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The importance of kinetic metastability is illustrated in detail using several common household products and recommendations are made for how this important and widespread, but often neglected, phenomenon can be more effectively presented in the introductory chemistry textbook.

This historical review traces the origins of the Kimball free-cloud model of the chemical bond, otherwise known as the charge-cloud or tangent-sphere model, and the central role it played in attempts to reform the introductory chemical curriculum at both the high school and college levels in the 1960s. It also critically evaluates the limitations of the model, its current implicit role in the teaching of VSEPR theory, and its pedagogical implications, as well as providing a resource paper for those chemical educators interested in exploring its present-day applications.

Argues that the failure to identify concepts and definitions with their corresponding levels of discourse has resulted in the propagation of historically outdated definitions and vocabulary in chemistry textbooks. Provides several examples of the problem from textbooks. Contains 36 references. (DDR)

Makes reference to a logic table introduced in the first keynote address of a series of three that focus on the history of chemistry and its application to teaching. Contains 42 references. (DDR)

This paper calls attention to the early work of the American chemists Worth Rodebush and Groves Cartledge, and their anticipations of a quantitative electronegativity scale, which predate the classic 1932 paper of Linus Pauling by several years. (Contains 2 figures.)

A survey of introductory textbooks shows that many authors fail to connect explicitly their discussions of empirical versus molecular formulas with their latter discussions of the composition and structure of nonmolecular solids. A study proposes that some method, such as the use of quotation marks, be adopted to differentiate unambiguously empirical formulas from molecular formulas, and that the terms "empirical" and "molecular" be replaced by the more descriptive terms "relative" and "absolute".

Discusses major events leading to the development of the octet rule. Three conclusions based on the work of Mendeleev, Abegg, Thompson, Kossel, Lewis, and Langmuir are considered as is the debate over the rule's validity. (JN)

In response to a reader query, the article traces the origins of our current nomenclature and symbolism for isotopes. (Contains 2 tables.)

In response to a reader query, this article traces the history of fusible alloys, including Newton's metal, D'Arcet's metal, Rose's metal, Onion's fusible alloy, and Wood's metal. (Contains 1 table and 1 figure.)

In response to a reader query, this article traces the origins of the ionic-radius ratio rules and their incorrect attribution to Linus Pauling in the chemical literature and to Victor Goldschmidt in the geochemical literature. In actual fact, the ionic-radius ratio rules were first proposed within the context of the coordination chemistry literature by the Austrian chemist, Gustav F. Huttig, in a brief note published in 1920 in which he reported the R[subscript -]/R[subscript +] ratio for possible geometries corresponding to coordination numbers of 2, 3, 4, 5, 6, 8, 12, and 20. Two years later the German chemist, Alfred Magnus, gave a more detailed treatment explicitly linked to Walther Kossel's recently proposed electrostatic screening theory of complex ion formation and also included values for various alternative coordination geometries, such as square planar versus tetrahedral and hexagonal planar versus octahedral. In 1923, Huttig's original results were cited by Max Lembert in a discussion of the structures of complex hydrates, and the following year they were incorporated into the second edition of Rudolf Weinland's textbook, "Einfuhrung in die Chemie der Komplexverbindungen." In a series of papers published in 1925 by Rudolf Straubel and Huttig, the rules were further linked to the concept of packing efficiency.

The theory of s, p, d and f dealing with the line spectra of the alkali metals during the period 1881 based on analogies with the harmonic ratios of sound is described. Friedrich Hund followed Bohr's practice of labelling the various shells and subshells by replacing the secondary quantum number with the series notations (s, p, d, and f), which began to slowly leak into the chemical literature by 1930 and reigned supreme ever since.

The debate related to origin of the term "hypervalent" that was first introduced by Jeremy Musher in 1969 to describe compounds and complex ions of the heavier main-block elements in which the use of traditional Lewis 2c-2e covalent bonds requires the additional assumption of "octer expansion" for the central atom is presented. The traditional Lewis 2c-2e model of covalent bonding is still important in introductory chemistry textbooks, because they are a necessary component of the highly successful VSEPR model for the prediction of molecular geometries.

The history behind the association of Avogadro's name related to the hypothesis that equal volumes of gases at constant temperature and pressure contain equal numbers of molecules is explored. The findings suggest that the index entry "Avogadro's Number" did not become common in American college texts until the 1930s and was rare in American high school texts before the 1950s.

A question about the historical origin of equal sign and double arrow symbolism in balanced chemical equation is raised. The study shows that Marshall proposed the symbolism in 1902, which includes the use of currently favored double barb for equilibrium reactions.

Campbell's rule for estimating entropy changes is discussed in relation to an earlier article by Norman Craig, where it was proposed that the approximate value of the entropy of reaction was related to net moles of gas consumed or generated. It was seen that the average for Campbell's data set was lower than that for Craig's data set and discrepancies were present in certain aspects.

German Chemist, August Wilhelm Hofmann first introduced the term "molar" (from the Latin moles, meaning "a large mass") into chemistry, around 1865. The particular use of the term molar gained currency in the physics literature, where it was in common use at least through the 1940s.

The origin of the "proof" system for measuring the ethanol content of alcoholic beverages is presented. The proof system was originally established for purposes of taxing liquors according to their alcohol content and is different in different countries.

Edward Frankland and Norman Lockyer researched upon a gaseous spectra in relation to the physical constitution of the sun and named it as "helium" (from Greek "helios" meaning "sun"). Since Lockyer apparently never formally proposed the name in print, it is not known why he chose to use a metallic end "ium".

Described is a method of utilizing the standard ball and stick models, used in demonstrating molecular structure, for building two electron bonding components. Included is the construction of several molecules with word and picture descriptions. (Author/DS)