Compounds with the Nonmetals

The alkali-metal hydrides were described in Chapter 2. 

Others of the nonmetallic elements react with alkali metals to give binary compounds (typical examples are Na3As, Na2Se). These yield the corresponding hydrides (for example, AsH3 and H2Se) when treated with water. 

Many of the alkali-metal salts are among the most familiar of the laboratory reagents. Almost all of these are soluble, but Sidgwick has used a simple generalization as to the order of their solubilities for anions 

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Hydrides, nitride and carbides are known for some of the elements. Some have simple stoichiometry and structure, such as TiN and TiC with the rocksalt structure. Many are nonstoichiometric with metallic properties, and some can be regarded as interstitial compounds with the nonmetal atom occupying sites between metallic atoms in the normal elemental structure. 

Metal oxides belong to a class of widely used catalysts. They exhibit acidic or basic properties, which make them appropriate systems to be used as supports for highly dispersed metal catalysts or as precursors of a metal phase or sulfide, chloride, etc. Simple metal oxides range from essentially ionic compounds with the electropositive elements to covalent compounds with the nonmetals. However, taking into account the large variety of metal oxides, the principal objective of this book is to examine only metal oxides that are more attractive from the catalytic point of view, and most specifically transition metal oxides (TMO). In particular, TMO usually exhibit nonstoichiometry as a consequence of the presence of defective structures. The interaction of TMO with surfaces of the appropriate carriers develop monolayer structures of these oxides. The crystal and electronic structure, stoichiometry and composition, redox properties, acid-base character and cation valence sates are major ingredients of the chemistry investigated in the first part of the book. New approaches to the preparation of ordered TMO with extended structure of texturally well defined systems are also included. 

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