Explores the question "Why are so many stationary states allowed by traditional quantum mechanics not realized in nature?" through discussion of classical observables and superselection rules. Three examples are given that can be used in introductory courses (including the fermion/boson property and the mass of a "nonrelativistic" particle). (JN)

Presents procedures for obtaining and examples of delta plots (a way of illustrating electron density changes associated with electronic excitation). These plots are pedagogically useful for visualizing simple and complex transitions and provide a way of "seeing" the origin of highest occupied molecular orbital (HOMO)-dictated carbonyl…

Describes software which demonstrates some features of three-dimensional protein structure on microcomputers. The program only displays the polypeptide backbone drawn through the alpha-carbon positions and is therefore much less sophisticated, but it has been used successfully during lectures on protein structure and as an adjunct to slides and…

Advantages of representing ternary and quaternary composition diagrams by means of rectangular coordinates were pointed out in a previous paper (EJ 288 693). A further advantage of that approach is that analytic geometry, based on rectangular coordinates, is directly applicable as demonstrated by the examples presented. (JN)

This article describes the experience of teaching structural bioinformatics to third year undergraduate students in a subject titled "Biomolecular Structure and Bioinformatics." Students were introduced to computer programming and used this knowledge in a practical application as an alternative to the well established Internet bioinformatics…

This paper argues in favor of Closed Captioned Video technology for incorporating nanotechnology as part of teaching science to English as a Second Language (ESL) students. Nanotechnology deals with particles with diameters 1-50 nm and provides a macro-context for science instruction. Closed Captioned Videos provide an effective tool for…

Discusses model studies aimed at elucidating various ways in which molecular oxygen interacts with metalloproteins. The focus is on the chemistry of iron(II) porphyrins and their adducts with nitrogenous bases, carbon monoxide, and dioxygen, which are most relevant to the functional proteries of the heme proteins, hemoglobin, and myoglobin. (JN)

Several chemical concepts can be visualized by using deformation density maps. They often present convincing experimental confirmation and they should be incorporated into the chemistry curriculum dealing with bonding and molecular structure. Examples of the maps and quantitative information derived from research studies are presented. (JN)

Compares linear-nonlinear and planar-nonplanar geometry through the valence-shell electron pairs repulsion (V.S.E.P.R.), Mulliken-Walsh, and electrostatic force theories. Indicates that although the V.S.E.P.R. theory has more advantages for elementary courses, an explanation of the best features of the different theories offers students a better…

Assigning "R" or "S" descriptors to chiral centers by inspection of a stereoformula often results in mistakes, especially when three-dimensional representations (with solid and dashed bonds for substituents pointing to front or rear) are used. Therefore, a method is presented that can be applied to all three-dimensional…

After noting the grounds for labelling structures as incorrect, the guidelines for selecting which Lewis structures are most important for a molecule are introduced. Several examples of appropriate Lewis structures and the fine structural predictions that are possible are included. (JN)

Discusses various ethylenediaminetetraacetate (EDTA)-type chelating agents found in ophthalmic products, personal care products, and disinfectants. Also discusses the properties and action of these EDTA agents. (JN)

A protein lacking one of the 20 common amino acids is a protein lipogram. This open-ended problem-based learning assignment deals with the evolution of proteins with biased amino acid composition. It has students query protein and metabolic databases to test the hypothesis that natural selection has reduced the frequency of each amino acid…

A computational experiment is described for the organic chemistry laboratory that allows students to estimate the relative strengths of the intramolecular hydrogen bonds of usnic and isousnic acids, two related lichen secondary metabolites. Students first extract and purify usnic acid from common lichens and obtain [superscript 1]H NMR and IR…

This is part two in a series on classroom demonstrations of polymer principles. Described is how large molecules can be assembled from subunits (the process of polymerization). Examples chosen include both linear and branched or cross-linked molecules. (RH)