This article describes engaging students in two simple observations to address the concepts of changes of states, heat, temperature, and molecular potential and kinetic energy. It also discusses how these concepts can enable students to further explore and understand interesting and significant phenomena and research in multiple areas of science.…

Shows how the structure-energy principle can be presented in organic chemistry (without having to resort to quantum mechanics) by use of Benson's Additive Rules. Examples of the application to several major classes of organic compounds are given.

Presents procedures for obtaining and examples of delta plots (a way of illustrating electron density changes associated with electronic excitation). These plots are pedagogically useful for visualizing simple and complex transitions and provide a way of "seeing" the origin of highest occupied molecular orbital (HOMO)-dictated carbonyl…

Presents a new view of the electronic structure of pi systems that unifies molecular orbital and valence bond theories. Describes construction of electronic structure diagrams (central to this new view) which demonstrate how configuration interaction can improve qualitative predictions made from simple Huckel theory. (JN)

Pi-CI theory is a simple, semi-empirical procedure which (like Huckel theory) treats pi and pseudo-pi orbitals; in addition, electron repulsion is explicitly included and molecular configurations are mixed. Results obtained from application of pi-CI to ethylene are superior to either the Huckel molecular orbital or valence bond theories. (JN)

Discusses the nature of experimental resonance energy, explaining how its magnitude depends upon choice of reference molecules from which bond energies are derived. Also explains how it can be evaluated more simply, without recourse to bond energies, as enthalpy change for a reaction predetermined by choice of reference molecules. (JN)

The RKR method for determining accurate potential energy curves is described. Advantages of using the method (compared to Morse procedure) and a TRS-80 computer program which calculates the classical turning points by an RKR method are also described. The computer program is available from the author upon request. (Author/JN)

Discussed is the fundamental role that the favorable free energy of binding of the rate-determining transition state plays in catalysis. The principle that all of the catalytic factors discussed are realized by the use of this binding energy is reviewed. (CW)

Discusses the energy levels of 3d and 4s electrons. (SL)

Molecular mechanics is a nonquantum mechanical method for solving problems concerning molecular geometries and energy. Methodology based on: the principle of combining potential energy functions of all structural features of a particular molecule into a total force field; derivation of basic equations; and use of available computer programs is…

Details a procedure for accurately calculating the quantum mechanical energies of hydrocarbons using the perturbational molecular orbital (PMO) method, which does not require the use of a computer. (BT)

Discusses the role of semiclassical theory in chemical physics both as a computational method and conceptual framework for interpreting quantum mechanical experiments and calculations. Topics covered include energy wells and eigenvalues, scattering, statistical mechanics and electronically nonadiabiatic processes. (JM)

The application of molecular mechanics (a nonquantum mechanical method for solving problems concerning molecular geometries) to calculate force fields for n-butane and cyclohexane is discussed. Implications regarding the stable conformations of the example molecules are also discussed. (Author/SK)

Presented are forms of harmonic oscillator attraction and Coulomb wave functions which can be explicitly constructed and which lead to numerical results for the energy eigenvalues and eigenfunctions of the atomic system. The Schrodinger equation and its solution and specific cases of muonic atoms illustrating numerical calculations are included.…

It is shown that exact pseudopotentials for excited states of hydrogen atoms can be derived. A very simple, novel application of pseudopotential method which displays vividly some of its limitations is presented. (Author/GA)