Pauling


Pauling L and Wilson E B 1935 Introduction to Quantum Mechanics (New York Dover)  [c.52]

Figure A2.3.17 Theoretical (HNC) calculations of the osmotic coefficients for the square well model of an electrolyte compared with experimental data for aqueous solutions at 25°C. The parameters for this model are a = r (Pauling)+ r (Pauling), d = d = 0 and d as indicated in the figure. Figure A2.3.17 Theoretical (HNC) calculations of the osmotic coefficients for the square well model of an electrolyte compared with experimental data for aqueous solutions at 25°C. The parameters for this model are a = r (Pauling)+ r (Pauling), d = d = 0 and d as indicated in the figure.
Pauling L and Wilson E B 1935 Introduction to Quantum Mechanics (New York McGraw-Hill) pp 294-314  [c.1147]

These effects are clearly seen for saturated molecules in table BTl 1.1. which correlates the H and C NMR chemical shifts of a series of compounds X-CH with the approximate Pauling electronegativities of X. Both and increase with X as predicted, although the sequence is slightly disordered by additional, relativistic effects at the C atoms, when X is a heavy atom such as I. The correlations of shift with changes in the local electric charge and, hence, with orbital radius, are also seen for an aromatic system in figure B1.11.6. Here the hydrogen and carbon chemical shifts in phenol, quoted relative to benzene, correlate fairly well both with each other and also with the charge distribution deduced by other means.  [c.1446]

The exchange integrals K j contain terms such as (i,i + l g i+ l,i) + 25i i+[ i h i+i) [138]. The second term, representing the attractive interaction between two nuclei and the electronic overlap charge between them, is the dominant one and completely outweighs the first repulsive term. therefore has the same sign as the Coulomb integral Q. (For a similar derivation, see [139].) In Eq. (A.7), //ab.cl is the cross-term obtained by classic VB theory [140], in which only contributions from electron pairwise transposition permutations were considered. Bonding in these systems is due mainly to the exchange integrals Ki i+i between orbitals in the same cycle [138]. Pauling [140] showed that the most important contributions are due to neighboring orbitals, justifying the neglect of the smaller terms in Eq. (A.7).  [c.393]

L. Pauling, The Nature of the Chemical Bond, Cornell University Press, Ithaca, N.Y., 1940.  [c.394]

L. Pauling, J. Chem. Phys. 1, 280 (1933).  [c.398]

Pauling and others have attempted to define an electronegativity scale by which the inequality of sharing might be assessed. Some of Pauling s electronegativity values are shown in Table 2.11. The greater the differences in the electronegativities of the two elements joined by a covalent bond, the less equally the electrons are  [c.49]

SOME ELECTRONEGATIVITY VALUES (PAULING)  [c.50]

Pauling s electronegativity values are derived from the differences between pure covalent and actual bond energies. Another simple measure of electronegativity is the sum of the ionisation energy and electron affinity. I + E The more electronegative elements have high values of / -E , Consider the alternative ionic forms of the diatomic species AB . i.e. A B or A B. To form the first in the gas phase requires an energy 1 - Eg, to form the second requires an energy Ig - Whichever energy is the lesser will indicate the direction of electron transfer if A is more electronegative than B then we require that A B is favoured and thus that 1/ Ig > Ig - a or 1/ + > Ig + Eg and on this basis the order of values of  [c.50]

Element Atomic number Outer electrons Atomic radius (nm) m.p. (K) h.p. (K) 1st ionisation energy (kj Electro- negativity (Pauling)  [c.206]

Historical Note. It is interesting to note (Pauling and Wilson, 1935) that the very first systematic approach to what we now call quantum mechanics was made by Heisenberg, who began to develop his own algebra to describe the frequencies and intensities of spectral transitions. It was soon seen by Born and Jordan that Heisenberg s new algebra is really matrix algebra. Heisenberg s eigenfunctions were later called wave functions by Schroedinger in an independent but equivalent method. Schroedinger s method is now called wave mechanics and is the method most familiar to chemists. Heisenberg s method is called matrix mechanics.  [c.39]

Pauling. L., 1960. The Nature of the Chemical Bond. Cornell Univ. Press, Ithaca, NY.  [c.336]

Pauling, L. and Wilson, E. B., 1935. Introduction to Quantum Mechanics. McGraw-Hill, New York. Reprinted (1963). Dover, New York.  [c.336]

Introduction to Quantum Mechanics, L. Pauling and E. B. Wilson, Dover Publications, Inc., New York, N. Y. (1963)- Pauling and Wilson.  [c.6]

On pages 133-136 of Pauling and Wilson are tabulated the bound-state solutions of this problem for n ranging up to n=6 and 1-values up to 1=5.  [c.562]

Kekule s four-valent carbon was explained later on basis of the atomic concept and the rule of eight valence electrons of the electronic theory of chemistry. From this, G. N. Lewis introduced the electron pair concept and that of covalent shared electron pair bonding (Lewis bond), which Langmuir (Nobel Prize in chemistry, 1932) further developed. It was Linus Pauling (Nobel Prize in chemistry, 1954), and others following him, who subsequently applied the principles of the developing quantum theory to the questions of chemical bonding. I prefer to use chemical bonding instead of chemical bond, because, after all, in a strict sense the chemists beloved electron pairs do not exist. Electrons move individually, and it is only the probability that they are found paired in close proximity that justifies the practical term of covalent electron-pair bonding. Pauling showed that electron pairs occupying properly oriented orbitals (which themselves are the preferred locations, but do not exist otherwise) result in the tetrahedral structure of methane (involving sp hybridization). However, neither Lewis-Langmuir nor Pauling considered that an already shared eleetron pair could further bind an additional atom, not just two.  [c.155]

L. Pauling, General Chemistry 13, Dover, New York (1970).  [c.4]

L. Pauling, E. B. Wilson, Jr., Introduction to Quantum Mechanics With Applications to Chemistry Dover, New York (1963).  [c.17]

Wheland, G. W. Pauling, L. (1935). y. Am. chem. Soc. 57, 2086.  [c.144]

Packer, J. 82, 87, 88, 104, los Parkanyi, C. 212, 213, 220 Parsons, P. G. 207, 2ig Paton, R. P. 186, 187, ig7 Paul, M. A. 86, 89, 93, 106 Pauling, L. 130, 144 Pearsall, H. W. 113, /20 Pearson, D. E. 137, 14s Pearson, R. B. 42, 49 Pearson, R. G. 155, i(>2 Pearson, R. L. 72, 73, 75 Peeling, E. R. 14, jo, 50, 73, 83, ro6, 164-6, igs  [c.235]

Linus Pauling is portrayed on this 1977 Volta stamp The chemical formulas depict the two resonance forms of ben zene and the explosion in the background symbolizes Pauling s efforts to limit the testing of nuclear weapons  [c.3]

Already in 1938, Evans and Warhurst [17] suggested that the Diels-AIder addition reaction of a diene with an olefin proceeds via a concerted mechanism. They pointed out the analogy between the delocalized electrons in the tiansition states for the reaction between butadiene and ethylene and the tt electron system of benzene. They calculated the resonance stabilization of this transition state by the VB method earlier used by Pauling to calculate the resonance energy of benzene. They concluded that the extra aromatic stabilization of this transition state made the concerted route more favorable then a two-step process. In a subsequent paper [18], Evans used the Hilckel MO theory to calculate the transition state energy of the same reaction and some others. These ideas essentially introduce a chemical reacting complex (reactants and products) as a two-state system. Dewar [42] later formulated a general principle for all pericyclic reactions (Evans principle) Thermal pericyclic reactions take place preferentially via aromatic transition states. Aromaticity was defined by the amount of resonance stabilization. Evans principle connects the problem of themial pericyclic reactions with that of aromaticity Any theory of aromaticity is also a theory of pericyclic reactions [43]. Evans approach was more recently used to aid in finding conical intersections [44], (cf. Section Vni).  [c.341]

The space filling model developed by Corey, Pauling, and Koltun is also known as the CPK model, or scale model [197], It shows the relative volume (size) of different elements or of different parts of a molecule (Figure 2-123d). The model is based on spheres that represent the "electron cloud . These atomic spheres can be determined from the van der Waals radii (see Section 2.10.1), which indicate the most stable distance between two atoms (non-bonded nuclei). Since the spheres are all drawn to the same scale, the relative size of the overlapping electron clouds of the atoms becomes evident. The connectivities between atoms, the bonds, are not visualized because they are located beneath the atom spheres and are not visible in a non-transparent display (see Section 2.10). In contrast to other models, the CPK model makes it possible to visualize a first impression of the extent of a molecule.  [c.133]

When a specific value above is n ot hn own, the rule of Pauling (the van der Waals radius is approximately 0.76 A larger than the cova-len t radiiis) is u sed.  [c.213]

The models that most chemists first encounter are molecular models such as the stick models devised by Eheiding or the space filling models of Corey, Pauling and Koltun (commonly referred to as CPK models). These models enable three-dimensional representations of the structures of molecules to be constructed. An important advantage of these models is that they are interactive, enabling the user to pose what if. .. or is it possible to. .. questions. These structural models continue to play an important role both in teaching and in research, but molecular modelling is also concerned with more abstract models, many of which have a distinguished history. An obvious example is quantum mechanics, the foundations of which were laid many years before the first computers were constructed.  [c.21]

Pauling L, R B Corey and H R Bronson 1951. The Structure of Proteins Two Hydrogen-bonded He Configurations of the Polypeptide Chain. Proceedings of the National Academy of Sciences USA y . 211  [c.577]

The hydrogen molecule ion is best set up in confocal elliptical coordinates with the two protons at the foci of the ellipse and one electron moving in their combined potential field. Solution follows in mueh the same way as it did for the hydrogen atom but with considerably more algebraic detail (Pauling and Wilson, 1935 Grivet, 2002). The solution is exact for this system (Hanna, 1981).  [c.171]

The second great advance of twentieth century physics came in the form of quantum theory. Quantum theory deals with probabilities. The great success of quantum mechanics and its wide applications cannot overcome this point. It was because of this that Einstein himself never fully accepted quantum mechanics (his frequently quoted saying was God does not play dice ). Fie attempted for many years to develop a theory combining quantum mechanics and relativity but never succeeded. The effort still goes on for a unified theory, and it may one day succeed. As mentioned the string theory promises to develop a complex mathematical solution with some 11 dimensions, but it is unclear what new physical meaning will derive from it. For chemists the advent of quantum theory also brought new vistas. It was Pauling and subsequently others who introduced into chemistry the concepts of quantum mechanics. Pauling, for example, treated the structure of benzene in terms of what he called resonance (instead of electron exchange used by Heisenberg, Heither, London, and others). He assumed limiting forms to derive the more stable intermediate structure  [c.35]

Concerning taxes, I was told that even the Nobel gold medal could be taxed based on its weight (seemingly the only value tax authorities put on it). I must confess, however, not to have paid duty on it, even after declaring it properly upon our return home. The nice lady customs inspector inquired as to how I acquired a gold medal. My wife told her that it was the Nobel medal I had just received in Stockholm. To my surprise, she not only knew what this was but shook my hand, saying that I was the second Nobel laureate she had had the pleasure to meet personally (the other was Linus Pauling). She decided that my acquisition of the medal did not come under the duty rules. I hope neither of us will get into any trouble for it.  [c.185]

I have always enjoyed teaching and direct contact with my students. Teaching chemistry varies in its approach at different levels. Early courses for nonmajor undergraduates should provide sufficient, but not in-depth, introduction emphasizing the wonderful, magic world of chemistry and its broad applications as well as its significance to the other sciences. Regrettably, chemistry frequently is still thought of as a rather dry discipline based primarily on physical laws. However, chemistry can be taught, even while acknowledging physical principles, as a vibrant, exciting topic with much relevance to and examples from our everyday life and the challenges and problems of mankind. Linus Pauling taught such a course at Caltech for years, and there is indeed a shift these days toward teaching more relevant, interesting chemistry courses.  [c.239]

In the late nineteenth and early twentieth centuries major discoveries about the nature of atoms placed theories of molecular structure and bonding on a more secure founda tion Structural ideas progressed from simply identifying atomic connections to attempt mg to understand the bonding forces In 1916 Gilbert N Lewis of the University of Cal ifornia at Berkeley described covalent bonding m terms of shared electron pairs Linus Pauling at the California Institute of Technology subsequently elaborated a more sophis heated bonding scheme based on Lewis ideas and a concept called resonance, which he borrowed from the quantum mechanical treatments of theoretical physics  [c.3]


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Modern inorganic chemistry (1975) -- [ c.50 ]