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Chemical trends

Wachutka G, Fleszar A, Maca F and Scheffler M 1992 Self-consistent Green-function method for the calculation of electronic properties of localized defects at surfaces and in the bulk J. Phys. Condens Matter A 2831 Bormet J, Neugebauer J and Scheffler M 1994 Chemical trends and bonding mechanisms for isolated adsorbates on Al(111) Phys. Rev. B 49 17 242... [Pg.2237]

Chemical trends within Group 14 are discussed on p. 373. Silicon does not form binary compounds with the heavier members of the group (Ge, Sn, Pb) but its compound with carbon, SiC,... [Pg.332]

We have already observed (in Exercise 21-2) that the alkaline earths have similar chemistry. As shown in Table 21-1, they have similar electron configurations. Table 21-111 shows that each element has two valence electrons. With these basic likenesses in mind we shall explore the chemical trends among these elements. [Pg.381]

Ion formation is only one pattern of chemical behavior. Many other chemical trends can be traced ultimately to valence electron configurations, but we need the description of chemical bonding that appears in Chapters 9 and 10 to explain such periodic properties. Nevertheless, we can relate important patterns in chemical behavior to the ability of some elements to form ions. One example is the subdivision of the periodic table into metals, nonmetals, and metalloids, first introduced in Chapter 1. [Pg.552]

Since energy differences involving configurational changes are among the most challenging to compute accurately, one may conclude that B3LYP/6-311++G reproduces the chemical trends fairly satisfactorily (mean absolute deviation 0.22 eV). [Pg.78]

The parameter [3 is related to the contrast. If (3A> > 1, equation 1 reduces to that of a simple first order reaction (such as CEL materials are usually assumed to follow (6)). If 3A< < 1, the reaction becomes second order in A In a similar manner, the sensitized reaction varies between zero order and first order. For the anthracene loadings required by the PIE process (13,15), A is close to 1M, so (3 > > 1 is required for first order unsensitized kinetics. Although in solution, 3 for DMA is -500, and -25 for DPA (20), we have found [3 =3 for DMA/PEMA, and (3=1 for DPA/PBMA. Thus although the chemical trends are in the same direction in the polymer as in solution, the numbers are quite different, indicating a substantial... [Pg.339]

A. Archelas, R. Furstoss, Epoxide Hydrolases. New Tools for the Synthesis of Fine Organic Chemicals , Trends Biotechnol. 1998, 16, 108 - 116. [Pg.669]

The term noumenon (in the sense of Kantian philosophy) is deadly correct for describing atoms-in-a-molecule as a conceptual construct ultimately unknowable by observation or unique definition, but conceivable by reason. Cbemical science is built upon the atom, and the atom in a molecule is a vital, central concept, yet forever elusive there are multiple ways to partition molecules into atoms that ate consistent with various observed chemical trends and experimental data. [Pg.51]

However, test bums that were conducted at a single facility to study the effects of adding TDF to a base fuel reveal chemical trends that may be similar to those observed at other facilities, and thus could be useful for assessing ash disposal and groundwater protection strategies. [Pg.485]

Review operational parameters . Chemical trend reports ... [Pg.749]

Iron meteorites offer the unique opportunity to examine metallic cores from deep within differentiated bodies. Most of these samples were exposed and dislodged when asteroids collided and fragmented. Although irons constitute only about 6% of meteorite falls, they are well represented in museum collections. Most iron meteorites show wide variations in siderophile-element abundances, which can be explained by processes like fractional crystallization in cores that mimic those in achondrites. However, some show perplexing chemical trends that may be inconsistent with their formation as asteroid cores. [Pg.180]

Currently, there are five approved HIV protease inhibitors available which are mostly used in combination therapy with other drugs, such as reverse transcriptase inhibitors (NTIs). Most HIV protease inhibitors are still synthesized chemically. Trends apparent during the development of HIV protease inhibitors are (i) the labile amide bond of peptides is replaced by isosteres such as hydroxyethylamine ... [Pg.373]

Cooney, R. R., and Urquhart, S. G. (2004). Chemical trends in the near-edge X-ray absorption fine structure of monosubstituted and para-bisubstituted benzenes. J. Phys. Chem. B 108, 18185-18191. [Pg.773]

The nature of the rock record from the time of the first sedimentary rocks ( 3.8 billion years ago) to about 1 to 2 billion years ago suggests that the amount of oxygen in the Earth s atmosphere was significantly lower than today, and that there were continuous chemical trends in the sedimentary rocks formed and, more subtly, in hydrosphere composition. Figure 10.6 illustrates how the chemistry of rocks shifted dramatically during this transitional period. The source rocks of sediments during this time may have been more basaltic than later ones ... [Pg.589]

Generally, VB theory is seen to offer a widely applicable framework for thinking and predicting chemical trends. Some of these qualitative models and their predictions are discussed in the application sections of this book. [Pg.15]

Unlike the case with the d orbitals in the transition elements, spectra and magnetism associated with 4/ orbitals in Ln3+ compounds are very similar to those found in free gas-phase ions. Ligand field and chemical bonding effects associated with incomplete 4/orbitals are very small and hardly detectable in chemical trends. [Pg.277]

Basic data on the physical properties of indium nitride are sparse and the following sections include instances of values uncorroborated by repeated measurement. In cases where data are absent, the chemical trends across the nitride group have made it possible for first-order estimates to be made and these are included where thought appropriate. The reader is invited to consider these extrapolations by consulting firmer values for AIN and GaN elsewhere in this volume more firmly established data await the advent of better quality material. [Pg.123]

Cheetham AK, Rao CNR, Feller RK. Structural diversity and chemical trends in hybrid inorganic-organic frameworkmaterials. Chemical Communications. 2006 42(46) 4780-4795. [Pg.306]

Structural diversity and chemical trends in hybrid inorganic-organic framework materials... [Pg.409]

Accurate and precise identifications and measurements of specific chemical substances are fundamental to environmental studies and protection programs. Determinations are required to understand natural background concentrations of chemicals in the environment, the nature and extent of environmental pollution by anthropogenic chemicals, trends in concentrations of these substances, the transport and fate of chemical substances, and the causes of variations of concentrations intime and space. Accurate and precise determinations are also required to assess human health and ecological risks caused by exposure to natural and anthropogenic substances, establish air and water quality standards, develop pollution control strategies, evaluate the effectiveness of pollution prevention and treatment technologies, and monitor compliance with and the effectiveness... [Pg.305]

Whereas JAB involves the nuclear magnetogyric ratios, the reduced coupling constant KAB represents only the electronic contribution and is thus approximately isotope independent and may exhibit chemical trends. [Pg.25]

Archelas A, Furstoss R (1998) Epoxide hydrolases New tools for the synthesis of fine organic chemicals. Trends Biotechnol 16 108-116... [Pg.337]


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See also in sourсe #XX -- [ Pg.151 ]




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