Nonmetals overview

This section presents a brief overview of a few other compounds that have not been described in previous sections. Because it can function as a nonmetal, silicon forms sihcides with several metals. These materials are often considered as alloys in which the metal and silicon atoms surround each other in a pattern that may lead to unusual stoichiometry. Examples of this type are Mo3Si and TiSi2. In some sihcides, the Si-Si distance is about 235 pm, a distance that is quite close to the value of 234 pm found in the diamond-type structure of elemental silicon. This indicates that the structure contains Si22-, and CaSi2 is a compound of this type. This compound is analogous to calcium carbide, CaC2 (actually an acetylide that contains C22- ions (see Chapter 10)). 

Chapter 1 An Overview of Metals and Selected Nonmetals in Biology 3... 

The first two elements of Group 5A(15), gaseous noiunetallic nitrogen (N) and solid nonmetallic phosphorus (P), play major roles in both nature and industry. Below these nonmetals are two metalloids, arsenic (As) and antimony (Sb), followed by the metal bismuth (Bi), and the recently synthesized element 115. The Group 5A(15) Family Portrait on the next page provides an overview. 

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