Relation to Other Properties

The most obvious correlation of the electronegativity scale with the general chemical properties of the elements bears on their division into metals and nonmetals. It is seen that the value x = 2 represents ap- 

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MohsAn early (1822) hardness comparison test involved assigning a relative number to aH known materials (usuaHy minerals and pure metals) by virtue of their relative abHity to scratch one another. The results of this classification are not relatable to other properties of materials or to other measures of hardness. As a result of this limited useflilness, the Mohs hardness test is primarily used for mineral identification. Some examples of the Mohs hardness scale, which ranks materials from 1 to 10, are Hsted in Table 6. 

Recalling that a separation is achieved by moving the solute bands apart in the column and, at the same time, constraining their dispersion so that they are eluted discretely, it follows that the resolution of a pair of solutes is not successfully accomplished by merely selective retention. In addition, the column must be carefully designed to minimize solute band dispersion. Selective retention will be determined by the interactive nature of the two phases, but band dispersion is determined by the physical properties of the column and the manner in which it is constructed. It is, therefore, necessary to identify those properties that influence peak width and how they are related to other properties of the chromatographic system. This aspect of chromatography theory will be discussed in detail in Part 2 of this book. At this time, the theoretical development will be limited to obtaining a measure of the peak width, so that eventually the width can then be related both theoretically and experimentally to the pertinent column parameters. 

The concept of a characteristic reaction temperature must, therefore, be accepted with considerable reservation and as being of doubtful value since the reactivity of a crystalline material cannot readily be related to other properties of the solid. Such behaviour may at best point towards the possible occurrence of common controlling factors in the reaction, perhaps related to the onset of mobility, e.g. melting of one component or eutectic formation, onset of surface migration or commencement of bulk migration in a barrier phase. These possibilities should be investigated in detail before a mechanism can be formulated for any particular chemical change. 

It is the a and coefficients that must be manipulated to obtain a new set of attributes that correspond to a liquid other than water. Of course, this relationship is only with the value of the viscosity, but it may relate to other properties. 

Other drugs that have an impact on serum lipids have also been examined. Probucol pretreatment has been shown to lower the rate of restenosis after balloon angioplasty in clinical trials (88,89). Although its lipid-lowering effect is due to an increase in the fractional catabolic rate of LDL cholesterol (90), its antirestenotic effect is believed to be related to other properties, including inhibition of LDL oxidation, promotion of endothelial regeneration, and anti-inflammatory effects (91). However, probucol is not widely available due to its ability to lower HDL-cholesterol and concerns relating to proarrhythmia. 

Since the surface tension is a manifestation of intermolecular forces, it may be expected to be related to other properties derived from intermolecular forces, such as internal pressure, compressibility and cohesion energy density. This is found to be so indeed. In the first place there exists a relationship between compressibility and surface tension. According to McGowan (1967) the correlation is ... 

The effects of BZ and Dltran, compared with atropine and scopolamine, have been examined to elucidate the mechanisms by which these ccaapounds produce their effects. All these compounds have an extremely high affinity for muscarinic receptor sites, so the higher potency and longer duration of action of BZ must be related to other properties. 

These relations have been partly commented upon in the preceding text. Since the Stokes shift for these complexes does not relate to one and the same transition (singlet-singlet in excitation, triplet-singlet in emission), we do not discuss its relation to other properties further. 

The temperature quenching of the luminescence of the complexes can be related to other properties. This situation asks for quantitative calculations as have been performed for other centres (uranates with charge-transfer transitions )). 

The magnetic changes which occur during the dehydration of chromia gel, and their relation to other properties, are described below (Davis, 25). 

Data on grain size distribution of the various strata is important to the overall site characterization and provides information related to other properties and behavior, such as permeability and water flow. Two main concerns are testing procedures and texture (grain size) classification systems. At present, there is no universally accepted classification system and testing methods can be quite different. The presence of significant biogenous materials, effects of flocculation due to salts, and the fact that some deep-sea clays are extremely fine-grained, requires that special procedures be considered. 

A cmcial component of this treatment is the value of P°w for the distribution of the solute molecules between 1-octanol and water. This could be estimated from group contributions (Hansch and Leo 1979) but could also be related to other properties of the solutes, namely, their solvatochromic parameters according to Kamlet et al. (1984,1988). Their equation was tested for 245 solutes of all kinds with a correlation coefficient of 0.996 and a standard deviation of 0.13. Earlier, Kamlet, Taft and coworkers (Taft et al. 1985, Kamlet et al. 1986) applied the LSER concept directly to the solubility of non-electrolytes in water, independently of the octanol/water distribution. Subsequently, important differences between aliphatic and aromatic solutes were stressed (Kamlet et al. 1987). For liquid aliphatic solutes the expression ... 

A second item of terminology is that I use the terms second order and first order not in the sense of properties of properties versus properties of individuals, but as follows a second-order property is a property that has a true definition in terms of having some other properties that meet a certain sort of condition. And a first-order property does not have such a true definition. A functional property is a special kind of second-order property in which the definition specifies causal relations to other properties and to inputs and outputs. I am supposing that the other properties quantified over in the second-order definition are themselves first-order properties. 

Figures 2.3.2 to 2.3.6 illustrate how the boiling points of individual solvents in a group are related to other properties. Figure 2.3.2 shows that chemical structure of a solvent affects the relationship between its viscosity and the boiling point. Alcohols, in particular, show a much larger change in viscosity relative to boiling point than do aromatic hydrocarbons, esters and ketones. This is caused by strong associations between molecules of alcohols, which contain hydroxyl groups. Figure 2.3.3 shows fliat alcohols are also less volatile...

The electrochemical characteristics of synthetic derivatives of uridine, cytosine and their orohi/io-analogues, including deoxythio- and cyclo-analogues, have been examined and related to other properties (i.e., h.p.l.c., tnological, onymatic reactivity, and lipophilicity). ... 

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