Infrared and Raman Spectroscopy: A Discovery-Based Activity for the General Chemistry Curriculum

A discovery-based method is described for incorporating the concepts of IR and Raman spectroscopy into the general chemistry curriculum. Students use three sets of springs to model the properties of single, double, and triple covalent bonds. Then, Gaussian 03W molecular modeling software is used to illustrate the relationship between bond vibrations and both IR and Raman spectroscopy. Students view the characteristic vibrations of C C, C=C, and C C bonds in propane, propene, and propyne molecules. Finally, students collect IR and Raman spectra of hexane, 1-hexene, and 1-heptyne. This series of activities is completed in the first semester of the general chemistry sequence following the development of Lewis structures and before the discussion of electro-negativity and bond polarity.