SELF QUIZ

1. The molecules of NH₃ are: (What would have to change in the molecules to change the answer?)
    a. nonpolar
    b. polar

2. What is the shape of CH₄ molecules?
    a. angular
    b. triangular pyramidal
    c. flat triangular
    d. linear
    e. tetrahedral

3. Which of the following chemicals has the lowest boiling point: (What factors cause this to be so?)
    a. CO₂
    b. H₂O₂
    c. PbO₂
    d. SO₂
    e. SiO₂

CO₂ is a linear  and symmetric molecule, so that it is non-polar.  The resulting Van der Waal's bonds are the weakest of the various kinds of intermolecular bonds, giving it the lowest boiling point of the compounds listed.

4. The strongest bonding between particles (i.e., molecules, ions, atoms, etc.) is found in materials which are at room temperature.
    a. solids
    b. liquids
    c. gases

5. Which of the following would you expect to have polar linear molecules?
    a. CO₂
    b. H₂O
    c. ICN
    d. NaCl
    e. SiO₂
    f. SO₂

6. Alcohol evaporates more readily than water.
    Which has stronger intermolecular bonds?  water

    Which has the higher melting point?  water

    Which has the higher boiling point?  water

7. In water the interatomic bonds are (ionic/covalent/metallic) and the intermolecular bonds are (van der Waals/dipole-dipole/hydrogen).

8. What shape, polarity and intermolecular bond type do H₂S molecules have?

    They are bent (angular), polar, and have dipole-dipole bonds

9. What type of bonding attracts NaCl to H₂O?   Ion-dipole bonds

10. Put the following in order of increasing bond strength. (What factors caused you to select this order?)
        NH₃     N₂      NF₃

        N₂        NF₃    NH₃

          N₂ is non-polar and so has Van der Waal's, the weakest intermolecular bonding.
        NF₃ is a trigonal pyramid and polar, so has dipole-dipole bonds, the next strongest.
        NH₃ has N-H bonds and so has hydrogen bonds, the strongest of the three.

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E-mail instructor: Eden Francis

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