Unit 2

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Unit 2
2010-10-06 02:33:09

Density, Atomic Theory, & Nuclear
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  1. specific gravity
    • a measure of the mass of an object compared to the mass of equal volume of water
    • =density w/o units
  2. reasons for uncertainty for measurements
    • tolerance= construction of device
    • human error= incorrect usage of device
    • conditions= temperature, pressure, etc.
    • malfunctioning equipment
  3. J.J. Berzelius
    a Swedish chemist generally given credit for creating the modern symbols of elements
  4. atomic number = ? (the bottom number)
    # of protons = # of electrons
  5. Latin names for:
    • Sodium=Na, Natrium
    • Gold=Au, Aurum
    • Silver=Ag, Argentium
    • Potassium= K, Kalium
    • Lead=Pb, Plumbum
    • Antimony=Sb, Stibinite
    • Iron= Fe, Ferrum
    • Tungsten=W, Wolfram
    • Tin=Sn, Stannum
    • Copper=Cu, Cuprum
    • Mercury=Hg, Hydrogyrum
  6. Mixture
    • 2 or more elements or coumpounds physically joined
    • ex: Brass= Copper (Cu) + Zinc (Zn)
  7. Compound
    • 2 or more elements chemically bonded to one another
    • ex: H2O
  8. Mixtures: Two or more pure substances
    • a)uniform, constant composition Ex: salt water, shampoo
    • b)non-uniform, varying composition Ex: granite, sand
  9. Democritus
    • Greek philosopher: Matter is composed of indivisble particles called atoms
    • atomos = "inidivisible"
    • Plato & Aristotle disagreed b/c no evidence or experiments, he used theory
  10. Alchemy
    • 1. Elixir of life
    • 2. Transmutation: Lead into gold
    • shifted from thought to observation and experimentation
  11. Laws that John Dalton based his Atomic Theory on:
    • Laws Dalton based his Atomic Theory on:
    • Law of Conservation of Mass (Antoine Lavoisier): Mass is neither created nor destroyed Ex: 2H2+ O2=2H2O
    • Law of Constant Proportions (Joseph Proust): Compound always contains the same elements in the same proportions
    • Law of Multiple Proportions (John Dalton): ratio of masses will remain constant for each compund
  12. J.J. Thomson
    • -used a Cathode Ray (electrons) Tube and discovered the electron
    • -determined charge to mass ratio of electron
    • -cookie dough/ plum-pudding model, plums were the electrons
  13. Robert A. Millikan
    • -Oil-Drop Experiment
    • -determined charge of electron
  14. Ernest B. Rutherford
    • -gold foil/alpha scattering experiment
    • -discovered the helium nucleus, proton (contains most mass & is positive)
    • -"planetary" atom model (electrons orbit nucleus) but it is wrong
    • -first artificial transmutation
  15. Neils Bohr
    • -Bohr model
    • -only the H spectrum
    • -worked in Manhattan Project
  16. James Chadwick
    discovered neutron (late because w/no charge, it's hard to detect)
  17. a) nucleon?
    b) nuclide?
    c) radionuclide?
    d) nuclear binding energy?
    • a) a particle in the nucleus (neutron or proton)
    • b) nuclide=nucleus
    • c) unstable nucleus
    • d) a strong force that holds protons and neutrons together
  18. mass number = ?
    # of nucleons (neutrons+protons)
  19. the three hydrogen isotops
    • 11 H = protium
    • 21 H = deuterium
    • 31 H = tritium
  20. Henri Becquerel
    discovered radioactivity using photographic plates and uranium ore
  21. types of radioactivity
    • alpha: nucleus of helium atom 4,2 He (through paper)
    • beta: high speed electron emission from nucleus -1e (through 3mm Al)
    • gamma ray: photon of high enery light: 00Y (through 3cm Pb)
    • penetrating power: gamma>beta>alpha
  22. Stable nuclei
    • 1) greater binding energy per nucleon
    • 2) low atomic numbers with 1:1 ratio of neutrons to protons
    • 3) even number of both neutrons & protons
  23. Mass defect
    • where binding energy comes from
    • the total mass of the stable nuclei > the sum of the masses of nucleons
    • missing mass is converted to energy
    • E=mc2
  24. how to determine half life
    • No=how much
    • x=half lives
    • N/No=0.5x
  25. Transmutation
    • -Bombardment: bombard a target nucleus with other particle or nuclei
    • -product+nucleus->more than one product formed
  26. Fusion
    • -combining smaller nuclei to form larger nuclei
    • -which increases binding enery which increases stability
    • -reactions take place at high temp (thermonuclear reactions)
  27. Fission
    -large nucleus is broken into smaller nuclei + one or more neutron