A soft, light, extremely malleable silver-white element that is an alkali metal, reacts violently with water, is naturally abundant in combined forms, especially in common salt, and is used in the production of a wide variety of industrially important compounds. Sodium ions are essential to numerous biological processes in animals. Atomic number 11; atomic weight 22.9898; melting point 97.80°C; boiling point 883°C; specific gravity 0.971 (20°C); valence 1. See Periodic Table.