MOLECULAR MODEL KITS – THE STRUCTURE OF HYDROCARBON MOLECULES
Purpose: To use molecular model kits to build and study the structure of various hydrocarbon
molecules.
Materials: 2 molecular model kits (Work in groups of 3 or 4)
Method: First of all, organize your molecular model kit by picking out all of the following parts
that you will need. Other classes use these kits so the parts often get mixed up
between the bags. If you are missing any parts, obtain them from the leftover piles of
other groups.
32 hydrogen white - 1 projection
16 carbon
black - 4 projections
43 green plastic tubes to represent single bonds
5 white flexible rubber tubes – use two of these for each double bond
- use three of these for each triple bond
Please note that there will be other parts in the kit that you will not be using. They are
used by other classes that build different molecules.
Procedure, Observations and Conclusions
PART ONE: Homologous Series
1) Construct, draw the condensed structural diagram and name the following 4
compounds.
Chemical Formula
Condensed Structural
Diagram
Name
CH4
C2H6
C3H8
C4H10
1) How does each molecule in the series differ from the next?
2) What is a homologous series?
3) Which one would you expect to have a higher boiling point? Explain. (See pages
545-546 for help.)
PART TWO: Isomers of C4H8
1) C4H8 has 5 isomers. Using your model kit, construct these isomers, draw their
condensed structural diagram and name. You may have to construct them one at a
time, depending on the size of your kit.
Isomer
1
Condensed Structural Diagram
Name
2
3
4
5
PART 3: Chemical reactivity
1) Draw the condensed structural diagram for the molecule in the space provided in the
table.
2) Construct a model of the molecule using the parts from the molecular model kit.
Refer to the condensed structural diagram to see how those parts should be
connected.
Then, show all four of your models (from PART THREE only) to your teacher and get
your sheet initialed in the appropriate space to signify that your models have been
checked.
A complete set of molecular models was built. ________ (Teacher must initial in this space.)
Hydrocarbon
butane
Condensed Structural Diagram
cyclobutane
2-butyne
trans-2-butene
Next, use your molecular models to help you answer the following questions:
1) Which one of the four hydrocarbon molecules has its carbon atoms arranged in a straight
line (i.e. they are linear)?
2) Which hydrocarbon would be more unstable (ie decompose more easily): butane? or
cyclobutane? (Note- Examine the models for these molecules. The hydrocarbon that is
more unstable has bonds in it which are more stressed i.e. the bonds are fixed in a
strained position.)
After answering the above questions, take your models apart and either return your model
kits to the teacher or do the bonus work described below.
___________________________________________________________________________
Bonus Work: For five bonus marks, complete the following by the end of this period. If you
haven’t finished the model by the end of the period, just show me the part that you have
completed and you can at least get some of the bonus
marks.
A) Make some Prozac for Mr. Giles. Prozac is the world’s leading antidepressant with
annual worldwide sales of about $1.2 billion. Build the molecular model for Prozac
by using the following diagram as a guide. (Use red for oxygen, blue for nitrogen and
green for fluorine.)