Experimental Illustration of the Utility of Lewis Structures: An FTIR Experiment for Introductory Chemistry

Students in introductory chemistry are taught to draw Lewis dot structures, but are seldom provided with the opportunity to appreciate the predictive power of such a simple bonding model. An experiment is described in which students record the FTIR spectra of a series of organic liquids which contain a carbonyl group and to predict the strength of the carbonyl bonds based upon drawing and examination of various Lewis structures. Modern Fourier transform infrared spectrometers allow rapid collection of the data so that a single instrument serves an entire lab section. Students gain access and enjoy the use of a modern, state-of-the-art instrument.