MCTP
Maryland Collaborative 
for Teacher Preparation

Molecular Modeling with "ball-and-stick" model kits

Thomas C. O'Haver
Department of Chemistry and Biochemistry
University of Maryland
College Park, MD 20742
(301) 4051831
to2@umail.umd.edu


NSF Cooperative Agreement No. DUE 9255745

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Chemistry 121/122                Name________________________________

          Molecular Modeling with "ball-and-stick" model kits

For this experiment you will work in pairs.  Pick a partner and unpack
your model kit.

1.  Why do you think the different types of atoms are given different
colors? Are these colors the real colors of these atoms, or just
arbitrary colors?

2. Locate on the periodic table in your textbook all the atom types
included in the kit.

3.  How many holes (for bonds) are there in these atoms?

                H            hydrogen             _____
                C            carbon                  _____
                O            oxygen                 _____
                Cl           chlorine                _____
                Br           bromine                _____

4.  Construct models for the diatomic molecules hydrogen (H2), chlorine
(Cl2), and hydrogen chloride (HCl).  What does the bond between the two
atoms represent; that is, what is the bond actually composed of?

5. Construct a model for water (H2O) and compare it to the "dot
structures" on page 34 of your textbook.  Is your water model actually
straight as suggested by the pictures on page 34?

6. What is the "octet rule" and how does it explain the tendency of
oxygen to form two bonds, whereas chlorine, for example, forms only one
bond?

7.  Construct models for methane (CH4) and for chloroform (CHCl3).
What shape is formed by the vertices of the molecule?

8. Construct models for ethane (C2H6), and propane (C3H8). Is there any
other way to construct these molecules?

9.  Construct a model for butane (C4H10).  Can you find more than one
way to construct a molecule with this formula?  How many?

10.  Ethanol is C2H6O.  Try to construct that molecule.  Can you find
more than one way to construct it?

10.  Some molecules contain so-called "double bonds".  Build models for
diatomic oxygen and for carbon dioxide.  How many double bonds do these
molecules have?

11.  If you wanted to make a model for Freon 11 (page 48), what element
is missing from your kit?  What element could you substitute, that
makes the same number of bonds as the missing element?

12.  Octane (found in gasoline) has 8 carbons and is one of the family
of hydrocarbons such as methane, ethane, butane, and propane.  What
formula would you predict for octane?


Bibliography

1. The Printice Hall Molecular Model Set for Organic Chemistry, 1994.

2. American Chemical Society, "Chemistry in Context: Applying
Chemistry to Society", Wm. C. Brown Publishers, 1994.