Class 2 chem 403

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Class 2 chem 403
2010-05-26 11:06:18
chem laws chem

Stuff for exam one from class 2 chem 403
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  1. Define: atom
    Smallest unit of a substance
  2. Define: element
    substances consisting of a single kind of atom

    ex. oxygen, gold, iron
  3. Define: compound
    a substance formed by a combination of 2 or more elements bonded together
  4. Define: molecule
    2 or more atoms bounded together
  5. Laws:
    Conservation of mass
    the total weight of substances remains constant during a chemical reaction
  6. Laws:
    Law of definite composition
    In a compound the mass fraction of each element is always the same

    Ex. water always contains 88.8% oxygen and 11.2% hydrogen by mass
  7. Law of multiple proportions
    • ratio of elements in a compound.
    • Expressed as 2 or more elements to other are in a ratio of small whole numbers when 2 or more compounds are formed
  8. Atomic theory discovered by...
    John Dalton
  9. Atomic theory 4 parts:
    • 1. Matter is composed of atoms that cannot be created or destroyed
    • 2. Atoms of one element can not be converted in atoms of another element
    • 3. Atoms of an element are identical in mass and other properties but add different but add different from atoms of any other element (This meants that atoms of one element weigh more than the atoms of another element)
    • 4. Compounds result in from the chemical combination of a specific ratio of different elements
  10. what does the atomic number equal?
    equals the # of protons in the nucleus
  11. # of protons equals
    the # of electrons and the atomic #
  12. Isotopes have different numbers of...
  13. subscript equals
    number of protons
  14. superscript equals
    the # of PROTONS + # of NEUTRONS
  15. atomic mass is also called....
    atomic weight
  16. mass spectrometer measures
    relative abundance of different isotopes of an element is measured using an intrument
  17. Average atomic weight equals:
    the sum of isotope mass times abundance of isotope fro all naturally occurring isotopes