Valency, auxiliary

In this volume it has been found convenient to retain, in many cases, Werner s original conception of principal and auxiliary valencies. 

The optical investigation described does not indicate any such difference, and by this and other observations it seems likely that there is no essential difference between principal and auxiliary valency. 

Molecular Formula —Co-ordination Theory of Valency—Principal and Auxiliary Valency—Co-ordination Complex—Co-ordination Number—Ionised Valency, Co-valeney, Co-ordinate Valency. 

The formation of sulphuric and chlorosulphuric acids by the union of sulphur trioxide with water and hydrogen chloride respectively is brought about by the secondary valencies as indicated in the schemes 03S+0H2=03S. . . OH2 and 03S+C1H=03S. . . C1H. When one of the reacting molecules contains douhle-linked atoms, the auxiliary valencies may not he sufficiently strong to preserve the integrity of the new mol., and, the atoms of the addition product may be rearranged. For example, this is the case with sulphur trioxide. Thus ... 

The latter formula has been established in a manner similar to the former. A. Werner assumes that four of the chlorine atoms are attached to platinum by principal valencies, and two by auxiliary valencies and that the last two chlorine atoms are not saturated so that the hydrogen atoms may attach themselves at these points. T. M. Lowry modified the idea by assuming that the quadrivalent platinum atom begins by attracting to itself a shell of six chlorine ions as in la of the following schemes where the electrostatic attractions or electrovalencies are represented by dotted lines. The orientation of these six ions is identical with that of the six chlorine ions distributed about each ion of sodium in a crystal of sodium chloride-16. The outer shell... 

I used these tables of Preul for the first part of my doctoral work. The computation of integrals for a valence bond treatment of the H-F molecule on a mechanical desk calculator was greatly simplified by the fact that I could look up values for the required auxiliary functions in these tables. Toward the end of this work (1962-1963), I got access to the electronic computer Z23, which of course could perform the calculations in a much shorter time with much higher accuracy. 

Alfred Werner was born in 1866 and died from arteriosclerosis in 1919, He started as an organic chemist and finished his chemical career in 1915 as one of the foremost inorganic chemists,. He won the Nobel Prize in 1913, During a period of two and a half decades he published 174 papers and supervised the work covered by 200 doctoral dissertations, Werner was the founder of coordination chemistry. He rejected the then prevailing concept formulated by Kekule) that the valence of an element is invariable and introduced instead the notion of principal and auxiliary valence. He also formulated the concept of coordination number, Werner used both the inductive and the deductive methods of reasoning. Most of his predictions on geometrical and optical isomerism were verified by experiment. 

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