antimony

A metallic element having four allotropic forms, the most common of which is a hard, extremely brittle, lustrous, silver-white, crystalline material. It is used in a wide variety of alloys, especially with lead in battery plates, and in the manufacture of flame-proofing compounds, paint, semiconductor devices, and ceramic products. Atomic number 51; atomic weight 121.76; melting point 630.5°C; boiling point 1,380°C; specific gravity 6.691; valence 3, 5. See Table at element.