Ion charged species

Ion Charged species. See also Anion Cation, 3546q... 

Radical ions - charged species with unpaired electrons - are easily generated by a number of methods that are discussed in more detail below. Their properties have been characterized by several spectroscopic techniques, and their structures and spin density contributions have been the subject of molecular orbital calculations at different levels of sophistication. The behaviour of radical ions in rearrangement and isomerization reactions as well as in bond-cleavage reactions has been extensively studied [for recent reviews see Refs. 11-13 and references cited therein]. Useful synthetic applications, such as the radical-cation-catalyzed cycloaddition [14-20] or the anfi-Markovnikov addition of nucleophiles to alkenyl radical cations [21-25], have been well documented. In... 

So far in this chapter we have discussed only binary ionic compounds, which contain ions derived from single atoms. However, many compounds contain polyatomic ions charged species composed of several atoms. For example, ammonium nitrate contains the and N03 ions. 

So far in this chapter we have discussed only binary ionic compounds, which contain ions derived from single atoms. However, many compounds contain polyatomic ions charged species composed of several atoms. For example, ammonium nitrate contains the NH4- and NOs ions. These ions with their opposite charges attract each other in the same way as do the simple ions in binary ionic compounds. However, the individual polyatomic ions are held together by covalent bonds, with all of the atoms behaving as a unit. For example, in the ammonium ion, NH4-, there are four N—H covalent bonds. Likewise the nitrate ion, NOs , contains three covalent N—O bonds. Thus, although ammonium nitrate is an ionic compound because it contains the NH4-and NO3" ions, it also contains covalent bonds in the individual polyatomic ions. When ammonium nitrate is dissolved in water, it behaves as a strong electrolyte like the binary ionic compounds sodium chloride and potassium bromide. As we saw in Chapter 7, this occurs because when an ionic solid dissolves, the ions are freed to move independently and can conduct an elearic current. 

Ionization (Section 9.14) Conversion of neutral molecules to ions (charged species). 

Migration is the movement of ions due to a potential gradient. In an electrochemical cell the external electric field at the electrode/solution interface due to the drop in electrical potential between the two phases exerts an electrostatic force on the charged species present in the interfacial region, thus inducing movement of ions to or from the electrode. The magnitude is proportional to the concentration of the ion, the electric field and the ionic mobility. 

Atoms combine with one another to give compounds having properties different from the atoms they contain The attractive force between atoms m a compound is a chemical bond One type of chemical bond called an ionic bond, is the force of attraction between oppositely charged species (ions) (Figure 1 4) Ions that are positively charged are referred to as cations, those that are negatively charged are anions... 

Capillary zone electrophoresis provides effective separations of any charged species, including inorganic anions and cations, organic acids and amines, and large biomolecules such as proteins. For example, CZE has been used to separate a mixture of 36 inorganic and organic ions in less than 3 minutes.Neutral species, of course, cannot be separated. 

Thus two electrons exit the reaction zone, leaving a positively charged species (M ) called an ion (in this case, a molecular ion). Strictly, M" is a radical-cation. This electron/molecule interaction (or collision) was once called electron impact (also El), although no impact actually occurs. 

A further consequence of the high temperatures is that much of the sample is simply evaporated without producing isolated positive ions. There is a competition between formation of positive ions and the evaporation of neutral particles. Since the mass spectrometer examines only isolated charged species, it is important for maximum sensitivity that the ratio of positive ions to neutrals be as large as possible. Equation 7.1 governing this ratio is given here. 

The kinetic or translational energy of the ions is equal to the work done on moving the charged species through the potential, V, i.e., l/2mjVi = zV and l/2m2V2 = zV, where z is the charge on the ions and Vj, V2 are their final velocities. From this, we obtain Equations 33.1 and 33.2. 

Since a discharge is characterized by having a substantial population of charged species (electrons and ions), it responds to an applied electromagnetic field. The applied field moves electrons in one direction and positive ions in the opposite direction, in accordance with Maxwell s laws. 

Plasma consists of a gaseous mixture of neutral species, ions, and electrons. The charged species are in approximately equal concentrations. 

Magnetic/electric-sector instruments are used to manipulate ion beams by making use of the deflection of charged species (ions) in magnetic or electric fields. 

Positive or negative ions (electrically charged species) from a source are injected along the central axis of the quadrupole assembly. 

Ion/neutral reaction. Interaction of a charged species with a neutral reactant to produce either chemically different species or changes in the internal energy of one or both of the reactants. 

The dielectric constant is a measure of the ease with which charged species in a material can be displaced to form dipoles. There are four primary mechanisms of polarization in glasses (13) electronic, atomic, orientational, and interfacial polarization. Electronic polarization arises from the displacement of electron clouds and is important at optical (ultraviolet) frequencies. At optical frequencies, the dielectric constant of a glass is related to the refractive index k =. Atomic polarization occurs at infrared frequencies and involves the displacement of positive and negative ions. 

These three terms represent contributions to the flux from migration, diffusion, and convection, respectively. The bulk fluid velocity is determined from the equations of motion. Equation 25, with the convection term neglected, is frequently referred to as the Nemst-Planck equation. In systems containing charged species, ions experience a force from the electric field. This effect is called migration. The charge number of the ion is Eis Faraday s constant, is the ionic mobiUty, and O is the electric potential. The ionic mobiUty and the diffusion coefficient are related ... 

The charged species were in all cases found to concentrate at the surface of the liquid under vacuum conditions. Little surface separation of the anions and cations was observed. For the [PFg] and [BFJ ions, the cation ring was found to prefer a perpendicular orientation to the surface, with the nitrogen atoms closest to the surface. An increase in the alkyl chain length caused the cation to rotate so that the alkyl chain moved into the bulk liquid, away from the surface, forcing the methyl group closer to the surface. For halide ionic liquids, the data were less clear and the cation could be fitted to a number of orientations. 

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