Valency monovalent

The usual valence of indium is three, although monovalent and bivalent compounds of indium with oxygen, halogens, and Group 15 (VA) and 16 (VIA) elements ate well known. The lower valence compounds tend to disproportionate into the trivalent compound and indium metal the trivalent compounds ate stable. 

Slater, J. C., Phys. Rev. 35, 509, "Cohesion in monovalent metals." Connection between molecular-orbital and valence-... 

The type of catalyst influences the rate and reaction mechanism. Reactions catalyzed with both monovalent and divalent metal hydroxides, KOH, NaOH, LiOH and Ba(OH)2, Ca(OH)2, and Mg(OH)2, showed that both valence and ionic radius of hydrated cations affect the formation rate and final concentrations of various reaction intermediates and products.61 For the same valence, a linear relationship was observed between the formaldehyde disappearance rate and ionic radius of hydrated cations where larger cation radii gave rise to higher rate constants. In addition, irrespective of the ionic radii, divalent cations lead to faster formaldehyde disappearance rates titan monovalent cations. For the proposed mechanism where an intermediate chelate participates in the reaction (Fig. 7.30), an increase in positive charge density in smaller cations was suggested to improve the stability of the chelate complex and, therefore, decrease the rate of the reaction. The radii and valence also affect the formation and disappearance of various hydrox-ymethylated phenolic compounds which dictate the composition of final products. 

The effects of ion valence and polyelectrolyte charge density showed that at very low ionic strength found that when the counterion valence of added salt changes from monovalent (NaCl) to divalent (MgS04), the reduced viscosity decreases by a factor of about 4.5. If La(N03)3 is used, the reduced viscosity will be further decreased although not drastically. As for polyelectrolyte charge density, the intrinsic viscosity was found to increase with it because of an enhanced intrachain electrostatic repulsion (Antonietti et al. 1997). 

Imai (1961) has observed that multivalent counterions are more strongly bound than are monovalent ones. This phenomenon can be demonstrated theoretically by considering equilibrium conditions for two counterions with valencies z and (Zj > z and degrees of dissociation and P -For a cylindrical model the equilibrium equations are... 

The selective binding of cations is not as sensitive to size as to valence. The value of Q for the condensation of counterions of the same valence is unaffected. In the case of monovalent cations, the dissociation of all counterions is complete at infinite dilution, when 2 1 When Q the... 

A comparison of this equation with the equations provided above points out that lead (IV) oxide is clearly not a base. The nature of metallic hydroxides varies according to the position of the metal in the reactivity series, as given in Table 6.3. Metallic hydroxides are electrovalent compounds, composed of metal ions, which are positively charged, and hydroxy ions, OTT. The number of OTT ions associated with one metallic ion is equal to the valency of the metal, e.g., Na+OH sodium is monovalent Ca2+(OTT)2 calcium is divalent. The metallic hydroxides form a very important series of compounds, and are known to have many uses both in the laboratory and in industry. 

Soils containing polyvalent cations having high valence and high electrolyte concentration have a high conductivity, whereas the soils containing monovalent cations, such as sodium, have a low k. Distilled water at the extreme end of the spectrum is free of electrolytes. In the Gouy-Chapman equation, the electrolyte concentration na would be 0. The denominator, therefore, would go to 0 and the T value to infinity. 

The two-step charge transfer [cf. Eqs. (7) and (8)] with formation of a significant amount of monovalent aluminum ion is indicated by experimental evidence. As early as 1857, Wholer and Buff discovered that aluminum dissolves with a current efficiency larger than 100% if calculated on the basis of three electrons per atom.22 The anomalous overall valency (between 1 and 3) is likely to result from some monovalent ions going away from the M/O interface, before they are further oxidized electrochemically, and reacting chemically with water further away in the oxide or at the O/S interface.23,24 If such a mechanism was operative with activation-controlled kinetics,25 the current-potential relationship should be given by the Butler-Volmer equation... 

The report of the first zinc compound with a Zn-Zn core elicited a number of critical comments on the structure and bonding of decamethyldizincocene, and the interpretation of the results.236,237 None of the authors of these commentaries questioned the data or their interpretation. Parkin, however, has pointed out that the formal oxidation state of +1 for zinc in this compound is merely due to the convention that metals are assigned an oxidation state of 0 when they form bonds with like atoms.237 If the conventional definition of valence, namely the capacity of atoms to form bonds to other atoms is used, then the zinc atoms in decamethyldizincocene are not monovalent, but divalent. The synthesis of a paramagnetic organozinc compound in which zinc uses only one of its two 4s electrons will remain an interesting challenge to many synthetic organometallic chemists. 

This value corresponded to an eightfold enhancement as compared to corresponding monovalent lactoside derivative under the same conditions. However, an increase in the branching of the dendron (namely valency) provided only a modest increase in the potency of the ligand, corresponding to a rather constant relative potency per lactose, regardless of the number of peripheral epitopes. 

For example, atoms of both the alkaline-earth family (ZAval = 2) and the chalcogen family (ZAval = 6) correspond to FAemp = 2, and their stoichiometric proportionality (or coordination number) to monovalent atoms is therefore commonly two (AH2, ALi2, AF2, etc.). It is a remarkable and characteristic feature of chemical periodicity that the empirical valency FAemp applies both to covalent and to ionic limits of bonding, so that, e.g., the monovalency of lithium (Vuemp = 1) correctly predicts the stoichiometry and coordination number of covalent (e.g., Li2), polar covalent (e.g., LiH), and extreme ionic (e.g., LiF) molecules. Following Musher,132 we can therefore describe hypervalency as referring to cases in which the apparent valency FA exceeds the normal empirical valency (3.184),... 

If we now assume, following Lewis, that each monovalent bond coordination is associated with an electron pair, we can write the total number (ebf) of valence bond-pair electrons as... 

Substitution of an ion with one valence by another with a different valence, aliovalent substitution, will create a charged defect. For example, a divalent ion such as Ca2+ substituted for a monovalent Na+ on a sodium site in NaCl gives a local electronic charge augmented by one extra positive charge ... 

It is important that the copper is in the monovalent state and incorporated into the silver hahde crystals as an impurity. Because the Cu+ has the same valence as the Ag+, some Cu+ will replace Ag+ in the AgX crystal, to form a dilute solid solution Cu Agi- X (Fig. 2.6d). The defects in this material are substitutional CuAg point defects and cation Frenkel defects. These crystallites are precipitated in the complete absence of light, after which a finished glass blank will look clear because the silver hahde grains are so small that they do not scatter light. 

Experimental data on the compressibilities of solid salts appear to be consistent with the general form of the core repulsion part of the pair potential (1 /i)/(r/rf) even for the exponential form.8 Although for simplicity the equations are written for monovalent ions in a vacuum, they may easily be extended to other valence types and to ions contained in a dielectric. 

Matus89 claims that the activation of PG by various ions increases with the valence of the cation with an especially great increase in activity from the monovalent sodium to the bivalent calcium ions ... 

Salt activation falls into two classes with respect to the valency of the cation component. With divalent cations and at pH 6, maximum activation is produced at about 0.03 M concentration. At higher concentrations with the same pH, suppression of activity occurs. Monovalent cations in general produce maximum activation at pH 6 in 0.10 M concentration and do. not suppress activity below molarities of 1.0. Maximum activity is obtained at a lower pH and lower concentration of divalent cations than monovalent. The maximum activity obtained at the optimum salt concentration for a given pH value is, within experi-... 

Additionally, the incomplete oxidation of fuel generates weak organic acid anions. Furthermore, there is loss of base in the faeces each day which, in effect, leaves the body with an excess of protons to be excreted. In total, about 70 milliequivalents (mEq) of acid require excretion each day. Note mEq is used to quantify the acid load because this takes account of the valency of the ion 1 mmol of sulfate, S04, for example, is 2 mEq of negative charge, requiring 2 mEq of protons for neutralization, but for monovalent ions, such as protons or bicarbonate, 1 mEq= 1 mmol. ... 

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