Atomic Structure- History and The Nucleus

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Atomic Structure- History and The Nucleus
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Philosophers and Scientists

• Know how the following contributed to the history
  of the atom
• Philosophers from History of the Atom video
• Empedicles
• Leucippus
• Aristotle
• Gassendi

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Modern Day scientists

• Dalton
• atoms could not be divided
• all elements of a given element are the same
• different atoms could join to form compounds
• Thomson
• the plum pudding model
• negatively-charged "plums surrounded by
  positively-charged "pudding
• Rutherford
• atom is made up of a central charge surrounded by
  a cloud of orbiting electrons
• Bohr
• electrons are in levels around the nucleus

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Next week
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Structure of the Atom
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Particle Charge Mass (atomic mass units) Location
Proton positive 1 nucleus
Neutron neutral Ø 1 nucleus
Electron negative - 0.0006 orbit, level, cloud
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• The nucleus
• the center of the atom composed of protons and
  neutrons
• 99.9 of the atoms mass is here
• about 100,000 times smaller than the entire atom
• the atomic number of an atom is the number of
  protons ( charged) in the nucleus
• The of electrons (- charged) equals the
  protons in a neutral atom.
• the atomic mass or mass number of an atom is the
  sum of the protons and neutrons

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• Isotopes
• atoms with the same number of protons (and
  therefore the same element) but with a different
  number of neutrons.

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