Electronegativity and Chemical Properties

An obvious use of an electronegativity scale is to predict the direction of electrical polarity of a covalent bond with ionic character. Table 2.2 tells us that the C—H bond in alkanes (C H2n+2) is polar in the same sense as the O—H bonds in water, although to a much lesser degree  

On the other hand, the polarity of the Si—H bond in silanes (silicon analogs of alkanes) is reversed  

the hydrogens in silanes (or organosilanes, if R is an organic group) behave more like hydride ions (H ) than like protons (H+). Whereas tri-phenylmethane (R = CeHs) is unreactive toward water, triphenylsilane hydrolyzes (reacts with water) to give triphenylsilanol [(C6H5)3Si—OH] and hydrogen gas (cf. H + H2O OH + H2)  

Similarly, very few true ionic hydrides, borides, nitrides, and carbides exist (see Chapter 5). 

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