Atomic Theory

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Atomic Theory

• foldable

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Scientists

• Democritus
• Dalton
• Thompson
• Rutherford
• Bohr
• Schrodinger and Heisenburg

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Democritus

• Around 440 BC
• Greek Philosopher
• Called a particle that couldnt be cut atomos
  (which means not able to be divided)
• The word atom is from the Greek word atomos.

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John Dalton

• Late 1700s
• British chemist and school teacher
• Did experiments that led him to write his atomic
  theory
• All substances are made of atoms. Atoms are small
  particles of matter that cannot be created,
  divided, or destroyed.
• Atoms of the same element are exactly alike, and
  atoms of different elements are different.
• Atoms join with other atoms to make new
  substances

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J.J. Thompson

• 1897- British Scientist
• Discovered that there are small particles inside
  an atom-electrons
• Used cathode ray tube to find electrons
• Plum-pudding model

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Earnest Rutherford

• 1909 former student of Thompson
• Discovered the nucleus of an atom
• Said atom is mostly empty space.
• Electrons move around nucleus like planets around
  the sun.

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Neil Bohr

• 1913 Danish Scientist who worked with Rutherford
• Said electrons travel in definite path around
  nucleus at certain distances
• Said electrons can jump from level to level like
  rungs on a ladder

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Schrodinger and Heisenburg

• 20th century scientists
• Electrons do not travel in specific paths
• The path can not be predicted
• Say there are regions inside the atom where
  electrons are likely to be found
• These regions are electron clouds