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  -500-400 BC
 -Aristotle says that Matter is created by four different elements. The elements being Earth, Fire, Water, and Air.
- 
  
  -500-400 BC
 -Democritus states that Matter is created by invisible particles called "atoms."
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- 
  
  -1600-1700's
 -England
 -John Dalto is called "The Father of Atomic Theory"
 states that :
 1. atoms are small hard spheres.
 2.atoms are invisible.
 3.atoms of the same element are the same.
 4.atoms of different elements are different.
 5.atoms combine in small whole number ratios.
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  -1800-1900
 -England
 -Discovered the electron Cathode Ray Tube. Used the "Plum Pudding" example.
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  -1900's
 -England
 -Gold Foil Expirament. Discovered the Nucleus.
 -Nucleus:very small, very dense.
- 
  
  1908
 Chicago
 discovered the charge and mass of an electron.
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  1930's
 Denmark
 Planetary Model: electrons orbit the nucleus just like planets orbit the sun.
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  -1932
 -Cambridge
 -discovered the neutron.