Molecular Presentation Graphics Structures

Tel. 800-227-5558, 202-872-4363, fax 202-872-6067 A 3D visualization program, which is capable of rotating molecules with up to 32,000 atoms, for the Macintosh II. Molecular Presentation Graphics (MPG) for chemical structure drawing. ChemWhere for searching for MPG structures in word processing documents. Also, ACS is second party distributor for Alchemy, Chem3D Plus, and other software for PCs and Macintosh 11. 

The resonance concept indicates that the actual molecular structure lies somewhere between these various approximations, but is not capable of objective representation. The idea can be applied to any molecule, organic or inorganic in which and electron pair bond is present. The term resonance hybrid denotes a molecule that has this property. Such molecules do not vibrate back and forth between two or more structures, nor are they isotopes or mixtures. The resonance phenomenon is rather an idealized expression of an actual molecule that cannot be accurately pictured by any graphic device. 

For new or would-be users of models, I present in Chapter 11 an introduction to molecular modeling, demonstrating how modern graphics programs allow users to display and manipulate models and to perform powerful structure analysis, even on desktop computers. This chapter also provides information on how to use the World Wide Web to obtain graphics programs and learn how to use them. It also provides an introduction to the Protein Data Bank (PDB), a World Wide Web resource from which you can obtain most of the available macromolecular models. 

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