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Time Line

Published on Nov 19, 2015

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PRESENTATION OUTLINE

1.

440 B.C.

  • Democritus
  • Atoms are small, hard particles
  • Atoms constantly move
  • All substances are made up of atoms
  • Atoms are "uncuttable"
Photo by tim caynes
2.

1803

  • Dalton
  • Atoms of different elements are different
  • Elements combine in specific propirtions
  • He conducted experiments in combining elements
  • Atoms of the same element are exactly alike
Photo by Wolfram Burner
3.

1897

  • Thomson
  • He conducted the cathode-ray tube experiment
  • There are small, negatively charged particles inside an atom
  • This theory of atomic structure led to the "plum-pudding" model
Photo by fritish
4.

1911 RUTHERFORD

  • There is a small, dense, positively charged nucleus
  • Atoms contain mostly empty space
  • He conducted the gold foil experiment
  • Electrons move in empty space in the atom
  • Most of an atom's mass is in the nucleus
Photo by tanakawho
5.

1913

  • Bohr
  • Electrons jump between levels from path to path
  • Electrons travel in definite paths
Photo by zen
6.

20TH CENTURY

  • Electron paths cannot be predicted
  • Electrons are found in electron clouds, not paths
Photo by Craighton Miller

Leta Lohrmeyer