Fundamental terms, notions

The explication of reduction in terms of property structures proposed here is more fundamental than notions of theory reduction, it is not more expensive in semantic or metaphysical respects, and it does not, unlike holistic notions of reduction, rely on conditions arrived at by extension j m-criteria, i.e. by the examination of alleged cases of reductions. These conditions are in need of explanation. This explanation is provided by the explication of reduction offered above (we will turn to the explanation of why reduction goes together with at least some forms of unification in the next chapter). Moreover, the definition proposed here does not face a problem when confronted with ontologically equivalent pairs of reduced and reducing theories. 

The expert is aware that the electron s history has no significance, but a learner may well expect there to be a greater attraction between an atomic core and the bonding electron that belongs to that atom (Taber, 1998). Such beliefs may seem rather bizarre for those used to thinking of chemistry in terms of fundamental concepts (such as energy and forces), but actually reflect one of the basic principles of magic that seem to commonly influence people s intuitions about the natural world (Nemeroff Rozin, 2000). Indeed the notion that a past association leaves some... 

As a result, the limited ability of unit processes to create a viable niche for themselves within chemical engineering must ultimately be understood in terms which also involve unit operations. Although the historical resilience of unit processes turned out to be less than that of unit operations, it was no different in its essential elements. Studying the uneasy and ultimately unsuccessful career of unit processes can therefore be easily justified as a way to shed light on the far more successful career of unit operations. In particular, the career of unit processes raises a hypothesis about the evolution of unit operations. The staying power of unit operations was not so much because of the structural coherence of its conceptual elements as its essential links with social and, more specifically, professional groups. As a theoretical entity, unit operations appears far less stable and, in fact, appears quickly threatened by notions which rest on fewer and more fundamental scientific concepts. Ultimately, this threat came to be realized with the advent of transport phenomena, but this is another story. In effect, unit processes can be interpreted as both the attempt to extend the reach of unit operations and a symptom of their conceptual fragility. 

What he does not seem to realize is that a perfectly good explanation existed for chemical bonding prior to the advent of the quantum mechanical explanation, namely Lewis s theory whereby pairs of electrons form the bonds between the various atoms in a covalently bonded molecule. Although the quantum mechanical theory provides a more fundamental explanation in terms of exchange energy and so on is undeniable but it also retains the notion of pairs of electrons even if this notion is now augmented by the view that electrons have anti-parallel spins within such pairs. 

Classes of Estimation Methods Table 1.1.1 summarizes the property estimation methods considered in this book. Quantitative property-property relationships (QPPRs) are defined as mathematical relationships that relate the query property to one or several properties. QPPRs are derived theoretically using physicochemical principles or empirically using experimental data and statistical techniques. By contrast, quantitative structure-property relationships (QSPRs) relate the molecular structure to numerical values indicating physicochemical properties. Since the molecular structure is an inherently qualitative attribute, structural information has first to be expressed as a numerical values, termed molecular descriptors or indicators before correlations can be evaluated. Molecular descriptors are derived from the compound structure (i.e., the molecular graph), using structural information, fundamental or empirical physicochemical constants and relationships, and stereochemcial principles. The molecular mass is an example of a molecular descriptor. It is derived from the molecular structure and the atomic masses of the atoms contained in the molecule. An important chemical principle involved in property estimation is structural similarity. The fundamental notion is that the property of a compound depends on its structure and that similar chemical stuctures (similarity appropriately defined) behave similarly in similar environments. 

Some notions of the mechanism of electron transfer were given in Section 4.2. Any theory must be realistic and take into account the reorientation of the ionic atmosphere in mathematical terms. There have been many contributions in this area, especially by Marcus, Hush, Levich, Dog-nadze, and others5-9. The theories have been of a classical or quantum-mechanical nature, the latter being more difficult to develop but more correct. It is fundamental that the theories permit quantitative comparison between rates of electron transfer in electrodes and in homogeneous solution. 

The origins of the present three-dimensional molecular-level branching concepts can be traced back to the initial introduction of infinite network theory by Flory [62-65] and Stockmayer [66, 67], In 1943, Flory introduced the term network cell, which he defined as the most fundamental unit in a molecular network structure [68]. To paraphrase the original definition, it is the recurring branch juncture in a network system as well as the excluded volume associated with this branch juncture. Graessley [69, 70] took the notion one step further by describing... 

Thus, we have three important concepts in the nineteenth-century scheme initiated by Lavoisier considerably earlier. The abstract element is a property bearer and owes its heritage to the Aristotelian element scheme. In addition to being a property bearer, the abstract element is an indestructible material ingredient of substances, and as we saw in the preceding discussion, there is a fundamental distinction between abstract element and simple substance. Abstract elements are unobservable, whereas simple substances such as sodium, chlorine, and oxygen are observed. It should be noted that in contemporary chemistry we only seem to retain the latter notion in that the term element now means what to a nineteenth-century chemist would have been called a simple substance ... 

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