It is not often realized by chemists that the special theory of relativity is behind several aspects of quantum chemistry. The Schrdinger equation itself is based on relations between space-time and energy-momentum four vectors. Electron spin is, of course, the most obvious manifestation of relativity. The chemistry of some heavy elements is…

Nanotechnology is viewed by those in favor of its development in two different ways, and the divide is not recent. This article describes the origins of the differing visions of nanotechnology and examines their broader impacts. The typical history of the field tells nothing about these differing visions, which perhaps misleads. At least two…

In the first phase of the research project Nanotechnologies for Tomorrow's Society (www.nanosoc.be), the research consortium explored a variety of futuristic visions or technoscientific imaginaries. This exploration took the form of a Policy Delphi, adapted to the particular objective of jointly constructing nano-imaginaries, taking participants'…

Supplies information to answer typical student questions relating to the significance of "plus" and "minus" superscripts used for electronic states of linear molecules. (SK)

The story of researcher Joseph V. Smith's solution to the chemical structure of a zeolite known as boggsite is presented. The value of the solution and the use of boggsite are discussed. (CW)

An introductory undergraduate physical organic chemistry exercise that introduces the harmonic oscillator's use in vibrational spectroscopy is developed. The analysis and modeling exercise begins with the students calculating the stretching modes of common organic molecules with the help of the quantum mechanical harmonic oscillator (QMHO) model.

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)

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…

Provides a set of instructions for writing Lewis octet structures which incorporates a simple rule called the "6N+2 Rule." Discusses the importance of these structures in elementary chemistry, biochemistry, and organic chemistry courses. Also discusses non-octet structures and how they are characterized. (JM)

Discussed are the mechanisms of nuclear magnetic relaxation, and applications of relaxation times. The measurement of spin-lattice relaxations is reviewed. It is stressed that sophisticated techniques such as these are becoming more important to the working chemist. (CW)

Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)

Self-assembly or spontaneous assembly is a process in which materials build themselves without assistance. This process plays a central role in the construction of biological structures and materials such as cells, viruses, and bone, and also in abiotic processes like phase transitions and crystal formation. The principles of self-assembly help…

Described is an experiment which illustrates valence isomerization, the trapping of a reactive intermediate and retrosynthetic analysis applied to the Diels-Alder reaction. Included is a background discussion, experimental procedures, and a discussion of the analysis. (CW)

Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

Compares the similar mathematical problems of molecular vibrational calculations (at any intermediate level of sophistication) and molecular orbital calculations (at the Huckel level). Discusses how the generalizations of Huckel treatment of molecular orbitals apply to vibrational theory. (TW)