Atomic Number: 11
Atomic Symbol: Na
Atomic Weight: 22.98976
Melting Point: 1,621.4 F (883 C)
Boiling Point: 208.04 F (97.8 C)
Word origin: From the Medieval Latin, sodanum, a headache remedy, and the English word soda. Sodium's chemical symbol comes from the Latin word for sodium carbonate, natrium.
Discovery: Sodium was first isolated by Sir Humphry Davy in 1807 using electrolysis of caustic soda, although it had been long recognized in compounds.
Properties of sodium
Sodium is a soft, bright, silvery metal that floats on water. Decomposition in water results in the evolution of hydrogen and the formation of the hydroxide. It may or may not ignite spontaneously on water, depending on the amount of oxide and metal exposed to the water. It normally does not ignite in air at temperatures below 115 C (239 F), but careful handling is required. It cannot be maintained in an inert atmosphere and should not come into contact with water and other substances with which it reacts.
Like every reactive element, sodium is never found free in nature. The most common compound is sodium chloride (table salt), but sodium can be found in many other minerals, including amphibole, soda niter, cryolite and zeolite.
There are thirteen recognized isotopes of sodium.
Sources of sodium
Sodium is fairly abundant in the sun and stars. It is the fourth most abundant element on Earth, comprising about 2.6 percent of the planet's crust.
Uses of sodium
The importance of sodium chloride — common salt — in animal nutrition has been recognized since prehistoric times.
Sodium is now obtained commercially by the electrolysis of absolutely dry fused sodium chloride, a much less expensive process than that of electrolyzing sodium hydroxide.
There are a number of industrial compounds that contain sodium, including common salt, soda ash, baking soda, caustic soda, Chile saltpeter, di- and tri-sodium phosphates, sodium thiosulfate and borax. These compounds are used in the production of paper, glass, soap, textiles, petroleum, chemicals and metal.
Sodium lauryl sulfate and sodium laureth sulfate are used in shampoos, toothpaste and mouthwash, as well as foaming cleansing agents. The substances are irritants and should not come in contact with skin for more than a few minutes, such as the time it takes to wash your hair or brush your teeth.
Metallic sodium is vital in the preparation of organic compounds and the manufacture of esters. The metal may be used to improve the structure of certain alloys, descale metal and purify molten metals. An alloy of sodium with potassium, NaK, is critical heat transfer agent.
Diclofenac sodium is a prescription drug used to treat arthritis.
Sodium hypochlorite is commonly found in bleach, water purifiers and cleaning products.
Sodium citrate is the sodium salt of citric acid. It is sometimes used as an emulsifier for oils when making cheese.
(Source: Los Alamos National Laboratory)