Ionic terminology

The initiators which are used in addition polymerizations are sometimes called catalysts, although strictly speaking this is a misnomer. A true catalyst is recoverable at the end of the reaction, chemically unchanged. Tliis is not true of the initiator molecules in addition polymerizations. Monomer and polymer are the initial and final states of the polymerization process, and these govern the thermodynamics of the reaction the nature and concentration of the intermediates in the process, on the other hand, determine the rate. This makes initiator and catalyst synonyms for the same material The former term stresses the effect of the reagent on the intermediate, and the latter its effect on the rate. The term catalyst is particularly common in the language of ionic polymerizations, but this terminology should not obscure the importance of the initiation step in the overall polymerization mechanism. 

When the substituent is an ionic chain [Fig. 13(b)] with the anion on the organic side, some of the lateral anions act as counter-ions during electrochemical oxidation. The cation of the salt is expelled from, or included in, the material during oxidation or reduction, respectively. These are self-compensating or self-doping (chemical or physical terminology, respectively) materials.76... 

Fire retardant treatment, for wood, 26 348 Fire science, 11 450 Fire test methods, 11 449—450 Fire test terminology, 19 588 Fire-tube furnaces, 12 319—320, 327 Firing, of ferrites, 11 73 Firming agents, 12 32 as food additives, 12 57 First aid and rescue, 21 858 First aid, for nitric acid exposure, 17 192 First failure, time to, 26 987 First falling rate period, 23 67 First-generation ionic liquids, 26 837-838, 841, 865... 

First, because neither the formation of P+nM nor the formation of P+nP involves a change of charge, the effect of changing the ionic concentration from 10 10 to, say, 10"4 mold"1 on the equilibrium constants is likely to be negligible. On the other hand, the effect of ionpairing on the complexation may be considerable in terms of our previous terminology we are now comparing K u [Equation (4)] with as defined by (16) and (17). 

The terminology applied in the different papers might vary. For example, both the terms buffer concentration and electrolyte concentration are frequently used and usually refer to the same. The same occurs for the terms buffer pH and electrolyte pH, and buffer ionic strength and electrolyte ionic strength. However, for the exact meaning or practical implications, we refer to the corresponding literature. 

At low pH (acidic solution), an amino acid will exist as the protonated ammonium cation, and at high pH (basic solution) as the aminocarboxylate anion. The intermediate zwitterion form will predominate at pHs between these extremes. The uncharged amino acid has no real existence at any pH. It is ironic that we are so familiar with the terminology amino acid, yet such a structure has no real existence Amino acids are ionic compounds, solids with a high melting point. 

Now, just the same sort of rationalization can be applied to the radical addition, in that the more favourable secondary radical is predominantly produced. This, in turn, leads to addition of HBr in what is the anti-Markovnikov orientation. The apparent difference is because the electrophile in the ionic mechanism is a proton, and bromide then quenches the resultant cation. In the radical reaction, the attacking species is a bromine atom, and a hydrogen atom is then used to quench the radical. This is effectively a reverse sequence for the addition process but, nevertheless, the stability of the intermediate carbocation or radical is the defining feature. The terminologies Markovnikov or anti-Markovnikov orientation may be confusing and difficult to remember consider the mechanism and it all makes sense. 

Terminology of polymers containing ionizable or ionic groups and of polymers containing ions (lUPAC Recommendations 2006), Pure Appl. Chem. 78, 2067-2074 (2006). Reprinted as Chapter 10, this edition. 

Terminology of polymers containing ionizable or ionic groups and of polymers containing... 

Terminology of Polymers Containing lonizable or Ionic Groups and of Polymers Containing Ions (2006), 205... 

In this case the zero-order electronic wave functions are, in principle, referred to a Hamiltonian that contains the potential from the ions at their actual positions, i.e., the electrons follow the ionic motion adiabatically. Since both these approximations are sometimes referred to as the Born Oppenheimer approximation, this has led to confusion in terminology for example, Mott (1977) refers to the Born-Oppenheimer approximation, but gives wave functions of the adiabatic type, whereas Englman (1972) differentiates between the two forms, but specifically calls the static form the Bom Oppenheimer method. [We note that, historically, the adiabatic form was first suggested by Seitz (1940)—see, for example, Markham (1956) or Haug and Sauermann (1958)]. In this chapter, we shall preferentially use the terminology static and adiabatic. [Note that the term crude adiabatic is also sometimes used for the static approximation, mainly in the chemical literature—see, for example, Englman (1972, 1979).]... 

In the following section we use the well-known and rather extensively studied silver iodide surface as a vehicle for introducing the basic concepts and terminology of charged surfaces and the nature of the ionic atmosphere that develops in the vicinity of such surfaces. 

Because radicals are uncharged, one would expect that electron donation and withdrawal would be less important than in ionic reactions. Although this expectation is certainly correct, there is nevertheless ample evidence that transition states of radical reactions do have some polar character. In resonance terminology, one might describe the transition state of a homolysis as a resonance hybrid (25) of covalent, radical, and ionic structures, with importance of the ionic forms subject to influence by substituents in A and B. It should therefore... 

The language that has developed to deal with this subtlety is to use the word concerted when both bonds are forming at the same time, without necessarily implying that they are developing to an equal extent, and to use the word synchronous when they are developing to an equal extent. Most pericyclic reactions are therefore concerted but asynchronous, since most pericyclic reactions do not have symmetrical components. This terminology makes it easy to appreciate that there is a continuity between pericyclic and stepwise ionic reactions, with a blurred borderline between them. 

These arguments have been debated for many years. Chemists who reject the use of nd orbitals in hybridisation schemes prefer three-centre bonds to describe hypervalent species. These are best portrayed in MO language (see Section 7.4) translated into VB terminology, they correspond to polar (or ionic) structures, e.g. ... 

Chemical bonds and population analysis Most metals of interest in the context of polymer-based electronic devices form some kind of chemical bond to the polymer upon interaction with a polymer surface. Population analysis, based on the electronic structure, is used to determine the character of this bond. According to the commonly used chemical terminology, bonds are classified as ionic if the bonded atoms are oppositely charged and held together by the attractive Coulomb force, and covalent if the two atoms are neutral but share the same pair of electrons. In the latter case, much of the electron density is located between the bonded atoms whereas for the ionic bond the charge density is concentrated at the atomic sites. 

Unlike classical molecular structures, interlocked molecules consist of two or more separate components which are not connected by chemical (i.e. covalent) bonds. These structures are true molecules and not a supramolecular species, as each component is intrinsically linked to the other, resulting in a mechanical bond which prevents dissociation without cleavage of one or more covalent bonds. It should be noted that the mechanical bond is a relatively new terminology and at this point has limited usage in chemical literature relative to more well-established bonds, such as covalent, hydrogen, or ionic bonds. 

First a few words on the terminology. When 0 states form dimers their signal disappears from the EPR spectrum because of spin pairing. In a predominantly ionic host matrix... 

The constant c provides a parameter to vary during optimization. They, in effect, used molecular orbital (MO)s in the wave function, but this terminology is not usually used in the current context. The introduction of this sort of orbital provides the same effect as ionic terms in the more traditional treatment. The next two sections give modem extensions of this method. 

---