VSEPR Boxes - A large model set is used to construct each of the 3-D VSEPR shapes. The models can then be placed inside of large (about two feet tall) cardboard polyhedra of the appropriate shape. Helps students make the connection between molecular shapes and their geometric names.

Curriculum Notes 

This demo is used when the VSEPR theory for predicting molecular shapes is being introduced. Allow at least 15 minutes for this demo. Most instructors like to incorporate this demo into their expository lecture on VSEPR so it can take much longer.

Lead Time 
One day of lead time is required for this project.

Some students have difficulty visualizing the three-dimensional VSEPR molecular structures and assigning names to them. This demonstration can help them in two ways. First, they can see the structures constructed and displayed in three dimensions rather than as two-dimensional projections such as those that appear on a printed page. Second, since the names of the structures are actually names of polyhedra, this demonstration helps them to correlate the molecular structures to those polyhedra.

  • Large ball-and-stick molecular model kit
  • VSEPR polyhedral box set

As each of the three-dimensional VSEPR shapes (tetrahedral, trigonal bipyramidal, rocker, trigonal pyramidal, octahedral, and square pyramidal) are discussed in your lecture, construct a model of them from the large scale model kit and place it into the specially constructed polyhedral box that it fits. 

© Copyright 2012 Email: Randy Sullivan, University of Oregon Chemistry Department and UO Libraries Interactive Media Group