Chemistry ch 13

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Chemistry ch 13
2011-02-13 16:00:15

molecular structure and shape
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  1. the behavior of an atom is most determined by
    its electron configuration
  2. the behavior of a molecule is most determined by
    the molecule's shape
  3. how do you determine a molecule's shape?
    look at the distribution of electrons in the molecule, using a Lewis dot diagram
  4. for all atoms that form covalent bonds, the outermost energy level must
    have a total of 8 electrons
  5. Which covalently bonded electrons don't have 8 electrons in the outermost level?
    • hydrogen
    • lithium
    • beryllium
    • boron
    • groups 1, 2, & 13
  6. lone pairs
    unshared pairs of electrons
  7. double bonds
    share 2 electron pairs
  8. each bond of shared electrons and each pair of unshared electrons in the outermost energy level form a
    • charge cloud
    • repels other charge clouds
    • this is the electrostatic repulsion of 2 or more negative charges
  9. what determines the arrangement of orbitals?
    electrostatic & Pauli exclusions
  10. orbital arrangement determines
    molecular shape
  11. why do electron pairs spread apart as far as possible in a molecule to
    minimize repulsion forces
  12. shape 1
    • if there are 2 pairs of shared electrons around a central atom, the shared pairs will be on opposite sides of the central atom
    • Linear molecule
    • the angle between the shared pairs is 180
  13. shape 2
    • if there are 3 pairs of shared electrons around a central atom, a trigonal planar molecule is formed
    • the angle between the pairs is 120
  14. shape 3
    • if there are 4 pairs of shared electrons around a central atom, a tetrahedral molecule is formed
    • angle is 109.5
  15. shapes 1, 2, and 3 have
    no unshared pairs of electrons
  16. the repulsion between unshared pairs of electrons is
    stronger than the repulsion between shared pairs
  17. shape 4
    • if there are 3 shared and 1 unshared pair of electrons around a central atom, a pyramidal molecule is formed
    • angle is 107
  18. shape 5
    • if there are 2 shared and 2 unshared pairs of electrons, an angular or bent molecule is formed.
    • angle is 104.5
  19. shape 6
    • if the molecule is closed, a cyclic molecule is formed
    • a ring- closed
  20. molecules ehich contain atoms bonded by polar covalent bonds will also be polar, unless
    the molecules have symmetry, which makes the molecule non-polar
  21. hybrid orbitals
    form when s & p orbitals overlap in a covalent bond
  22. sigma bond
    when 2 hybrid orbitals from 2 different atoms form a bond by overlapping directly on a bond axis
  23. pi bond
    when 2 hybrid obitals from 2 different atoms bond by overlapping sideways, a pi bond is formed
  24. a sigma bond forms a
    single bond
  25. a sigma bond and a pi bond form a
    double bond
  26. a sigma bond and 2 pi bonds form a
    triple bond
  27. a single bond is a
  28. a double bond is a
    sigma & pi
  29. a triple bond is a
    sigma & 2 pi
  30. what makes benzene (C6H6) very stable?
    overlapping of pi bonds cause the electrons to be shared all around the ring- these are delocalized pi electrons
  31. conjugated system
    when multiple pi orbitls overlap
  32. catenation
    the ability of all carbon atoms to form chains of varying lenghts
  33. simple hydrocarbons
    • use a stem & -ane
    • contain only single bonds
    • saturated compounds
  34. double bonded hydrocarbons
    same stem, add -ene
  35. triple bonded hydrocarbons
    same stem, add -yne
  36. isomers
    2 or more compounds which have the same molecular formula but have different structural formulas
  37. structural isomers
    differ only in the position of the carbon atoms in relation to each other
  38. positional isomers
    differ only in the relative position of a double or triple bond between carbon atoms
  39. functional isomers
    • contain atoms besides carbon and hydrogen
    • named based on the position of their new atoms
    • the new atoms form "functional groups"
  40. functional groups
    • ex: The alcohol group- OH
    • when organic compounds contain an alcohol groupd, they end in -ol
  41. geometric isomers
    composed of the same atoms bonded in the same order but with different order around a double bond
  42. cis
    on the same side as the double bond
  43. trans
    on the opposite side of the double bond
  44. cyclic
  45. linear
    • bent
    • 104.5
    • pyramidal
    • 107
  46. tetrahedral