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INTERMOLECULAR FORCES

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INTERMOLECULAR FORCES. Chap. 13: Day 2. Generally strongest “Interparticle” Ionic Bond Ion-ion force Metalic bond Electronic force. Generally weaker “intermolecular forces” Covalent bonds Polar molecules Dipole forces Nonpolar molecules London Disperson Induced dipole forces. - PowerPoint PPT Presentation
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INTERMOLECULAR FORCES Chap. 13: Day 2
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  • INTERMOLECULAR FORCESChap. 13: Day 2

  • Type of Bond determines ForcesGenerally strongestInterparticleIonic BondIon-ion force

    Metalic bondElectronic force

    Generally weakerintermolecular forcesCovalent bondsPolar moleculesDipole forcesNonpolar moleculesLondon DispersonInduced dipole forces

  • Melting PointEnergy needed over come the intermolecular forces between molecules in the solid phaseTemperature at which molecules in a solid gain enough potential energy to change position (become L)

  • Boiling PointEnergy needed over come the intermolecular forces between molecules in the liquid phaseTemperature at which molecules in a liquid gain enough potential energy to change position (become gas)

  • POLAR vs NONPOLAR

    *

    Molecular PolarityMolecules will be polar ifa)bonds are polar ANDthe molecule is NOT symmetric

    *

    Polar or Nonpolar?Compare CO2 and H2O. Which one is polar?

    *

    Polar or Nonpolar?Consider AB3 molecules: BF3, Cl2CO, and NH3.

    *

    Molecular Polarity, BF3 B atom is positive and F atoms are negative.BF bonds in BF3 are polar. But molecule is symmetrical and NOT polar

    *

    Molecular Polarity, HBF2B atom is positive but H & F atoms are negative.BF and BH bonds in HBF2 are polar. But molecule is NOT symmetrical and is polar.

    *

    Is Methane, CH4, Polar?Methane is symmetrical and is NOT polar.

    *

    Substituted EthyleneCF bonds are MUCH more polar than CH bonds. Because both CF bonds are on same side of molecule, molecule is POLAR.

  • NONPOLAR MoleculesWhat causes the differences in intermolecular forces between molecules?Why do the intermolecular forces vary between nonpolar molecules?

  • LiquidSolidWHY?

  • Bigger Molecules interact more

  • DISPERSION FORCENonpolar Molecules

  • POLAR MoleculesWhy do the intermolecular forces vary between polar molecules?

    *

    Molecular PolarityMoleculessuch as HCl and H2O can be POLAR (or dipolar). They have a DIPOLE MOMENT. The polar HCl molecule will turn to align with an electric field.

  • DIPOLE FORCEPolar Molecules

  • More polar stronger force

  • Why different?liquidgas

  • ?

  • SOME POLAR MoleculesHave specialDipole force with HydrogenHYDROGEN FORCE orHYDROGEN BOND

  • HYDOGEN BOND NEED TO BE POLARH is attached to N, F, or O

  • ALL molecules have LONDON DISPERSION force

  • Graphing: Intermolecular ForcesSee handout4 different FamiliesBoiling point vs periodBoiling pointperiod100 k400 k26


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