|
|
Atomic Number: |
11 |
Melting Point: | 97.8 ºC | |
| Atomic Symbol: | Na | Boiling Point: | 883 ºC | ||
| Atomic Weight: | 22.98977 amu | Density: | 968
kg/m 3 |
||
| Atomic Radius: |
144.4 pm |
Oxidation States: | 1 | ||
| Covalent Radius: | 154 pm | Electron Configuration: | [Ne]3s1 | ||
| van der Waals Radius: |
227 pm |
State of Matter: | solid (nonmagnetic) |
(English, soda; Medieval Latin, sodanum: a headache remedy) Long recognized in compounds, sodium was first isolated by Davy in 1807 by electrolysis of caustic soda.
Sodium, like every reactive element, is never found free in nature. Sodium is a soft, bright, silvery metal which 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.
Sodium is present in fair abundance in the sun and stars. The D lines of sodium are among the most prominent in the solar spectrum. Sodium is the fourth most abundant element on earth, comprising about 2.6% of the earth's crust; it is the most abundant of the alkali group of metals.
It is now obtained commercially by the electrolysis of absolutely dry fused sodium chloride. This method is much cheaper than that of electrolyzing sodium hydroxide, as was used several years ago.
Metallic sodium is vital in the manufacture of esters and in the preparation of organic compounds. The metal may be used to improve the structure of certain alloys, descale metal, and purify molten metals. In combination with fatty acids, sodium is used in soap production. Sodium vapor is used in lamps as an efficient way of producing light from electricity.
Sodium compounds are important to the paper, glass, soap, textile, petroleum, chemical, and metal industries. Soap is generally a sodium salt of certain fatty acids. The most common compound of sodium is sodium chloride (NaCl) or table salt. The importance of common salt to animal nutrition has been recognized since prehistoric times. Besides common salt, among the many compounds that are of the greatest industrial importance are soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH), Chile saltpeter (NaNO3), di- and tri-sodium phosphates, sodium thiosulfate (hypo, Na2S2O3 . 5H2O), and borax (Na2B4O7 . 10H2O). It also occurs in many other minerals, such as soda niter, cryolite, amphibole, zeolite, etc. An alloy of sodium with potassium, NaK, is an important heat transfer agent.
Thirteen isotopes of sodium are recognized. The only stable isotope is Na-23. Sodium has two radioactive cosmogenic isotopes, Na-22 and Na-24.
Sodium metal should be handled with great care. It is highly reactive when in contact with water and it cannot be maintained in an inert atmosphere. It is flammable as 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 115oC.
Severe thermal and chemical burns will result at every point of human contact. Ingestion will cause burns and perforations of the gastrointestinal tract. Severe thermal burns, corrosion and ulceration of the skin and eyes may occur on direct contact.
