolps Periodic Table
Mendeleev is credited for devolping the periodic table we know today. Since new elements have been discovered the format has changed somewhat but Mendeleev is still credited with this event. http://www.ptable.com/Images/periodic%20table.png http://en.wikipedia.org/wiki/Periodic_table -
Thomson Discovers the Electrron
Thomsons main contribution to chemistry was the discovery of the electron and characterizing it as subatomic particle. Thomson along with Wilson are both credited for photographing the electron. Even thought Thomson had the scientific and photographic proof that electrons exsisted, he was afraid to tell the world because the atom was always thought to be a single solid particle. http://www.chemistryexplained.com/Te-Va/Thomson-Joseph-John.html http://www.rsc.org/images/Student_sheets_updated_ -
Rutherford Discovers Atoms Radioactivity And Creates Model of Atomic Theory
Rutherford is credited with discovering atoms radioactivity. Along with this he discovered that atoms having a positively charged core could reflect radiation back. Rutherford called this the necleus. http://www.chemistryexplained.com/Ru-Sp/Rutherford-Ernest.html http://www.rsc.org/images/Student_sheets_updated_tcm18-189669.pdf http://static.guim.co.uk/sys-images/Education/Pix/pictures/2009/2/9/1234184923217/Ernest-Rutherford-and-Hau-001.jpg -
Bohr Creates Model of Atom
Bohrs atom model stated most of the mass of an atom was in the necleus that contains the protons. Also electrons orbit the necleus. http://www.rsc.org/images/Student_sheets_updated_tcm18-189669.pdf -
Sir James Chadwick Discovers The Neutron
Chadwick discovered the Neutron in 1932. He recieved a nobel prize for his work. Chadwick replicated experiments by other chemists that believed another neutral particle existed in the necleus. Through this he discovered the neutron. http://chemistry.about.com/cs/history/a/aa020204a_3.htm -
Werner Heisenburg Proves Neutron Cannot Pair
Heisenburg proved that the neutron could not be proton-electron pairing. This proved the third part of an atom This was a major break through in chemistry because chemists could now use the neutron to bombard other atoms with the neutron
