1. 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°C; boiling point 2,355°C; specific gravity 2.33; valence 4. see table at element.

1. A nonmetallic element (symbol si) with an atomic number of 14 and atomic weight of 28.0855.

1. A nonmetalic element analogous to carbon. it always occurs combined in nature, and is artificially obtained in the free state, usually as a dark brown amorphous powder, or as a dark crystalline substance with a meetallic luster. its oxide is silica, or common quartz, and in this form, or as silicates, it is, next to oxygen, the most abundant element of the earth's crust. silicon is characteristically the element of the mineral kingdom, as carbon is of the organic world. symbol si. atomic weight 28. called also silicium.

1. chemical symbol, si; atomic weight, 28. 19. A non-metallic element which is obtained in three allotropic forms—namely, amorphous, as a dull-brown powder soluble in alkali, which burns when ignited; graphitic, in crystalline leaves having a strong metallic luster and lead-gray color, insoluble in alkali and non-combustible; and crystalline, in octahedral needles having a red luster, and hardness a little less than that of the diamond.
2. elementary silicon can now he prepared in large qnantity by electrolysis, and in a fused condition. like its oxid, in cooling from a state of fusion it passes through a plastic stage in which it can be molded into special forms or drawn into threads.

1. a tetravalent nonmetallic element; next to oxygen it is the most abundant element in the earth's crust; occurs in clay and feldspar and granite and quartz and sand; used as a semiconductor in transistors