Elaboration knowledge description

Scanning electron microscopy and other experimental methods indicate that the void spaces in a typical catalyst particle are not uniform in size, shape, or length. Moreover, they are often highly interconnected. Because of the complexities of most common pore structures, detailed mathematical descriptions of the void structure are not available. Moreover, because of other uncertainties involved in the design of catalytic reactors, the use of elaborate quantitative models of catalyst pore structures is not warranted. What is required, however, is a model that allows one to take into account the rates of diffusion of reactant and product species through the void spaces. Many of the models in common use simulate the void regions as cylindrical pores for such models a knowledge of the distribution of pore radii and the volumes associated therewith is required. 

To our knowledge, apart from a brief and elementary outline of a new approach developed by the present authors (5), no simple systematic didactic method for accomplishing the aforementioned goals has been reported (particularly for polyatomic molecules). While excellent introductory descriptions of bonding concepts exist (6,7), no attempts seem to have been made to find a pictorial substitute for a substantial portion of group theory as applied to molecular orbitals or to elaborate in detail the equivalence of the localized and delocalized bonding views on an elementary level. Our approach has been developed and tested in a freshman chemistry course for majors at Iowa State University for a number of years. In the present paper we give and justify a more elaborate discussion of this pictorial method which leads to delocalized and localized MO s for a wide variety of polyatomic molecules. The key concept is that delocalized and localized MO s can be deduced from an appropriate extension of the characteristics of AO s. More specifically, the symmetry and directional characteristics of MO s are obtained from the symmetry and directional characteristics of AO s. 

The only hmitation is one s own knowledge as to the process to be modeled. The program PHREEQC can be obtained from the internet as public domain software, including an elaborate, very informative description and many examples, at ... 

The third part, perhaps the most significant, contains the synthesis of various important members treated individually, brief description of the synthesis, therapeutic applications of each compound, together with its dosage in various diseases, and routes of administration. The dosage for adults and children have been separately mentioned. The usual and maintenance doses, wherever applicable, have also been specified. The mode of action of various classes of medicinal compounds in addition to the structure-activity relationship (SAR) have also been elaborated wherever relevant. Greater emphasis has been laid on the chemistry of various compounds treated in this book, so that an undergraduate student may acquire a comprehensive knowledge on the basic concepts of the medicinal chemistry. 

Although little use is made now of the theory presented in this chapter, it contains the basis of all of those that are used. It provides the foundation, particularly for the understanding of spectral and magnetic properties all else is elaboration and refinement. A knowledge of simple crystal field theory is therefore essential to an understanding of the key properties of transition metal complexes and particularly those covered in Chapters 8 and 9. This chapter deals exclusively with transition metal complexes. In one or more of their valence states, the ions of transition metals have their d orbitals incompletely filled with electrons. As a result, their complexes have characteristics not shared by complexes of the main group elements. It is the details of the description of these incompletely filled shells which is our present concern this is in contrast to the discussion of the previous chapter where the topic was scarcely addressed. Ions of the lanthanides and actinides elements have incompletely filled f orbitals and so necessitate a separate discussion which will be given in Chapter 11. 

In order to calculate an absorption spectrum, knowledge of the ground state, however, is not enough. We need also a proper description of the excited state, since excitations are processes that involve both. Here, the above-mentioned methods break down. In some cases it is possible to use external constraints, like an externally fixed (non-ground-state) multiplicity, to describe excited states with a ground-state method. But besides these exceptions we need to use more elaborate approaches to get a good picture of an excitation. 

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