Chemical Bonding Clarified Through Quantum Mechanics

Quantum mechanics, including quantum field theory, is a fundamental theory in physics which describes nature at the smallest - including atomic and subatomic - scales. Very simply stated: Quantum Mechanics is concerned with the as yet unsolved question: "What is Light?" Is light a particle, or is it a wave? The title logo to this book is made so that you can see through it. George Claude Pimentel (May 2, 1922 - June 18, 1989) was the inventor of the chemical laser. He also developed the technique of matrix isolation in low-temperature chemistry. In theoretical chemistry, he proposed the three-center four-electron bond which is now accepted as the best simple model of hypervalent molecules. In the late 1960s, Pimentel led the University of California team that designed the infrared spectrometer for the Mars Mariner 6 and 7 missions that analyzed the surface and atmosphere of Mars. An alumnus of University of California, Los Angeles (B.S. 1943) and University of California, Berkeley (Ph.D. 1949), Pimentel began teaching at Berkeley in 1949, where he remained until his death in 1989.

The concept of a chemical bond evolved from a variety of experimental observations. It became useful to understand, at times even predict, the molecular structure, reactivity and mechanism of chemical reactions. Every aspect of the concept of bonding received a quantitative interpretation from the advent of quantum mechanics and its application to chemistry.In Lectures on Chemical Bonding and Quantum Chemistry the reader will find a comprehensive discourse on the basic interpretation of the chemical bond as well as current understanding in terms of a 'dancing' molecule that not only travels, rotates and pulsates around an equilibrium molecular structure, but also interacts and collides with other molecules, thereby transferring linear and angular momentum characteristics and adjusting total energies. One will also find a thorough survey of quantum mechanical methodologies for calculation of molecular characteristics in specific states and their changes under spectroscopic transitions, tunneling, electron and proton transfer phenomena, and so on. Guides to more advanced levels of theory are also provided.

The present text is a rational analysis of the concept of the chemical bond by means of the principles of wave mechanics. The discussion of the material has been arranged so as to render its main content comprehensible for readers who may not have had pre"ious training in quantum mechanics. The text comprises three major parts. It begins with an exposition of the fundamental ideas. In this section the principles are reviewed from which de Broglie developed his mechanics; this allows the book to be read by chemistry majors and freshmen alike. However, we believe that it may also be of interest to university-and college teachers who must include certain aspects of quantum chemistry into their courses while being insufficiently familiar with the subject. It may even be of interest to science teachers in secondary schools. Finally, having been a witness to the evolution of these notions for over a quarter of a century, we present certain concepts from a particular point of view which might prove attractive to chemists of all kinds, perhaps even quantum chemists. The second, more technical part summarizes the methods of constructing wave functions that describe the electrons in molecules. This section can only be fully appreciated by those readers who are familiar with some aspects of the algorithms used in quantum mechanics.

This book is a presentation of a qualitative theory of chemical bonding, stressing the physical processes which occur on bond formation. It differs from most (if not all) other books in that it does not seek to “rationalise” the phenomena of bonding by a series of mnemonic rules. A principal feature is a unified and consistent treatment across all types of bonding in organic, inorganic, and physical chemistry. Each chapter has an Assignment Section containing “problems” which might be usefully attempted to improve the understanding of the new material in that chapter. The new edition has had several appendices added which give support to concepts which, if included in the main text, would have hindered the main thrust of the presentation. These new appendices are an attempt to clarify oversights and errors which have been tacitly ignored and which have now become part of the conventional wisdom.

Principles of Quantum Chemistry focuses on the application of quantum mechanics in physical models and experiments of chemical systems. This book describes chemical bonding and its two specific problems — bonding in complexes and in conjugated organic molecules. The very basic theory of spectroscopy is also considered. Other topics include the early development of quantum theory; particle-in-a-box; general formulation of the theory of quantum mechanics; and treatment of angular momentum in quantum mechanics. The examples of solutions of Schroedinger equations; approximation methods in quantum chemistry; symmetry in chemistry; and molecular-orbital theory are also covered. This publication is recommended for students taking undergraduate and graduate courses in quantum chemistry.

Providing the quantum-mechanical foundations of chemical bonding, this unique textbook emphasizes key concepts such as superposition, degeneracy of states and the role of the electron spin. An initial, concise and compact presentation of the rudiments of quantum mechanics enables readers to progress through the book with a firm grounding. Experimental examples are included to illustrate how the abstract concepts are manifest in real systems.

This book explores the way in which quantum theory has become central to our understanding of the behaviour of atoms and molecules. It looks at the way in which this underlies so many of the experimental measurements we make, how we interpret those experiments and the language which we use to describe our results. It attempts to provide an account of the quantum theory and some of its applications to chemistry. This book is for researchers working on experimental aspects of chemistry and the allied sciences at all levels, from advanced undergraduates to experienced research project leaders, wishing to improve, by self-study or in small research-orientated groups, their understanding of the ways in which quantum mechanics can be applied to their problems. The book also aims to provide useful background material for teachers of quantum mechanics courses and their students.