Covalent compounds unpaired electrons

G for gallium. These values (see also in the next section) are consistent with the unpaired electron residing in a Ti-orbital. The stability of these compounds was attributed to the large size and electronic properties of the Si(f-Bu)3 substituents [26-28]. Computational data for the aluminum compound indicate an Al—Al distance of 2.537 A and a wide Al—Al-Si angle of 174.90° [26]. The longer distance for the aluminum species is a result of the larger covalent radius for this metal [18]. 

The two unpaired valence electrons of oxygen pair with the unpaired valence electrons of two hydrogen atoms to form the covalent compound water. 

In summary, it is noted that multiple bonding between the heavier Group 14 elements E (Ge, Sn, Pb) differs in nature in comparison with the conventional a and 7T covalent bonds in alkenes and alkynes. In an E=Ebond, both components are of the donor-acceptor type, and a formal E=E bond involves two donor-acceptor components plus a p-p n bond. There is also the complication that the bond order may be lowered when each E atom bears an unpaired electron or a lone pair. The simple bonding models provide a reasonable rationale for the marked difference in molecular geometries, as well as the gradation of bond properties in formally single, double and triple bonds, in compounds of carbon versus those of its heavier congeners. 

In very nearly all of its covalent compounds, carbon forms four bonds. The carbon atom (configuration is Is2 2s2 2p2), however, has only two unpaired electrons in its ground state and by a process of reasoning similar to that in the preceding paragraph, carbon would be expected to form only two covalent bonds. Confronted with this inconsistency, one is tempted to look for ways in which the carbon configuration can be modified to give four unpaired electrons. Suppose, for instance that the... 

Free radicals may also be formed by (a) homolysis of covalent bonds, (b) addition of an electron to a neutral atom, or (c) loss of a single electron from a neutral atom. These radicals, especially if they are of low molecular weight, are usually extremely reactive hence, they are short-lived. Since they have an unpaired electron, they are highly electrophilic (i.e., electron loving ) and attack sites of increased electron density, as in compounds with nitrogen atoms (e.g., proteins, amino acids, DNA, RNA) and carbon-carbon double bonds (i.e., polyuunsaturated fatty acids and phospholipids which make up bilipid cell membranes). 

It is important to know whether molecules being released in the lower atmosphere can reach the stratosphere and affect the amount of ozone in it. Certain types of air pollution give rise to radicals that catalyze ozone depletion. A radical is a chemical species that contains an odd (unpaired) electron, and it is usually formed by the rupture of a covalent bond to form a pair of neutral species. One pressing concern involves chlorofluorocarbons (CFCs)—compounds of chlorine, fluorine, and carbon used as refrigerants and as propellants in some aerosol sprays. CFCs are nonreactive at sea level but can photodissociate in the stratosphere ... 

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