Ionic compounds defined

We learned to write formulas of ionic compounds in Chaps. 5 and 6. We balanced the charges to determine the number of each ion to use in the formula. We could not do the same thing for atoms of elements in covalent compounds, because in these compounds the atoms do not have charges. In order to overcome this difficulty, we define oxidation numbers, also called oxidation states. 

When applied to the motion of ions in a crystal, the term drift applies to motion of ions under the influence of an electric field. Although movement of electrons in conduction bands determines conductivity in metals, in ionic compounds it is the motion of ions that determines the electrical condu-ctivity. There are no free or mobile electrons in ionic crystals. The mobility of an ion, ji, is defined as the velocity of the ion in an electric field of unit strength. Intuitively, it seems that the mobility of the ion in a crystal should be related to the diffusion coefficient. This is, in fact, the case, and the relationship is... 

The answers are 31-b, 32-a, 33-d (Katzung, pp 4—7.) The absorption, distribution, and elimination of drugs require that they cross various cellular membranes The descriptions that are given in the question define the various transport mechanisms. The most common method by which ionic compounds of low molecular weight (100 to 200) enter cells is via membrane channels. The degree to which such filtration occurs varies from cell type to cell type because their pore sizes differ. 

The equilibrium between an ionic compound like that of formula (1) and an aqueous solution can be described by a solubility product defined by ... 

The energy equation 3-3 may be used to define the ion energy level of ionic compound molecules. Fmthermore, this energy equation may also be used to define the ion energy level in covalently bonded compoimd molecules, though the physical meaning of the ion level in covalent compounds is a matter of discussion. 

In even more disadvantageous circumstances, the thermal decomposition does not yield a single defined product, but a complex mixture that results in almost useless spectra, e.g., in case of highly polar natural products such as saccharides, nucleotides, and peptides or in case of ionic compounds such as organic salts or metal complexes. 

Acids react with HgO to produce corresponding Hg(II) compounds. Two classes of Hg(II) compounds maybe defined covalent and ionic. The covalent compounds HgCl2, HgBr2, HgD, and Hg(CN)2 go into HOH solution chiefly as undissociated molecules, which undergo little hydrolysis. The ionic compounds which include HgF2, Hg(N03)2, HgS04, and Hg(C104)2 go into... 

Many different types of reversible reactions exist in chemistry, and for each of these an equilibrium constant can be defined. The basic principles of this chapter apply to all equilibrium constants. The different types of equilibrium are generally denoted using an appropriate subscript. The equilibrium constant for general solution reactions is signified as or K, where the c indicates equilibrium concentrations are used in the law of mass action. When reactions involve gases, partial pressures are often used instead of concentrations, and the equilibrium constant is reported as (p indicates that the constant is based on partial pressures). and are used for equilibria associated with acids and bases, respectively. The equilibrium of water with the hydrogen and hydroxide ions is expressed as K. The equilibrium constant used with the solubility of ionic compounds is K p. Several of these different K expres-... 

Ionic Size. The size of an ion is a somewhat hazy concept because the modern notion of atoms pictures the electron distribution to extend to infinity. Nevertheless, it is true that there are definite distances established between the centers of atoms in a compound. It is thus natural to attempt to conceive of the distance between, say, Na+ and CT in solid sodium chloride as being made up as a sum of two contributions, one from the negative ion and the other the positive ion. This amounts to defining the sizes of ions in such a manner that in each ionic compound the sum of the ionic radii equals the observed interionic distance at equilibrium. 

Acid-base neutralization reactions are processes in which an acid reacts with a base to yield water plus an ionic compound called a salt. You might recall from Section 2.9 that we defined acids as compounds that produce H+ ions when dissolved in water and bases as compounds that produce OH- ions when dissolved in water. Thus, the driving force behind a neutralization reaction is the production of the stable covalent water molecule by removal of H + and OH- ions from solution. The reaction between hydrochloric acid and aqueous sodium hydroxide to yield water plus aqueous sodium chloride is a typical example ... 

When solutions of soluble ionic compounds are mixed, an insoluble compound will precipitate if the ion product (IP) for the insoluble compound exceeds its fCsp. The IP is defined in the same way as /equilibrium concentrations. Certain metal cations can be separated by selective precipitation of metal sulfides. Selective precipitation is important in qualitative analysis, a procedure for identifying the ions present in an unknown solution. 

Another point which needs to be clarified from the start is the nomenclature of metalated silanes We will frequently use the term silyl anion in this chapter when we talk about metalated silanes. Although the term anion defines, literally taken, an ionic compound, this expression, when used by us, does not necessarily imply that the compound in question is of ionic nature, but covers, as well, in analogy to the use of the term carbanion , silicon compounds with a polarized covalent silicon-metal bond. 

The lattice energy U of an ionic compound is defined as the energy required to convert one mole of crystalline solid into its component cations and anions in their thermodynamic standard states (non-interacting gaseous ions at standard temperature and pressure). It can be calculated using either the Born-Land6 equation... 

The relationship between cubic close-packed (ccp) structures and ionic compounds of type B1 is obvious. Interstitial sites with respect to metal positions are at fractional coordinates of the type 00 and equivalent to the ionic sites in Bl. The Madelung constant of Al type metals with interstitially localized free electrons is therefore the same as that of rocksalt structures. It is noted that the interstitial sites define the same face-centred lattice as the metal ions. 

In section 3.2, you learned about the strong bonds that hold ions in clearly-defined lattice patterns. You learned that these bonds are responsible for the properties of ionic compounds. You also learned how to describe the properties of compounds that are made up of molecules with covalent bonds. In this section, you discovered that the properties of compounds with polar covalent bonds depend on their shape. The following Concept Organizer summarizes some of the properties of covalent compounds that are made up of polar and non-polar molecules. 

Manganese(II) compounds are quite labile the metal shows distinct class (a) character 7 and its ionic radius (defined by the M—H20 distances in Table 1) is large compared with the other first row transition metals. These lead to distinct parallels with magnesium(II) rather than the latter, although there are also significant parallels with octahedral high spin nickel(II). 

For metal hydride clusters, much less is known about electronic and geometrical size effects, except for very small clusters that can be relatively easily traced with computational methods. Results on other ionic compounds, such as ZnS clusters, indicate less well defined size effects, and only for small cluster sizes [11]. As the size dependence will be clearly different than for metal clusters, potentially there is a large influence of size on the stability differences between small hydride and the corresponding metal clusters. However, the practical impact of these effects is probably limited, as in the bulk experimental preparation of light metal (hydride) clusters, generally, polydisperse samples are obtained, and hence pronounced effects of... 

One of the defining characteristics of single-replacement and combustion reactions is that they always involve the transfer of electrons from one atom to another. So do many, but not all, synthesis and decomposition reactions. For example, you studied the synthesis reaction in which sodium and chlorine react to form the ionic compound sodium chloride. 

A linear relationship has been demonstrated by Clayden and Pugh (1998) between the quadrupole coupling constant Xq and the ionic radius r (in nm) of the M ions in the small group of sodium metal(IV) phosphates NaM2(P04)3 where M = Sn, Ge, Ti and Zr. The two resolvable Na sites of NaSn2(P04)3 straddle the line for these compounds, defined by ... 

---