Discusses the fact that although most historians of science attribute the formulation of the law of conservation of matter in chemical reactions to Antoine Lavoisier at the end of the eighteenth century, several earlier researchers had already assumed this law in their work. These researchers include Joseph Black, Henry Cavendish, M. V. Lomonosov,…

Indicates that the concept of definite proportions or constant composition should be introduced with qualification. Presents arguments against the Law of Definite Proportions and cites examples in the areas of solid solutions, compounds of the transition and inner transition elements, and in some compounds of the representative elements. (GS)

Describes bonding properties that account for the difference in toxicity between hydrogen cyanide and carbon monoxide. Uses the concepts of intermolecular and intramolecular forces in explaining the operation of pressure sensitive adhesives. Gives a definition of a cubic crystal class. (GS)

Presents questions from readers and answers to their questions. Topics in this article include population growth, corrosion in fuel lines, and effect of cooling on seeds and sperm. (RH)

Summarizes current status of our knowledge about acid-base interactions, including Lewis considerations, experimental design, data about donor-acceptor systems, common misconceptions, and hard-soft acid-base model. Indicates that there is the possibility of developing unifying concepts for chemical reactions of inorganic compounds. (CC)

Presents two demonstrations; one on Boyle's Law, to illustrate the gas law and serve as a challenging problem for the students; the other is a modified Color Blind Traffic Light demonstration in which the oscillating reactions were speeded up. (GA)

Provides an application of a direct group theory method to the determination of the number and symmetry of M-C-O groups. The method is explained and three illustrative examples are given. (MR)

Three demonstrations are described: paramagnetic properties of Fe(11) and Fe(111), the preparation of polyurethane foam: a lecture demonstration and the electrolysis of water-fuel cell reactions. A small discussion of the concepts demonstrated is included in each demonstration's description. (MR)

An experiment is described which uses lead sulfide to illustrate the concept of definite proportions as well as the union of atoms to form compounds. This experiment has been successfully used with ninth graders. The advantages of this experimental procedure over available alternatives are listed. (MR)

A laboratory experiment is described which illustrates such concepts as resonance, inductive, steric, and solvation effects in a beginning organic chemistry course. This experiment is designed to encourage students to predict results and interpret their findings. (MR)

Discusses seven-coordinate complexes of the first-row transition metals. (SL)

Defines the rate-controlling step in contrast to the terms rate determining and rate limiting. Discusses the usefulness of this concept in describing kinetic isotope effects, consecutive reactions, chain reactions, and enzyme-catalyzed reactions. (CW)

Describes a demonstration procedure using controlled reduction potentials to predict observed color changes which are then experimentally verified. Demonstrates the usefulness of this procedure in helping students understand LeChatelier's principle and the solubilit rule "like dissolves like." (CW)

Discusses some of the drawbacks of using a demonstration of the electrolysis of water to illustrate the interconversion between electrical and chemical energy. Illustrates a simple apparatus allowing demonstration of this concept while overcoming these drawbacks. (CW)

Listed are ways to demonstrate physical and chemical properties of matter and to show electrolysis using an overhead projector. (RH)