Electrovalency

The electrovalency ( ) of an atom is the charge on the ion that it forms in units of e. This is determined by measuring the quantity of electricity that is required to discharge the ion in electrolysis, or from the formula of binary compounds knowing the charge on the other ion present. Care is needed to establish the molecular formula of the ion. For example, mercury forms two series of compounds, exemplified by the nitrates (containing NOs ions)  

Most members of the series are weak electrolytes, but the nitrates are good conductors in aqueous solution, and from their composition, might be supposed to contain Hg and Hg ions respectively. However, a study of the formation of (1) by shaking a solution of (II) with mercury shows that the equilibrium is less well represented by the equation 

Show that the following results conform better to equation (2) than to equation 

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The word is also used to denote a unit in a solid crystal of an electrovalent compound such as NaCl in which each Na is electrically attracted by the surrounding six Cl" and each Cl" is electrically attracted by the surrounding six Na. The structure of such crystals is termed ionic to indicate that the crystal is not an aggregate of independent molecules. 

The electrovalent bond is formed by electrostatic attraction between oppositely charged ions. Thus Na, with one outer electron, loses this electron to achieve the noble gas Ne structure, while Cl with seven outer electrons, gains one electron to achieve the Ar structure. 

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. 

An explanation of valency on the basis of modem views of atomic structure. It is assumed that certain arrangements of outer electrons in atoms ( octets or outer shells of eight electrons) are stable and tend to be formed by the transfer or sharing of electrons between atoms. See Covalency and Electrovalency. 

The link which holds the atoms together in a molecule. See Covalency and Electrovalency. Valency Electrons... 

HB-5) unusually high cationic character of central atom B and anionic character of terminal atoms A and C, as reflected in natural atomic charges Qa, Qb, Qc), ionic bond orders (6AB(ion) and Aiic<1011)), and electrovalencies (TA(lon), IV1011 . Vc(l0n)). 

Studies in Electrovalency," 822831 and 18661867 James Allan, Albert E. Oxford, Robert Robinson and John C. Smith, "The Relative Directive Powers," 401411 E. H.Ingold and C. K. Ingold, "The Nature of the Alternating Effect," 13101328. 

ELECTROSTATIO BOND ELECTROSTATIO SUREAOE POTENTIAL ELECTROSTRIOTION ELECTROTAXIS ELECTROVALENT BOND ELEMENTARY OHARGE ELEMENTARY REACTION Elementary reaction stoichiometry, MOLECULARITY CHEMICAL KINETICS UNIMOLECULAR BIMOLECULAR TRANSITION-STATE THEORY ELEMENTARY REACTION Element effect,... 

On the whole, the thermod3mamic functions found for the stepwise formation of complexes in aqueous solution agree very well with the models proposed for complexes of different character. Thus for interactions between hard acceptors and hard donors, postulated to be mainly electrovalent, the expected stepwise decrease of ASn generally occnrs, often accompanied by a similarly expected decrease of AHn- With interactions between soft acceptors and soft donors, postulated to be mainly covalent, virtually constant values of AHn from step to step are often found, while in other cases values of AHn becomes step by step less exothermic. Both modes of behaviour are compatible with the current model. 

Complexes, see also specific type in solution, structures, see X-ray diffraction n-Complexes, 4 178-184 Complex formation constant, outersphere, 43 46, 55 electrovalent interaction in, 3 269-270 Compressibility coefficient of activation, 42 9 Comproportionation constants, class II mixed-valence complexes, 41 290-292 Comproportionation equilibrium, 41 280-281 Compton effect, 3 172 Conantokins, calcium binding, 46 470-471 Concanavalin A, 36 61, 46 308 Concensus motif, 47 451 Concentration-proportional titrations of poly-metalates, 19 250, 251, 254 Condensation... 

Elecfrothermal atomization atomic absorption spectrometry, lithium, 36 54 Electrovalent compounds, high oxidation states of, stability, 5 10-11... 

The coordination number of chloride can be rather high in many sohds. Thus, iV = 8 in CsCl, iV = 6 in NaCl and the perovskite CsNiCla, iV=4 in CuCl, W = 3 in NiCl2 etc. It might be argued that the values of N higher than four correspond to exclusively electrovalent bonding. This is not an easy position to defend the NaCl-type MgS, BaS, LaN,... 

The process of Cd UPD on polycrystalline Pt was investigated by Machado et al. [278-280], and adsorption electrovalence of Cd adions was found to be close to 0.5 [280]. The detailed mechanism was also studied, using electrochemical and EQCM measurements [281, 282]. The formal partial charge number was found to vary between 1 and 2, for higher and lower potentials, respectively. A mechanism involving two adsorption sites and the presence of Cd+ adsorbed ions was proposed. 

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