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Jan 1, 1000
Alchemy
alchemy
1000-1650
attempted to change lead and other metals into gold, and tried to discover an elixir which would prolong life. google.com for picture -
periodic table
periodic table
Gay-Lussac, J.L. (1778-1850)
Discovered boron and iodine. Discovered acid based indicator. -
classifying minerals
Berzelius J.J. (1779-1850)
Classified minerals according to their chemical composition. Discovered and isolated many elements (Se, Th, Si, Ti, Zr). http://chemistry.about.com/cs/history/a/aa020204a.htm -
Dalton's Atomic Theory
Dalton A chemical reaction is a rearrangement of atoms. )
Stated that:
1) All matter is made of atoms. Atoms are indivisible and indestructible.
2) All atoms of a given element are identical in mass and properties
3) Compounds are formed by a combination of two or more different kinds of atoms.
4) A chemical reaction is a rearrangement of atoms. Picture found on: http://www.rsc.org/chemsoc/timeline/pages/1803.html -
Creation of the first Periodic table
Mendeleev
Mendeléev, Dmitri (1834-1907)
Discovered periodicity of the elements. Compiled the first Periodic Table with elements arranged into 7 groups (1869). Picture found on google.com -
Elements
Becquerel
Becquerel, H. (1851-1908)
Discovered radioactivity of uranium and deflection of electrons by magnetic fields and gamma rays. Nobel Prize in 1903 -
Thomson's Atomic Model
Thomson Thomson created a model of the atom as a sphere of positive matter with electrons positioned based on electrostatic forces. -
Rutherford
Rutherford
Rutherford overturned Thomson's atom model in 1911 with his well-known gold foil experiment in which he demonstrated that the atom has a tiny, massive nucleus.
picture found on google.com -
Bohr
Bohr Acknowledged that electrons give or take energy only when they change their energy levels. If the electron gains energy, it would leap a level further from the nucleus, if it lessens in energy, the electron would fall a level closer to the nucleus.
