Point Group I, II, and III is a series of programs for Mac OS and Windows designed to teach point group symmetry. The complete package of instructional programs and exercises is appropriate for upper-division undergraduate or graduate courses in inorganic or physical chemistry. The first two units can be used at whatever level symmetry elements are introduced. They were written for a sophomore inorganic chemistry course that follows an organic chemistry course taken in the first year.

Contents
Point Group I: Introduction to Point Group Symmetry Elements and Operations is a detailed presentation using images of hands and ethane in staggered and eclipsed conformations to describe the symmetry. This unit takes students approximately 45 minutes to complete. Color coding is used to help students learn the difference between symmetry elements (blue symbols and words) and symmetry operations (red symbols and words).

Point Group II: Counting Symmetry Elements provides an interactive template wherein the user enters the number of each symmetry element found in a species. When finished, the user can check the answers. The program indicates any errors and includes hints for common errors to assist the user. Users should have molecular models in hand. Three sample programs are included. The first is suitable for use with students who have a general chemistry-level understanding of VSEPR; the second assumes understanding of transition-metal complexes and isomerization; the third makes use of 3D models of works by Escher (1). A "Teacher Template" is included that allows the instructor to make custom-designed units using any species of chemical interest.

Point Group III: Point Group Nomenclature presents the user with a "decision tree" for assigning the name of the point group for a species. If the incorrect name is selected, the program indicates the branch in the tree where the wrong path was taken. Three sample programs using the same species as in the Point Group II sample programs are provided. A program for the instructor to generate a custom-designed unit is also included.

How to Use Point Group I, II, and III
Point Group I, II, and III have been used by the author in a student-centered instructional setting, where students use the programs and the instructor is available to help as required; and for independent study, with the instructor meeting with the students between units to clarify material as needed. Individual units can be employed in other settings. Although this package is intended for individual use, a few examples suitable for projection are included in Point Group I.

Hardware and Software Requirements
Hardware and software requirements for Point Group I, II, and III are found in Table 1. Point Group I, II, and III were created using Macromedia Director (2), QuickTime (3), Toolbook (4) (for the Windows version), and HyperCard (5) (for the Mac OS version).

Table 1. Hardware and Software Required for Point Group I, II, and III

Acknowledgments
Point Group I, II, and III were produced with support by the Camille and Henry Dreyfus Foundation, Inc. (1997-1999).

Literature Cited

1. Schattschneider, D.; Walker, W. M. C. Escher Kaleidocycles, revised ed.; Pomegranate Communications: Rohnert Park, CA, 1987.
2. Macromedia Director, version 6.5; Macromedia, Inc.: San Francisco, CA, 1998.
3. QuickTime, version 3.0; Apple Computer: Cupertino, CA, 1998.
4. ToolBook II, Instructor, version 6.0; Asymetrix: Bellevue, WA, 1998.
5. HyperCard 2.3.5; Apple Computer: Cupertino, CA, 1998.