Ordering principles

Chemical nomenclature deals with names of elements and their combinations. Whereas writing the symbol or the name of an element is straightforward, a choice of which element to write first in the formula and in the name has to be made as soon as an element is associated with one or more other elements to form, for example, a binary compound. The order of citation of elements in formulae and names is based upon the methods outlined below. Furthermore, groups of atoms, such as ions, ligands in coordination compounds and substituent groups in derivatives of parent hydrides, are ordered according to specified rules. 

SrFe03 iron strontium oxide cf. Example 5 above) 

A similar rule applies when citing names of substituent groups in substitutive nomenclature (see Section IR-6.3.1). 

Where there is a choice of parent hydrides among those listed in Table IR-6.1 (or corresponding hydrides with non-standard bonding numbers, cf. Section IR-6.2.2.2), the name is based on the parent hydride of the element occurring first in the sequence  

This applies in particular to the naming of organometallic compounds of elements of groups 13-16 when a choice has to be made between several parent hydrides (Section IR-10.3.4). 

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But as argued in a recent book, once one accepts that the more correct ordering principle for the elements is atomic number the concept of triads makes a significant return, at least in about half of all conceivable triads in the modern table (6). Using the atomic numbers of chlorine, bromine, and iodine for example the middle element is not just the approximate mean of the atomic numbers of the flanking elements but the exact mean. 

Aside from the ordered stacking sequences we have considered so far, a more or less statistical sequence of hexagonal layers can also occur. Since there is some kind of an ordering principle on the one hand, but on the other hand the periodical order is missing in the stacking direction, this is called an order-disorder (OD) structure with stacking faults. In this particular case, it is a one-dimensionally disordered structure, since the order is missing only in one dimension. When cobalt is cooled from 500 °C it exhibits this kind of disorder. 

Carbb, R., Calabuig, B., Vera, L. and Besalu, E. (1994) Molecular quantum similarity theoretical framework, ordering principles, and visualization techniques. In Advances in Quantum Chemistry, Vol. 25, Lowdin, P.-O., Sabin, J.R. and Zemer, M.C. (Eds.), Academic Press, New York. 

The periodic system of the elements is not a human invention. This ordering principle is rooted in the fundamental secrets of nature. Each element has its determined place and its specific identity. 

Carbo, R., B. Calabuig, L. Vera, andE. Basalu. 1994. Molecular Quantum Similarity Theoretical Framework, Ordering principles, and Visualization Techniques. 25, 253. 

The ordering principle of this section is different to the preceding section on the isolated molecules or molecular ions. We start with the structures of the elements and then classify the polymeric Te structures by the number of atoms in the constituting homocycles, i.e. four-, five- and six-membered rings. 

The lack of a single ordering principle is a shortcoming particularly for the gallium clusters, since there are a larger number of them compared with the corresponding aluminum clusters as a result of their improved synthesis procedures (cf. Section 2.3.3). A purely formal means of classification for the gallium clusters... 

For Laurent, who used metaphors of the chemical tree and the biological nucleus, the type was an ordering principle of extraordinary power. Berzelius was suspicious of this orientation because it was at odds with his theory of electrical polarities between elementary substances. 53... 

Most psychotropic medications are given orally and are absorbed after dissolution, primarily in the small intestine. The rate of absorption (expressed as a rate constant Ka [1/h]) is usually passive and obeys first-order principles, meaning that the rate of absorption is dependent on the amount of drug at the site of absorption, with a constant fraction absorbed per unit of time. 

The metal ion has proven to be a useful order-principle in sorting the data despite its limitations for proteins containing different ions. 

To provide an overview chemical constitution and synthesis are combined in this section. The various application media for metal-complex dyes are a further ordering principle, which generates overlap of some sections with reactive dyes (Section 3.1), leather dyes (Section 5.1), and paper dyes (Section 5.3), demonstrating the typically complex interrelationship of constitution and application of dyes. 

Quadrupolar nuclei to probe local ordering principles and selected applications (8)... 

The plethora of entries in Tables 17.3 and 17.4 emphasizes that organic chemical redox reactions are not limited to one mechanism and are not even based on a small number of mechanistic principles. Hence, one should not expect any mechanistic homogeneity among the reactions to be discussed in Chapter 17. Sections 17.3 (oxidations) and 17.4 (reductions) are thus not organized on the basis of mechanistic considerations. Instead, the ordering principle reflects preparative aspects Which classes of compounds can be oxidized or reduced into which other classes of compounds, and how can these transformations be accomplished ... 

We first discuss some basic aspects of surface structures, including ordering principles and notations, followed by an overview of the number and types of surface structures that have been investigated. Finally we shall highlight a few major trends emerging from the structural results. 

The enormous number of different chemical species with their multitude of properties can be classified into various categories, provided some ordering principles are> discovered and used to associate the various species with different classes. It is with this in mind that already in 1835 Berzelius[l] introduced a classification of chemical species according to a scale of electronegative and electropositive character. He wrote ... 

Molecular Devices. Chiral, Bichromophoric Silicones Ordering Principles in Complex Molecules... 

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