Atomic Theorists

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Atomic Theorists

• How we got to where we are now

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Law of Conservation of Mass

• Who Antoine Lavoisier
• Matter can't be created or destroyed
• When 1785
• Where France

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Law of Definite Proportions

• Who Joseph Proust
• Compounds Elements put together in
• fixed ratios of small whole
  numbers
• C O2 ? CO2
• When 1797
• Where France

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Law of Multiple Proportions

• Who John Dalton
• Two elements can form more than one compound
• The subscripts of the elements in the compounds
  will be small whole numbers.
• C O2 ? CO2
• C O2 ? CO
• Where England When 1803

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Who Aristotle
What All matter is a combination of fire,
air, earth or water When 350 B.C. Where
Greece
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Who Democritus

• When 400 B.C.
• Where Greece
• What Matter was made of indivisible
• substances he called atomos
• (1st talk of the atom)

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Who John Dalton

• What Solid Sphere Model (1st atomic theory)
• Elements are made up of indivisible particles
  called atoms
• Each element was composed of the same kind of
  atoms.
• Different elements were composed of different
  kinds of atoms.
• Compounds are composed of atoms in specific
  ratios.
• Atoms are not created or destroyed in a reaction.
• When 1805 Where England

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• Problems with Daltons Theory Today
• (issues that werent known about ..yet)
• Matter is composed of indivisible particles
• There are electrons, protons and neutrons
• All atoms of a particular element are identical
• There are isotopes
• 3. Different elements have different atoms
• Atoms combine in whole number ratios
• Atoms cant be created or destroyed
• Nuclear explosions destroy matter

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Who J.J. Thomson

• What Atoms aren't smallest particle
• Conducted experiment with a
• Cathode Ray Tube
• Particles had a negative charge
• (discovered electrons)
• Model plum pudding

When 1897 Where England
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Cathode Ray Tube
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Who Robert Millikan

• What
• Experiments to determine mass of electron
• Conducted the oil drop experiment
• Verified that electron is negatively charged
• 1.6 x 10 -19 coulombs
• No new model
• Where America When 1910

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Millikan Oil Drop Experiment
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Who Ernest Rutherford

• What
• Conducted Gold Foil experiment
• Proved nucleus is dense, positively charged core
  of atom
• When 1911
• Where America

• Model Stationary Planetary

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Rutherfords Experiment
Gold Foil Experiment
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Results of foil experiment if Plum Pudding model
had been correct.
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What Actually Happened
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Who Niels Bohr

• What Pulsating Planetary Model
• Electrons can move between energy levels
• When 1913
• Where Denmark

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There were many people involved with developing
the mathematical process to determine the path
of the electron. One of these men was
Schroedinger.
What pulsating orbital model
When 1926 Where Switzerland
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(No Transcript)
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Who James Chadwick

• What
• Confirmed existence of neutron
• No new atomic model
• When 1932
• Where England