Silicon, atomic no. 14, symbol Si, weight at 28.0855, is one of man's most useful elements. It makes up 25.7% of the earth's crust, by weight, and is the second most abundant element, being exceeded only by oxygen.
Silica, as sand, is a principal ingredient of glass, one of the most inexpensive of materials with excellent mechanical, optical, thermal, and electrical properties.
Ultra high purity silicon can be doped with boron, gallium, phosphorus, or arsenic to produce silicon for use in transistors, solar cells, rectifiers, and other solid-state devices which are used extensively in the electronics and space-age industries.
Hydrogenated amorphous silicon has shown promise in producing economical cells for converting solar energy into electricity.
Silcones are important products of silicon. They range from liquids to hard, glasslike solids with many useful properties.