silicon (Si) /sil″ikon/ [L, silex, flint] , a nonmetallic element, second to oxygen as the most abundant of the elements in the earth’s crust. Its atomic number is 14, and its atomic mass is 28.09. It occurs in nature as silicon dioxide and in silicates. The silicates are used as detergents, corrosion inhibitors, adhesives, and sealants. Elemental silicon is used in metallurgy and in transistors and other electronic components. About 60% of the rocks in the earth’s crust contain silicon, and silica dust is associated with many mining operations. Protracted inhalation of silica dust can cause silicosis, which increases the susceptibility to other pulmonary diseases.
