Other Normal-valence Compounds of the Nonmetals

The halogens form covalent compounds with most of the nonmetallic elements (including each other) and the metalloids. These compounds are usually molecular substances, with the relatively low melting points and boiling points characteristic of substances with small forces of inter-molecular attraction. 

An example of a compound involving a covalent bond between a halogen and a nonmetal is chloroform, CHClg. In this molecule the carbon atom is attached by single covalent bonds to one hydrogen atom and three chlorine atoms. Chloroform is a colorless liquid, with a characteristic sweetish odor, b.p. 61°C, density 1.498 g ml. Chloroform is only slightly soluble in water, but it dissolves readily in alcohol, ether, and carbon tetrachloride. 

The halides of carbon and its congeners are tetrahedral (sp bond orbitals). Those of nitrogen and oxygen and their congeners have bond angles near 100°, corresponding to p bond orbitals with a small amount of s character. 

Many of these substances react readily with water, to form a hydride of one element and a hydroxide of the other  

In general, in a reaction of this sort, called hydrolysis, the more electronegative element combines with hydrogen, and the less electronegative element combines with the hydroxide group. This rule is seen to be followed in the above examples. 

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