Silicon

1. Symbol Si. A nonmetallic element occurring extensively in the earth's crust in silica and silicates, having both an amorphous and a crystalline allotrope, and used doped or in combination with other materials in glass, semiconducting devices, concrete, brick, refractories, pottery, and silicones. Atomic number 14; atomic weight 28.086; melting point 1,410 degrees C; boiling point 2,355degrees C; specific gravity 2.33; valence 4. Silicon is most widely distributed in dusts and sands.