Basic entity

When we use any substance as a solvent for a protonic acid, the acidic and basic species produced by dissociation of the solvent molecules determine the limits of acidity or basicity in that solvent. Thus, in water, we cannot have any substance or species more basic than OH or more acidic than H30 in liquid ammonia, the limiting basic entity is NHf, the acidic is NH4. Many common inorganic acids, for example HCl, HNO3, H2SO4 are all equally strong in water because their strengths are levelled to that of the solvent species Only by putting them into a more acidic... 

A new class of conjugated hydrocarbons is that of the fullerenes [11], which represent an allotropic modification of graphite. Their electrochemistry has been studied in great detail during the last decade [126]. The basic entity within this series is the Ceo molecule (23). Because of its high electron affinity, it can be reduced up to its hexaanion (Fig. 4) [14,127]. Solid-state measurements indicate that the radical anion of Ceo reversibly dimerizes. NMR measurements confirm a u-bond formation between two radical anion moieties [128,129]. 

If a multitude of individual waveguides is eontained in a complex eireuitry, then parametric models for basic entities are preferentially used, whieh apply to the optieal signal level, i.e. to complex (mode) amplitudes. 

The characteristics of those basic entities like power splitters, combiners, directional couplers etc. can be related to some basic waveguide properties, and the 4-port devices are described by 2 x 2 matrices, Eqs(28),... 

The interaction between selective metal oxides and molecules to be oxidized is, of course, based on electron-accepting and electron-donating properties, respectively. In this way, Mo6+, Vs+, etc. act as electron acceptors and molecules with 7r-bonds as donors. Ai et al. [5—12] have drawn attention to the fact that this can also be described by acid—base properties. An electron donor molecule like butene is a basic entity interacting with acidic sites on the catalyst. Hence it follows that activity and selectivity depend on the relative acidity and basicity. Mo03, for example, is an acidic oxide, while Bi203 is a basic oxide. Different compositions Bi Mo have different acidities. The rate of oxidation depends on the number of acid sites (=acidity) and the acid strength, viz. 

The ways in which chemists most frequently express concentrations involve the mole as the concentration unit (rather than the gram), because reactions are between molecules as the basic entities. 

The most basic entity in mechanics is the mass point. It is one of the earliest and most fruitful abstractions in physics. The mass point is an extrapolation from real slabs of matter to something that has no form... 

If the odors of specific objects translate into unitary percepts, which constitute the basic entities in linguistic descriptions of olfaction, then the question follows as to whether these unitary percepts take shape at the level of the receptor neurons or in the olfactory bulb or elsewhere in the brain. That question remains unanswered, as of this writing. Because the sense of smell does not correlate perfectly with externally monitored patterns of electrical response from the receptor neurons or the olfactory bulb, the nature of olfactory coding remains unknown. Outside the laboratory unitary percepts rarely equate to pure compounds. Two vocabularies coexist, one of smells (which varies from individual to individual, and which refers to other inputs besides olfaction) and the other of chemical structures. 

Photolabile linkers are stable under a number of reaction conditions in organic synthesis, and they also allow release under neutral conditions. Photolabile linking groups for hydroxy and amino functions can be divided into three different basic entities, as shown in Fig. 13. 

There are a number of representations that are considered fundamental descriptions of the basic entities in various fields. The Mass-Action representation and the Michaelis-Menten representation provide two common examples. It has been demonstrated (Savageau, 1995) that these are, in fact, restricted special cases of the Generalized-Mass-Action (GMA) representation. 

The basic single-particle nature of the expectation values follows from the generator acting only on the coordinates of a single electron in the field theoretic expressions, Schwinger pointing out that "the essence of field theory is to provide a conceptually simpler and more fundamental description depending on the particle as the basic entity" [7],... 

If one examines the most potent and commonly used local anaesthetics in the therapeutic armamentarium it may be abimdantly clear that they essentially possess a tertiary alkylamine moiety which rapidly converts the base into the corresponding water-soluble salts with the various mineral acids. Obviously, the basic entity is frequently regarded as the hydrophilic entity of the drug molecule. 

Naturally, the basic entity from where the chemical reactivity starts and the chemistry as a science itself, is the atom with its electron cloud. Ultimately, from this entity and from its properties should start the basic study for defining the global properties of the electronic distribution and the tendency of evolution of this distribution defined through die electronegativity. 

Figure 6-12 Basic entity types for definition of the machining task.

Heterogeneity — the basic entities of the pore space are not simply cylinders, but have size distributed bodies and throats. 

Very often the chemical properties of a molecule or of a functional group are governed by a few electrons. For instance, the donor properties and proton affinity of ammonia can be understood from the character of its lone pair bonding properties of an alkyl radical depend on its unpaired electron. As these molecules or functional groups are basic entities in chemistry, it can be conjectured that they could be described by fragment pseudopotentials quite similar to the atomic pseudopotentials associated with the cores of the atoms. 

Today we know that the HF method gives a very precise description of the electronic structure for most closed-shell molecules in their ground electronic state. The molecular structure and physical properties can be computed with only small errors. The electron density is well described. The HF wave function is also used as a reference in treatments of electron correlation, such as perturbation theory (MP2), configuration interaction (Cl), coupled-cluster (CC) theory, etc. Many semi-empirical procedures, such as CNDO, INDO, the Pariser-Parr-Pople method for rr-eleetron systems, ete. are based on the HF method. Density functional theory (DFT) can be considered as HF theory that includes a semiempirical estimate of the correlation error. The HF theory is the basie building block in modern quantum chemistry, and the basic entity in HF theory is the moleeular orbital. 

In chemistry as well as in physics, advanced theories are held by two milestones (i) a mathematical structure/formalism disclosing the basic entities of the theory and their mathematical relationships, and (ii) an interpretative recipe of basic entities of the theory. The latter discloses the qualitative meaning of the basic entities and their relation to other known entities within and beyond the theory. It is important to highlight that the connection between the mathematical formalism and its interpretation is always subtle. This problem can be traced back to the lack of a clear and unambiguous definition of a bond in quantum mechanics and the plethora of interpretations that have been introduced with various meanings of the mathematical symbols/entities of the theory [15]. 

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