Electronegativity Electroneutrality principle

ELECTRON DENSITY CHARGE DENSITY ELECTRON DENSITY EUNCTION ELECTRON DONOR ELECTRONEGATIVITY ELECTRONEUTRALITY PRINCIPLE Electronic transitions,... 

The transfer of an electron to the iron atom is compatible with the electroneutrality principle. The electronegativity of iron is 1.8, leading to 12% ionic character of the iron-carbon bonds and to the satisfactory value +0.04 for the resultant charge on an iron atom that has accepted an electron and is forming nine bonds with carbon atoms. 

One classical example that apphes the electroneutrality principle is the electronic structure of carbon monoxide, a diatomic molecule with a very small dipole moment of 0.110 debye. The only electronic structure that satisfies the octet rule for CO is C=0 , a structure that corresponds to C and O, if the shared electron pairs are equally devided by the two atoms. Pauling showed that the electronegativity difference of 1.0 would correspond to about 22% partial ionic character for each bond, and to charges of and 0° +. A second possible electronic structure, C=O , does not complete the octet for carbon. The partial ionic character of the bonds corresponds to C0.44+ If these two structures contribute... 

This large amount of electron transfer is not incompatible with the electroneutrality principle. The electronegativity of aluminum is 1.5, and that of gold is 2.4. The difference corresponds to 18 percent ionic character of the Au—A1 bonds, which with valence 6.60 for gold would lead to the charge —1.19 on the gold atom. To restore it to neutrality 1.19 electrons would have to be transferred to two aluminum atoms. 

In apparent contradiction to the electroneutrality principle, there are many complexes in which the metal exists in a low oxidation state and yet is bonded to an element of fairly low electronegativity. Among the most prominent examples are the transition metal carbonyls, a large class of compounds in which the ligand (CO) is bound to the central metal through carbon. The source of stability in these complexes is the capacity of the carbon monoxide ligand to accept a back donation of electron density from the metal atom. Within valence bond theory, this process can be described in terms of resonance ... 

This amount of double-bond character is to be expected from consideration of the principle of electroneutrality (Sec. 8-2). The 30 percent partial ionic character of the Si—Cl bond that corresponds to the difference in electronegativity of the atoms would place the charge + 1.2 on the silicon atom in the SiCU molecule. This electric charge would be reduced to zero if each bond had 30 per cent double-bond character, or to +0.2 (a value approximating electroneutrality) if each bond had 25 percent double-bond character. This amount of doublebond character (and the same amount of partial ionic character for each bond) is given by resonance among the six equivalent structures of type B ... 

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