Exp 5: Molecular Models


This molecular model-building lab is designed to help you develop a mental model that gives a three-dimensional image to two-dimensional Lewis structures that you draw on paper. It will also help you get a better picture of the different kinds of isomers that are possible with some molecular formulas.

Procedure:

  1. Sketch the Lewis structure, then build the model of the molecules. Note if they are 3-dimensional, 2-dimensional or 1-dimensional in shape.

    a. methane ethane ethene ethyne
    b. cyclopentene 1-propanol 2-propanol NH3

  2. Name each of the following organic compounds, then draw out the structural formulas. Show how many different isomers are possible with each one.

    1. C2H5OH & C3H7OH

    2. C6H12 & C6H14

    3. C4H9OH & C5H11OH

    4. C2H4(OH)2 & C3H5(OH)3

    5. C2H6O & C3H6O

  3. Make a model of the organic acid you are assigned. Use the Merek Index to find the molecular and structural formulas. Sketch first and then build the model.

  4. Draw a Lewis structure for each of the following substituted hydrocarbons and state what class of organic compound each one is. Then make a model of each of them.

    1-butanol diethyl ether acetone ethanal
    formaldehyde dimethyl amine acetic acid ethyl acetate


Results & Discussion:

How does the three dimensional nature of an alkane change as double and/or triple bonds are formed.
Is there a formula for how the number of isomers for an alkane relates to the number of carbon atoms?


Gwen Sibert
Roanoke Valley Governor's School
gsibert@rvgs.k12.va.us
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