Sodium
Sodium, a soft, silvery white metallic element. Sodium is the sixth most abundant element on earth, but it is always found combined with other elements. It is an excellent conductor of heat and electricity. Sodium is lightweight and at ordinary temperatures has a soft, rather waxlike consistency. It is malleable (can be hammered or rolled into a thin sheet) and ductile (can be drawn into wire).
Sodium reacts vigorously with water to form hydrogen and sodium hydroxide. This reaction produces enough heat to melt the sodium, which skitters on the water's surface. In some cases, enough heat is produced to ignite the hydrogen. Sodium oxidizes rapidly in the presence of water (including water vapor in the air) and must be stored in airtight containers or kept immersed in naphtha or similar liquids. Because of its reactivity, sodium is dangerous to work with, and many precautions to ensure safe handling are required.
Because sodium is not found free in nature, it must be obtained by chemical means. It was first isolated in 1807 by Humphry Davy by the electrolysis of caustic soda. Commercially, sodium is obtained by the electrolysis of absolutely dry, fused sodium chloride in a special steel vessel called a Downs cell.
Sodium has many industrial uses. It is used in the preparation of tetraethyl and tetramethyl lead and in the manufacture of various chemical compounds, including some sodium compounds. It is also used as a reducing agent in the manufacture of detergents, as a heat transfer agent, and as a cooling agent in small nuclear reactors. In addition, some highways and streets are lighted with sodium-vapor lamps.
Compounds of SodiumThere are numerous sodium compounds, many of which are important commercially. Some, such as sodium chloride (common, or table, salt), borax, Chile saltpeter, and sodium carbonate, are readily obtained from natural mineral deposits. Others, such as sodium bicarbonate, sodium hydroxide, sodium sulfate, and hypo, are usually derived from other sodium compounds. Still other sodium compounds, such as sodium peroxide and sodium amide, are made by using the element sodium itself.
The sodium compound most important commercially as well as the most abundant in nature is sodium chloride, which is vital to much of the animal life on earth. Borax is sodium borate; it is used in certain kinds of soap and as a water softener. Chile saltpeter is a form of sodium nitrate; it is used as a fertilizer.
Sodium carbonate (soda ash), sodium bicarbonate (baking soda), and sodium hydroxide (caustic soda) are important industrial alkalies. Sodium sulfate is used in some detergents and in making some kinds of paper. Hypo, used as a fixer in photography, is sodium thiosulfate.
Sodium peroxide is an important bleaching and oxidizing agent. Sodium amide is used in organic synthesis and in the manufacture of sodium cyanide. Sodium cyanide is used in a number of industrial processes, including electroplating.
Symbol: Na. Atomic number: 11. Atomic weight: 22.98977. Specific gravity: 0.97. Melting point: 208 F. (97.8 C.). Boiling point: 1,621 F. (883 C.). Sodium has seven isotopes, of which only Na-23 is stable. Sodium is an alkali metal belonging to Group I-A of the Periodic Table and has a valence of +1.