Emphasizes the role that crystallography plays and has played in building up the body of chemical fact. Shows how the teaching of much of this material is illuminated by reference to crystal structures and crystallochemical relationships in all areas of chemistry. Discusses close packing, silicate structures, and salt hydrates. (CW)

Describes current methods for the synthesis of DNA. Also describes the use of DNA as a highly specific molecular probe and as an agent for the mutation of genes. (DH)

Discusses the rationale for using photochemistry to merge descriptive chemistry and molecular orbital theory in first-year chemistry courses. Includes procedures and safety information for various activities, demonstrations, and experiments involving photochemical reactions. (DH)

Shows how to make stereo slides of three-dimensional molecular models. The slides have been used to teach chirality, conformational isomerism, how models and two-dimensional representations embody selected aspects of structure, and fundamentals of using the specific model set required in a particular organic chemistry course. (JN)

Proposes a simple experiment based on the procedure of Guggenheim and Smith for the determinatin of the dipole moments of two isomeric compounds in nonpolar solvents. Provides background information, laboratory procedures, sample data, results of least squares analysis and discussion of results. (JM)

Examines background of ideas against which Lewis's last researches were done, reflecting on his conduct of scientific research. Also analyzes Lewis's unique habit of writing research previews and indicates, through his research memoranda to the author, his intensity of research interest and activity during the last years of his life. (JN)

Suggests polymer topics for study in inorganic chemistry courses. Commercial materials (including list of inorganic compounds utilized in polymer industry), anchored metal catalysis, polymers modified or formed by coordination, polysiloxanes, phosphazene or phosphonitrilic halide polymers, and hetergeneous polymerization catalysts are considered.…

Describes common artificially produced organized media such as colloids, surfactants, and polymers and their usefulness in studying complex biochemical processes. Discusses selected recent photophysical and photochemical exploitations of these systems, including artificial photosynthesis, in situ generation of colloidal gold and platinum,…

Discusses the confusion and erroneous conclusions that can result from the overuse and misuse of the circle notation to represent aromaticity in polycylic aromatic hydrocarbons. Includes nature of the problem, textbook treatment, and a possible compromise method of representation. (Author/JN)

Describes an experiment providing an experimental introduction to vibrational spectroscopy and experience in using an elementary vacuum line. The experiment, using a gas cell charged with methanol, is completed in a three-hour laboratory period and is directed toward understanding vibrational spectroscopy rather than the diagnostic value of the…

Mechanical properties (stress-strain relationships) of polymers are reviewed, taking into account both time and temperature factors. Topics include modulus-temperature behavior of polymers, time dependence, time-temperature correspondence, and mechanical models. (JN)

Demonstrates how the incorporation of relatively low amounts of ionic material into nonionic polymers affects the structure and properties of these polymers. The extent to which properties are altered depends on dielectric constant of the backbone, position and type of ionic group, counterion type, ion concentration, and degree of neutralization.…

The application of molecular mechanics (a nonquantum mechanical method for solving problems concerning molecular geometries) to calculate force fields for n-butane and cyclohexane is discussed. Implications regarding the stable conformations of the example molecules are also discussed. (Author/SK)

Describes features of a new type of chemical database which provides the ability to search for substances sharing particular structural characteristics. Search concepts are examined in detail, and menu selection of "screens," system commands, and interpretation of results (which appear in the form of chemical bond structures) are…

Reports on the human immunodeficiency virus which causes disease that culminates in the Acquired Immunodeficiency Syndrome (AIDS). States that the key to prolonging life and health is early detection of the infection which usually occurs years before symptoms emerge. (RT)