3-2: Discovering Atomic Structure

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3-2 Discovering Atomic Structure

• By Ms. Pacheco

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Michael Faraday

• 1839 (English)
• Faraday suggested that atoms of different
  elements behave differently due to electricity,
  though he didnt know exactly how
• He was right atoms contain particles that have
  an electric charge

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Ben Franklin

• Faraday wasnt the first to study electricity,
  though
• Franklin was a statesman and a scientist
• Famous for his kite and key experiment
• Said that objects had either a positive or
  negative charge
• Like charges repel opposite charges attract

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A statue of Franklin at the University of
Philadelphia
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Franklin was also

• An inventor
• A printer
• A philosopher
• A musician
• An economist
• The only person to sign
• The Declaration of Independence
• The Treaty and Alliance of France
• The Treaty of Paris
• The Constitution

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One last note on Franklin

• He loved turkeys
• He even used them in his experiments with
  electricity!!!!!
• He actually wanted the national bird to be a
  turkey!

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• Ben Franklin On The Turkey As National Bird
• "For my own part I wish the Bald Eagle had not
  been chosen the Representative of our Country. He
  is a Bird of bad moral Character. He does not get
  his Living honestly. You may have seen him
  perched on some dead Tree near the River, where,
  too lazy to fish for himself, he watches the
  Labour of the Fishing Hawk and when that
  diligent Bird has at length taken a Fish, and is
  bearing it to his Nest for the Support of his
  Mate and young Ones, the Bald Eagle pursues him
  and takes it from him.
• "With all this Injustice, he is never in good
  Case but like those among Men who live by
  Sharping Robbing he is generally poor and often
  very lousy. Besides he is a rank Coward The
  little King Bird not bigger than a Sparrow
  attacks him boldly and drives him out of the
  District. He is therefore by no means a proper
  Emblem for the brave and honest Cincinnati of
  America who have driven all the King birds from
  our Country....
• "I am on this account not displeased that the
  Figure is not known as a Bald Eagle, but looks
  more like a Turkey. For the Truth the Turkey is
  in Comparison a much more respectable Bird, and
  withal a true original Native of America... He is
  besides, though a little vain silly, a Bird of
  Courage, and would not hesitate to attack a
  Grenadier of the British Guards who should
  presume to invade his Farm Yard with a red Coat
  on."
• --Benjamin Franklin, in a letter to his daughter

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Can you imagine?!?
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J.J. Thomson

• 1896 (English scientist)
• Using cathode ray tubes, discovered that atoms
  contained a negatively charged particle that he
  will call the electron

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Robert Millikan

• 1909 (American physicist)
• Using an oil drop experiment, calculated the
  charge and mass of a single electron

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Henri Becquerel

• 1896 (French physicist)
• Accidentally discovered radioactivity (the
  emission of radiation from an element)

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Becquerels First Radiograph
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Becquerels worked with and shared the 1903 Nobel
Prize in Physics with

• Pierre and Marie Curie
• Both would later die from exposure to radiation

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Ernest Rutherford

• 1909 (New Zealand scientist)
• Performed an alpha scattering experiment, using
  gold foil

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Ernest Rutherford

• Proved the existence of a positively changed
  particle in an atom, that he called a proton
• Said that the core of the atom (he called the
  nucleus) contains all of the mass and all of the
  positive charge

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Niels Bohr

• Danish (1913)
• electrons travel around the nucleus in orbits
  (sun-planet model)
• Electrons could drop from higher energy level to
  a lower energy level, emitting

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First X-ray (1896)