Chem 001 Exam Dates

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Chem 001 Exam Dates

• Friday 9/25 1010-11am 121 Sparks?Friday 10/30
  1010-11am 121 Sparks?Wednesday 12/2 1010-11am
  121 Sparks
• In class
• Multiple Choice

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Structure of Atom

• Atoms have a small nuclei (size speck) and a
  large fuzzy electron cloud (size building)
• Most of the atomic volume is empty space
• Nuclei is positively charged

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Can We See Atoms?

• How do we know atoms exist?
• How big are atoms compared with light
• Scanning Probe Microscopy
• Nickel atoms
• stm12.jpg
• Atomic Fly-By Movie (311 kB)

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Why Do We Care About Atoms?

• Different atoms have different structure
• This is what makes iron iron and carbon carbon

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Atoms

• First thought to be hard and indivisible
• Evidence Matter is electrical
• Electrolysis of Water and Fuel Cell Operation

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Cathode Rays

• Evidence of electrons
• ChemTeam Thomson's Cathode Ray Tube
• Now negative electrical particle discovered
• Millikan electron charge
• Goldstein positive particles

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Radioactivity

• Spontaneous emission of radiation from unstable
  elements
• www.webelements.com
• Alpha particles
• Positive, four times mass of hydrogen atom
• Beta particles electrons
• Gamma rays not charged

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Rutherford Nuclear Model

• Rutherford's Gold Foil Experiment
• Nucleus very small compared with whole atom

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Subatomic ParticlesBuilding Blocks for Atom
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Bohr Model of the Atom

• The Electric Force
• Small nucleus surrounded by orbiting electrons
• Nucleus composted of protons and neutrons
• Not entirely correct, but very useful

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Isotopes

• Number of neutrons in nuclei may vary
• Hydrogen, deuterium, tritium

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Atomic Spectra

• Spectroscopy
• Study light given off by atoms and other species
• Rainbow electromagnetic spectrum
• Demo colors from elements
• Fireworks