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  Home > JCE Print > Journal of Chemical Education > Issues > 2005  > March  >
In the Classroom
Simple Dynamic Models for Hydrogen Bonding Using Velcro-Polarized Molecular Models
Emeric Schultz
Department of Chemistry, Bloomsburg University, Bloomsburg, PA 17815
Cover
March 2005
Vol. 82 No. 3
p. 401
Abstract
This article describes the use of models that dynamically illustrate the unique characteristics of weak intermolecular interactions, specifically hydrogen bonds. The models clearly demonstrate that H-bonds can break and reform while covalent bonds stay intact. The manner in which the models form and break H-bonds reflects the geometric and statistical manner in which H-bonding actually occurs and is not contrived. The use of these models addresses a significant area of student misconceptions. The construction of these molecular models is described. The materials required are easily obtained wooden ball knobs, Styrofoam balls, or CPK models along with Velcro adhesive patches. Molecular models of water and other substances can be made to give polarized molecular models. The polarization is reflected in patches of Velcro that are placed in structurally appropriate positions on the models in proportion to the partial charge on the atoms in the molecules. When collections of various models are shaken gently in a container, the expected H-bonds are formed; upon vigorous shaking the H-bonds are broken. This can be repeated over and over. The use of a blower system to directly visualize the dynamic formation of homonuclear as well as heteronuclear H-bonds with Styrofoam models is described.
Supplement
A video of the demonstrations is available.
*  Contents JCE2005p0401W.wmv (Windows Media Player)
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JCE2005p0401W.wmv
More Information
*  Citation
 Schultz, Emeric. J. Chem. Educ. 2005 82 401.
*  Keywords
 Demonstrations; Intermolecular Forces; Molecular Properties / Structure
*  History
 Created:
Last Updated:		 February 2, 2005
February 16, 2005
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