ATOMIC STRUCTURE

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ATOMIC STRUCTURE

• Scientists that changed our view of the atom

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Democritus

• Did not conduct any experiments
• All matter is made of atoms
• Atoms are indivisible and indestructible

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John Dalton

• John Dalton was born on September 6, 1766 in
  Cumbria, England.
• He provided us with the first concrete ideas
  about the atom.

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John Dalton His Experiment
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John Dalton

• Four points to his theory
• All matter is composed of atoms that are
  indestructible and indivisible
• Atoms of one element are all the same atoms of a
  different element are different (Au atoms are
  different from Ag atoms)
• Atoms cannot be changed into different atoms by
  chemical of physical changes (Pb atoms cannot be
  turned into Au atoms)
• All atoms are like Billiard Balls a solid,
  sphere
• Atoms react in whole numbers

6
JJ Thomson

• Joseph John Thomson was born in Cheetham Hill, a
  suburb of Manchester on December 18, 1856.
• He is given credit for the discovery of the
  electron.

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JJ Thomson His Experiment

• Cathode Ray Tube

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JJ Thomson His Experiment
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JJ Thomson

• 3 Points to his theory
• All gases had the same mass charge ratio
• All atoms contain small, charged particles
  called electrons
• The atom now looked like Plum Pudding

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Goldstein

• Eugene Goldstein was born in 1850 in Germany.

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Goldstein His Experiment

• Cathode Ray Tube

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Goldstein

• Major Point to his theory
• He is given credit for the discovery of a
  positively charged particle Proton
• The atom was still thought to resemble Plum
  Pudding

13
Millikan

• Robert Andrews Millikan was born on the 22nd of
  March, 1868, in Morrison, Ill. (U.S.A. )

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Millikan His Experiment

• Oil Drop
• Experiment

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Millikan

• 2 Points to his theory
• All electrons have the same mass
• About 1/2000 atomic mass unit
• All electrons have the same charge
• -1.6 x 10 -19 Coulomb
• The atom was still thought to resemble Plum
  Pudding

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Rutherford

• Ernest Rutherford was born August 30, 1871 in
  Nelson, New Zealand (one of 12 children)

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Rutherford His Experiment
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Rutherford

• 3 Points to his theory
• Most alpha particle went through Atom is
  mostly empty space (area of electrons)
• Some alpha particles bounced straight back
  atom has a solid mass (nucleus)
• Some alpha particles reflected nucleus is
  positively charged
• New Model Nuclear Model

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Schrödinger

• Erwin Schrödinger born August 12 in Vienna,
  Austria in 1887.

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Schrödinger His Experiment
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Schrödinger

• Major points
• Electrons do not follow fixed paths
• They move randomly in areas of probability
  (orbitals)
• There are specific energies associated with each
  orbital
• New Model
• Quantum Mechanical Model

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Chadwick

• James Chadwick was born in Cheshire, England, on
  20th October, 1891.

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Chadwick His Experiment
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Chadwick

• 2 Points to his theory
• Discovered the Neutron Same mass as a proton,
  but without a charge
• Mass could be converted into energy
• Model was still thought to resemble the Quantum
  Mechanical Model