Older symbols

Toward the end of the eighteenth century chemists began to make use of initial letters of the names of elements and compounds, instead of the older symbols. Berzelius then systematized this procedure, and his scheme was soon adopted bv all diemists. 

Re (Njifi. An alternate, older symbol for Reynolds number. 

Further steps toward universality are taken by the replacement of element and compound names wherever possible by symbols and formulas, and by adding to data in older units their recalculated SI equivalents. The usefulness of the reference sections has been increased by giving journal-title abbreviations according to the Chemical Abstracts Service Source Index, by listing in each reference all of its authors and by accompanying references to patents and journals that may be difficult to access by their Chemical... 

In this chapter, we focus on recent and emerging technologies that either are or soon will be applied commercially. Older technologies are discussed to provide historic perspective. Brief discussions of potential future technologies are provided to indicate current development directions. The chapter substantially extends an earlier publication (Davis et al., 1996a) and is divided into seven main sections beyond the introduction Data Analysis, Input Analysis, Input-Output Analysis, Data Interpretation, Symbolic-Symbolic Interpretation, Managing Scale and Scope of Large-Scale Process Operations, and Comprehensive Examples. 

Physical quantities relevant to analytical measurements and the units and symbols used to express them are given in Table 1.3. Both SI and CGS units have been included because of current widespread use of the latter and for ease of comparison with older literature. However, only the SI nomenclature is now officially recognized and the use of the CGS system should be progressively discouraged. 

Number of electrons (n). There is one final divergence from standard lUPAC usage that may cause confusion. In normal thermodynamics, the symbol n is used for amount of substance . An older convention is followed in electroanalytical work, and electrochemistry in general, such that n means simply the number of electrons involved in a redox reaction. Normal lUPAC representation would use V for this latter parameter since the number of electrons is a stoichiometric quantity. The opposition from electrochemists has been so concerted that lUPAC now allows the use of n as a permissible deviation from its standard practice. 

In spite of the fact that a six-state model is a natural choice for describing the conformational distribution in PIB chains, a simpler model can be obtained by labeling all the bond conformations in the domain [60,160°] and all those in the domain [-60, - 180°I with the symbols g+ and g , respectively. This leads to a four state model formally analogous to the older ones but leaves the exact location of the gauche states undefined. 

Area. II. We have previously designated the /th representation, or its set of characters, by the symbol T, in a fairly arbitrary way. Although this practice is still to be found in some places and is common in older literature, most books and papers—in fact, virtually all those by English-speaking authors— now use the kind of symbols found in the C3v table above and all tables in Appendix II. This nomenclature was proposed by R. S. Mulliken, and the symbols are normally called Mulliken symbols. Their meanings are as follows ... 

The inner shells of cere elecirofiS are often abbreviated since no nei bonding takes place in them. The symbols used, K, L. M. elc refer lo the older system of designating the principal energy levels, n = I (K). n = 2 (L), etc. Thus Na2 = KK LL oj, ... 

The space group symbol Cmce now replaces the older form, Cmca. Na atoms represent unresolved cations and water in the channels. 

In the second case the standard hydrogen electrode is placed on the right-hand side of the representation of the cell, and the other electrode would be placed on the left-hand side. The emf of the cell would then be written as = i a — ij/c. The value of if/f is defined to be zero and the potential of the electrode on the left, t a, is the emf of the cell. The symbol ip is called the oxidation potential. When all of the reacting substances of the electrode are in their standard states, then // would become ip° and would be called the standard oxidation potential. This terminology is that of Latimer and emphasizes the nature of the reaction taking place at the electrode. We present it here for completeness, knowing that reduction potentials are now the standard convention, but that some of the older literature used oxidation potentials. 

Symbol Gibbs free energy is denoted eponymously by G, after Josiah Willard Gibbs, ca. 1873, who single-handedly created much of chemical thermodynamics. In the older literature F was sometimes used. Equation since G = H TS, the free energy of a molecule can be calculated from its enthalpy (above) and entropy at temperature 7 the entropy is calculated by standard statistical mechanics methods [130]. 

---