Quantification of a contaminant in water provides the first-year general chemistry students with a tangible application of mass spectrometry. The relevance of chemistry to assessing and solving environmental problems is highlighted for students when they perform mass spectroscopy experiments.

Lavoisier showed that water was formed by chemical reaction between hydrogen and oxygen. In Lavoisier's "Traite Elementaire" of 1789, he states that the reaction to form water requires exactly two volumes of hydrogen gas to react completely with one volume of oxygen gas. This was 20 years before Gay-Lussac studied the reactions between different…

Discusses predicting common oxidation numbers, uncommon oxidation numbers, hydrogen-phosphorus bonds and other examples. (PVD)

Presents preliminary results from a survey taken by the American Chemical Society (ACS) Committee on Professional Training (CPT) to determine the current practices among 155 Ph.D. programs in chemistry. (DKM)

Provides background information for teachers on the atomic density of the elements as pure crystals. Atomic density is defined as the reciprocal of the atomic volume. Includes atomic-density diagrams which were prepared using the atomic-volume values given by Singman, supplemented by additional values for some allotropes. (JN)

The entropy change for a reaction in aqueous solution can be evaluated as a combination of entropy factors. Valuable insight or understanding can be obtained from a detailed examination of these factors. Several entropy effects of inorganic chemical reactions are discussed as examples. (Author/JN)

Discusses: (1) characteristic initial velocity behavior (considering the five-step reaction sequence for rapid equilibrium-order bisubstrate mechanisms); (2) dead-end inhibition; (3) inhibition by single products; and (4) an activator as a leading reactant. (JN)

Examines energy interconversions in photosynthesis, limiting the discussion to areas pertinent to chemistry (particularly the energetics of the light reactions). Topic areas considered include bioenergetics, photochemistry, conversion of light energy into electrical potential energy, the chemiosmotic hypothesis, and others. (JN)

The 17 rare earth elements account for one-fifth of the 83 naturally occurring elements and collectively rank as the 22nd most abundant "element." Properties of these elements (including their chemical similarity), their extraction from the earth, and their uses are discussed. (JN)

Shows that the rules of thumb for propagating significant figures through arithmetic calculations frequently yield misleading results. Also describes two procedures for performing this propagation more reliably than the rules of thumb. However, both require considerably more calculational effort than do the rules. (JN)

It is not conceivable that in a mixture or compound a component may exist in a negative ratio. Traditionally, therefore, a negative value could not be plotted on triangular coordinates. However, negative values are explicitly allowed, and the results extend the use of triangular coordinates as shown in this article. (JN)

The method of Clarke and Glew is broadly applicable to studies of the temperature dependence of equilibrium constant measurements. The method is described and examples of its use in comparing calorimetric results and temperature dependent gas solubility studies are provided. (JN)

Provides a comprehensive overview of the 19 essential trace elements, examining: the concept of essentiality; evolution of these elements; possible future essential elements; the lanthanides and actinides; how essential trace elements work; the metalloenzymes; the nonmetals; iodine and the thyroid hormones; and antagonism among these elements. (JN)

Discusses the role of zinc in various enzymes concerned with hydration, hydrolysis, and redox reactions. The binding of zinc to protein residues, properties of noncatalytic zinc(II) and catalytic zinc, and the reactions catalyzed by zinc are among the topics considered. (JN)

Provides an overview on biological electron-transfer reactions, summarizing what is known about how distance, spatial organization, medium, and other factors affect electron transfer. Experimental approaches, including studies of bimolecular electron transfer reactions (electrostatic effects and precursor complexes), are considered. (JN)