Discusses the brief history of microcomputers, offering some predictions about hardware trends. Gives explicit criteria for judging a computer language and discusses different programing languages in terms of what has been used in the past, and why, and what might be appropriate for the future. (JN)

There are two conflicting views about the mechanism of 1,3-dipolar cycloadditions to multibonds. To reconcile these viewpoints a concerted, spin-paired, diradical mechanism, based on valence bond theory, is proposed. Each of these three mechanisms is discussed. (JN)

Traces the development of the Arrhenius equation from its beginning, examining the more important alternate proposals and the work that supported them. Aside from its historical interest, this examination affords insight into how scientific progress is made. (JN)

Discusses: (1) geologists and the history of geology; (2) American historians and the history of geology; (3) history of geology in the 1980s; (4) sources for the history of geology (bibliographies, dictionaries, encyclopedias, handbooks, periodicals, public/official histories, compilations, and books); (5) research opportunities; and (6) other…

Examines the history of biology in the United States by considering: (1) general trends about the nature of American biology; (2) sources of information; (3) biographies; (4) biological institutions; and (5) disciplinary studies. Indicates that the field is dominated by internalists who focus on particular persons and topics. (JN)

Argues that two problems (the mole concept and mathematical reasoning) can be reduced by carefully distinguishing betwen quantities and numbers, by replacing mole as a unit for stoichiometric calculation with a number of particles as the unit for calculation, and by introducing students to the language of quantity calculus. (JN)

Discusses misconceptions (in several thermodynamics statements) that seem to be particularly common among students who have finished a one-semester, junior-level course in chemical thermodynamics. When presented as true/false questions, these statements are usually judged true, although each requires at least one more condition to be satisfied.…

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)

Presents a laboratory exercise designed to introduce graphical extrapolation. Major advantages of the method are in its simplicity and speed. The only measuring devices are a centimeter ruler and a micrometer caliper to check wall thickness. (JN)

The concept of an ideal solution is ordinarily introduced in freshman chemistry by means of Raoult's Law, which states that the vapor pressure of a volatile component of a solution is proportional to its mole fraction. The relationship of this law to molecular size is discussed. (JN)

Outlines procedures for producing both 35-mm and overhead transparencies using a photocopier with a reducing capability. (JN)

Background information, procedures used, and typical results obtained are provided for an experiment involving the separation of chlorophyll a and chlorophyll b from their diastereomers. Reasons why the experiment can be easily integrated into most laboratory curricula where high-performance liquid chromatography capabilities exist are given. (JN)

Provides a question (with the acceptable answer) designed to test students' ability to apply, and extend, the concept of thermodynamic work discussed in the classroom. The question was originally designed as a part of a take-home examination. (JN)

Determined: (1) whether students thought of magnetic poles as exerting forces directly on electric charges and (2) the specific strategies students used to make predictions about the forces acting on electric charges in two problem situations. Implications for instruction are considered. (JN)

Presents a condensed version of textbook account of cosmological theory and principles. Topics discussed include quasars, general and special relativity, relativistic cosmology, and the curvature of spacetime. Some philosophical assumptions necessary to the theory are also discussed. (JM)