Download or read book A Chemist s Guide to Valence Bond Theory written by Sason S. Shaik and published by John Wiley & Sons. This book was released on 2007-12-04 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: This reference on current VB theory and applications presents a practical system that can be applied to a variety of chemical problems in a uniform manner. After explaining basic VB theory, it discusses VB applications to bonding problems, aromaticity and antiaromaticity, the dioxygen molecule, polyradicals, excited states, organic reactions, inorganic/organometallic reactions, photochemical reactions, and catalytic reactions. With a guide for performing VB calculations, exercises and answers, and numerous solved problems, this is the premier reference for practitioners and upper-level students.
Download or read book Valence Bond Theory written by David Cooper and published by Elsevier. This book was released on 2002-06-05 with total page 837 pages. Available in PDF, EPUB and Kindle. Book excerpt: Valence bond (VB) theory, which builds the descriptions of molecules from those of its constituent parts, provided the first successful quantum mechanical treatments of chemical bonding. Its language and concepts permeate much of chemistry, at all levels. Various modern formulations of VB theory represent serious tools for quantum chemical studies of molecular electronic structure and reactivity. In physics, there is much VB-based work (particularly in semi-empirical form) on larger systems. Importance of TopicThe last decade has seen significant advances in methodology and a vast increase in the range of applications, with many new researchers entering the field.Why This TitleValence Bond Theory succeeds in presenting a comprehensive selection of contributions from leading valence bond (VB) theory researchers throughout the world. It focuses on the vast increase in the range of applications of methodology based on VB theory during the last decade and especially emphasizes recent advances.
Download or read book Mixed Valence Compounds written by D.B. Brown and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 517 pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been a decade since two seminal reviews demonstrated that mixed-valence compounds share many unique and fascinating features. The insight pro vided by those early works has promoted a great deal of both experimental and theoretical study. As a result of extensive efforts, our understanding of the bonding and properties of mixed-valence compounds has advanced substantially. There has been no compre hensive treatment of mixed-valence compounds since 1967, and the meeting convened at Oxford in September, 1979, provided a unique opportunity to examine the subject and its many ramifications. Mixed-valence compounds play an important role in many fields. Although the major impact of the subject has been in chemistry, its importance has become increasingly clear in solid state physics, geology, and biology. Extensive interest and effort in the field of molecular metals has demonstrated that mixed-valency is a prerequisite for high elec trical conductivity. The intense colors of many minerals have been shown to be due to mixed-valency, and the electron-transfer properties of certain mixed-valence metalloproteins are important in biological processes. Experts from all of these areas participated in this meeting, and the truly interdisciplinary nature of the subject made it a unique learning experience for all in attendance.
Download or read book Valency and Molecular Structure written by E. Cartmell and published by Butterworth-Heinemann. This book was released on 2013-10-22 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Valency and Molecular Structure, Fourth Edition provides a comprehensive historical background and experimental foundations of theories and methods relating to valency and molecular structures. In this edition, the chapter on Bohr theory has been removed while some sections, such as structures of crystalline solids, have been expanded. Details of structures have also been revised and extended using the best available values for bond lengths and bond angles. Recent developments are mostly noted in the chapter on complex compounds, while a new chapter has been added to serve as an introduction to the spectroscopy of complex compounds. Other topics include the experimental foundation of the quantum theory; molecular-orbital method; ionic, hydrogen, and metallic bonds; structures of some simple inorganic compounds; and electronic spectra of transition-metal complexes. This publication is a useful reference for undergraduate students majoring in chemistry and other affiliated science subjects.
Download or read book Valence Theory written by John Norman Murrell and published by John Wiley & Sons. This book was released on 1970 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: THE FOUNDATIONS OF ATOMIC THEORY; THE ELECTRON IN A CONSTANT POTENTIAL; THE HYDROGEN ATOM; MANY-ELECTRON ATOMS AND THE PERIODIC TABLE; BASIC PRINCIPLES OF THE THEORY OF VALENCE; THE MATHEMATICAL FOUNDATIONS OF QUANTUM MECHANICS; THE WARE FUNCTIONS OF MANY-ELECTRON SYSTEMS; SYMMETRY; ANGULAR MOMENTUM AND ATOMIC ENERGY LEVELS; MOLECULAR-ORBITALTHEORY: ITS APPLICATIONS TO THE ELECTRONIC STRUCTURE OF DIATOMIC MOLECULES; THE VALENCE BOND THEORY ITS APPLICATIONS TO DIATOMIC MOLECULES; THE BONDING IN POLYATOMIC MOLECULES; LIGAND-FIELD THEORY; THE ELECTRONIC STRUCTURE OF OLECTRON-DEFICIENT MOLECULES; ELECTRON THEORY OF ORGANIC MOLECULES; THE ELECTRONIC THEORY OF ORGANIC CHEMISTRY; REACTIONS AND RELATIBE REACTIVITY IN ORGANIC CHEMISTRY; WEAK CHEMICAL BONDS; HINTS TOPROBLEMS.
Download or read book Valence and the Structure of Atoms and Molecules written by Gilbert Newton Lewis and published by . This book was released on 1923 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Performance Politics and the British Voter written by Harold D. Clarke and published by Cambridge University Press. This book was released on 2009-07-23 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shows that judgment of party competence is at the heart of electoral choice in contemporary Britain.
Download or read book The Electronic Theory of Valency written by Nevil Vincent Sidgwick and published by . This book was released on 1927 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Valence Instabilities and Related Narrow Band Phenomena written by R. Parks and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: Those well-intending workers, especially theorists, who have viewed hungrily the mixed valence problem, but have not yet made the bold leap, might be comforted to learn that the Rochester conference left the virginal state of that problem essentially intact. That is not to say that the event was prosaic. Indeed, the conferees exhibited a level of effervescence appropriate to the freshness and challenge of the problem at hand. If the meeting failed to solve major questions, it at least established several guidelines. One is that future experimental efforts, at least on a short time scale, might be spent most profitably on those substances which exhibit consistent, and hence probably intrinsic, behavior from laboratory to laboratory. A recurring message, not always subtle, to the·theorists was that piecemeal approaches to the mixed valence problem, characteristic of much of the work to date, are of limited usefulness. For at the core of the problem one has a melange of boot-strapping interac tions which must be sorted out and dealt with properly. Para phrasing Phil Anderson (see Epilogue), the mixed valence problem is in the same category of problems which are failing to be done in field theory these days.
Download or read book Qualitative Valence Bond Descriptions of Electron Rich Molecules Pauling 3 Electron Bonds and Increased Valence Theory written by R. D. Harcourt and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides qualitative molecular orbital and valence-bond descriptions of the electronic structures for electron-rich molecules, with strong emphasis given to the valence-bond approach. Electron-rich molecules form an extremely large class of molecules, and the results of quantum mechanical studies from different laboratories indicate that qualitative valence-bond descriptions for many of these molecules are incomplete in so far as they usually omit "long-bond" Lewis structures from elementary descriptions of bonding. For example, the usual representation for the electronic structure of the ground-state for 03 involves resonance between the (+1 o and Until standard Lewis structures ~ ~ (-I . b:'" ~d· . . . . , recently, any contribution to resonance of the "long-bond" (or spin-paired o •• / •• ,. . has been largely ignored. diradica~ Lewis structure However, it :0 . 0. . e-. . . . . ______ " has now been calculated to be a very important structure. For the ground-states of numerous other systems, calculations also indicate that "long-bond" structures are more important than is usually supposed, and therefore they should frequently be included in qualitative valence-bond descriptions of electronic structure. The book describes how this may be done, and some of the resulting consequences for the interpretation of the electronic structure, bond properties and reactivities of various electron-rich molecules. When appropriate, molecular orbital and valence bond descriptions of bonding are compared, and relationships that exist between them are derived.
Download or read book Molecules and the Chemical Bond written by Henry A. Bent and published by Trafford Publishing. This book was released on 2013-09-30 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: MOLECULES and the Chemical Bond is about understanding Schrdingers equation, for chemical systems. In his famous Lectures on Physics, Richard Feynman quotes Paul Dirac on what it means to understand an equation. I understand what an equation means, said Dirac, if I have a way of figuring out the characteristics of its solutions without actually solving it. That hits the nail on the head! Its precisely what Conceptual Valence Bond Theory does for Schrdingers equation. A physical understanding of an equation, adds Feynman, is a completely unmathematical, imprecise, and inexact thing, but absolutely necessary for a physicist. It unfolds in MCB in two stages, described by Newton as a stage of Analysis (a union of observations and inductions) and a stage of Synthesis (use of inductions, accepted as first principles, to explain observations). The books chief vehicle for creating an intuitive understanding of solutions of Schrdingers equation is the worlds largest and to the authors knowledge, virtually only library of line drawings of exclusive orbital models of chemical species electron density profiles. By focussing attention on fundamental physical principles and by avoiding use of atomic orbitals and, thereby, mathematical complexities associated with Schrdingers equation (the only source of atomic orbitals), the books essays provide a scientifically sound, student-friendly introduction to modern valence theory. Repetition of fundamental ideas, here and there, is intended to make individual essays understandable and interesting, each by itself, so that readers may examine them in any order, in leisurely walks, so to speak, in the big garden that is valence theory, picking bouquets to their liking.
Download or read book Valence Bond Methods written by Gordon A. Gallup and published by Cambridge University Press. This book was released on 2002-07-11 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
Download or read book Introduction to Valence Theory written by Jean Worrall and published by . This book was released on 1969 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computing Attitude and Affect in Text Theory and Applications written by James G. Shanahan and published by Springer Science & Business Media. This book was released on 2006-01-17 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Human Language Technology (HLT) and Natural Language Processing (NLP) systems have typically focused on the “factual” aspect of content analysis. Other aspects, including pragmatics, opinion, and style, have received much less attention. However, to achieve an adequate understanding of a text, these aspects cannot be ignored. The chapters in this book address the aspect of subjective opinion, which includes identifying different points of view, identifying different emotive dimensions, and classifying text by opinion. Various conceptual models and computational methods are presented. The models explored in this book include the following: distinguishing attitudes from simple factual assertions; distinguishing between the author’s reports from reports of other people’s opinions; and distinguishing between explicitly and implicitly stated attitudes. In addition, many applications are described that promise to benefit from the ability to understand attitudes and affect, including indexing and retrieval of documents by opinion; automatic question answering about opinions; analysis of sentiment in the media and in discussion groups about consumer products, political issues, etc. ; brand and reputation management; discovering and predicting consumer and voting trends; analyzing client discourse in therapy and counseling; determining relations between scientific texts by finding reasons for citations; generating more appropriate texts and making agents more believable; and creating writers’ aids. The studies reported here are carried out on different languages such as English, French, Japanese, and Portuguese. Difficult challenges remain, however. It can be argued that analyzing attitude and affect in text is an “NLP”-complete problem.
Download or read book Atomic Theories written by F. H. Loring and published by . This book was released on 1923 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unified Valence Bond Theory of Electronic Structure written by N. D. Epiotis and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unified Valence Bond Theory of Electronic Structure written by N. D. Epiotis and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: The bond diagrammatic representation of molecules is the foundation of MOVB theory. To a certain extent, this kind of representation is analogous to the one on which "resonance theory" is based and this fact can be projected by a comparison of the various ways in which MOVB theory depicts a species made up of three core and two ligand MO's which define two subsystems containing a total of six electrons and the ways in which "resonance theory" (i. e. , qualitative VB theory) depicts a six-electron-six-AO species such as the pi system of CH =CH-CH=CH-CH=O. The 2 different pictorial representations are shown in Scheme 1 so that the analogies are made evident. First of all, the total MOVB diagrammatic representation of the 6/5 species is obtained by a linear combination of three complete bond diagrams, as in Al, which describe the optimal linear combination of!l! MOVB Configuration Wavefunctions (CW's). By the same token, a total VB diagrammatic representation of the 6/6 species can be obtained by writing a "dot structure", as in Bl, and taking this to mean the optimal linear combination of all VB CW's. Next, we can approxi mate the MOVB wavefunction of the 6/5 species by one complete (or detailed) bond dia gram" (A2). No simple VB representation analogy can be given in this case. Alterna tively, we can approximate the MOVB wavefunction by a linear combination of compact bond diagrams, as in A3, in the way described before.
