Electrovalent bonding

Modern bonding theory treats the electron pairing in terms of the interaction of electron (atomic) orbitals and describes the covalent bond in terms of both bonding and anti-bonding molecular orbitals. See also coordinate bond electrovalent bond polar bond. 

Primary bonds include electrovalent, covalent, and metallic bonds. Electrovalent or het-eropolar bonds may be a factor in protein adhesives. Covalent or homopolar bonds play a part in some finishing treatments for fiber glass. The metallic bond is formed by welding, soldering, and brazing. The metals and alloys involved are essentially high temperature thermoplastic adhesives, but are outside the scope of this volume. 

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. 

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)). 

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,... 

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,... 

COORDINATION COMPOUNDS. One of a number of types of complex compounds, usually derived by addition from simpler inorganic substances. Coordination compounds are essentially compounds to which atoms or groups have been added beyond the number possible on the basis of electrovalent linkages, or the usual covalent linkages, to which each of the two atoms linked donates one electron (o Form the duplet. The coordinate groups are linked to the atoms of the compound usually by coordinate valences, in which both the electrons in the bond are furnished by the linked atom of the coordinated group. The amines and complex cyanides are representative of coordination compounds. 

The process of the shifting of an electron from one electrical field to another, as in the formation of an electrovalent bond, in which an electron moving in an orbit about one atom shifts to move in an orbit around the two bonded atoms. 

OXIDATION NUMBER. In its original and restrictive sense, the number of electrons which must be added to a cation to neutralize the charge. The concept has been extended to anions by assignments of negative oxidation numbers. Moreover, it has been further extended, first to all atoms or radicals joined by electrovalent bonds, and then to covalent compounds in which the shared electrons are distributed equally. For the broadest use of the concept, the expression oxidation state is often used. 

The forces involved in chemistry are essentially electrostatic. They are variants on the Coulomb force. We can distinguish two orders primary forces and secondary forces. Primary forces are those which hold the atoms together in molecules, and the oppositely charged ions in crystalline salts. Respectively, they are known as covalency and electrovalency (or, sometimes, the ionic force). The latter is directly electrostatic, the mutual attraction between Na+ and Cl" in common salt, for example. The former is usually figured as the sharing of an electron-pair between two atoms— Cl-Cl in the chlorine molecule, where the bond stands for a shared pair of electrons. We need quantum mechanics to understand why, in certain circumstances, electron density builds up in the region between the two chlorine atoms. Granted that it does so, we can explain the covalent bond as due to a resultant electrostatic effect. 

The ionic or electrovalent bond is a third kind of linkage. When EN between the binding atoms exceeds the value of 1.7, there is hardly question of common electron pairs. In that case the valence electrons of the atom with the smallest EN-value are almost entirely transferred to the other atom with the largest EN-value. One atom loses one or more electrons and becomes a positively charged ion, whereas the other gains one or more electrons and becomes a negatively charged... 

Ionic (electrovalent) bond A strong electrostatic force of attraction between oppositely charged ions. 

There is no doubt that Pearson did not suggest something entirely new, as we have already seen, but he generalized the concepts derived from the mass-action law (formation constants and Bransted acidity) in a variety of new ways. Many chemists have felt that hard-hard interactions are a new name for electrovalent (ionic) bonding and soft-soft interactions for covalent bonding37. This is also a part of the truth, but other aspects are far more sophisticated and deserve detailed discussion. Other chemists sharply criticize the short and colloquial words hard and soft . In the writer s... 

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