Bond Lengths - Single, Double, or Triple Bonds

Two factors determine the lenth of a bond. These are: 1)the type of bond between the two atoms and 2) the types of atoms which make up the bond. The purpose of this exercise is to allow you to look at how the type of bond affects the bond length.

  1. Build and minimize ethane, ethene, and ethyne. Record the energy and for each.(Hint: in PC Model you can convert ethane to ethene by using the add bond function, then the Hadd function). For each of these, use query to determine the carbon-carbon bond length and the angle indicated in the diagram below.
  2. Do the carbon-carbon bond lengths get smaller or larger going from ethane to ethyne?
  3. What is the relationship between the bond length and the strength of the bond?
  4. Do the carbon-hydrogen bond lengths change significantly?
Compound Energy Carbon-Carbon Bond length Carbon-Hydrogen Bond length Bond angle
ethane





ethene





ethyne





Molecular structures of ethane, ethene, and ethyne





Problem contributed by: Luise E. Strange (DeKalb College)
Web implementation by: Luise E. Strange (DeKalb College)

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