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Columbia Encyclopedia entry: sodium

Sodium, a metallic chemical element; symbol Na [Lat. natrium]; at. no. 11; at. wt. 22.98977; m.p. 97.81°C; b.p. 892.9°C; sp. gr. 0.971 at 20°C; valence +1. Sodium is a soft, silver-white metal. Extremely reactive chemically, it is one of the alkali metals in Group 1 of the periodic table. Like potassium, which it closely resembles, it oxidizes rapidly in air; it also reacts violently with water, liberating hydrogen (which may ignite) and forming the hydroxide. It must be stored out of contact with air and water and should be handled carefully. Sodium combines directly with the halogens. The metal is usually prepared by electrolysis of the fused chloride (the Downs process); formerly, the chief method of preparation was by electrolysis of the fused hydroxide (the Castner process). Metallic sodium has limited use. It is used in sodium arc lamps for street lighting; pure or alloyed with potassium, it has found use as a heat-transfer liquid, e.g., in certain nuclear reactors. It is used principally in the manufacture of tetraethyl lead (a gasoline antiknock compound) and of sodamide, NaNH2, sodium cyanide, NaCN, sodium peroxide, Na2O2, and sodium hydride, NaH. Sodium compounds are extensively used in industry and for many nonindustrial purposes. Among the most important compounds are chloride (common salt, NaCl), bicarbonate (baking soda, NaHCO3), carbonate (soda ash, or washing soda, Na2CO3), hydroxide (caustic soda, or lye, NaOH), nitrate (Chile saltpeter, NaNO3), thiosulfate (hypo, Na2S2O3·5H2O), phosphates, and borax (Na2B4O7·10H2O). Sodium hydroxide is used wherever a cheap alkali is needed, for example, in making soap. Substances containing sodium impart a characteristic yellow color to a flame. Because of its activity sodium is not found uncombined in nature. It occurs abundantly and widely distributed in its compounds, which are present in rocks and soil, in the oceans, in salt lakes, in mineral waters, and in deposits in various parts of the world. Sodium compounds are found in the tissues of plants and animals. Sodium is an essential element in the diet, but some people must limit the amount of sodium in their food for medical reasons. Discovery of sodium is usually credited to Sir Humphry Davy, who prepared the metal from its hydroxide in 1807; its compounds have been known since antiquity.

Wikipedia search results for: Sodium

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Sodium is a metallic element with a symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals within "group 1". It has only one stable isotope, 23 Na. Elemental sodium was first isolated by Sir Humphry Davy in 1806 by passing an electric current through molten sodium hydroxide. Elemental sodium does not occur naturally on Earth, but quickly oxidizes in air and is violently reactive with water, so it must be stored in an inert medium, such as a liquid hydrocarbon. The free metal is used for some chemical synthesis, analysis, and heat transfer applications. Sodium ion is soluble in...more »

Columbia Encyclopedia search results: sodium

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sodium silicate
Sodium silicate, any one of several compounds containing sodium oxide, Na2O, and silica, Si2O, or a mixture of sodium silicates. Sodium orthosilicate is Na4SiO4 (or 2Na2O·SiO2); sodium metasil...
sodium thiosulfate
Sodium thiosulfate, Na2S2O3, colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3·5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposu...
sodium nitrate
Sodium nitrate, chemical compound, NaNO3, a colorless, odorless crystalline compound that closely resembles potassium nitrate (saltpeter or niter) in appearance and chemical properties. It is ...
sodium chloride
Sodium chloride, NaCl, common salt. Sodium chloride is readily soluble in water and insoluble or only slightly soluble in most other liquids. It forms small, transparent, colorless to white cu...
sodium sulfate
Sodium sulfate, chemical compound, Na2SO4. It is a white, orthorhombic crystalline compound at ordinary temperatures; above 100°C it assumes a monoclinic structure, and above about 250°C it as...
sodium benzoate
Sodium benzoate or benzoate of soda, chemical compound, C6H5CO2Na, colorless or white crystalline, aromatic compound; the sodium salt of benzoic acid. It is soluble in water and is used as a p...
sodium carbonate
Sodium carbonate, chemical compound, Na2CO3, soluble in water and very slightly soluble in alcohol. Pure sodium carbonate is a white, odorless powder that absorbs moisture from the air, has an...
sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate, chemical compound, NaHCO3, a white crystalline or granular powder, commonly known as bicarbonate of soda or baking soda. It is soluble in water...
sodium hydroxide
Sodium hydroxide, chemical compound, NaOH, a white crystalline substance that readily absorbs carbon dioxide and moisture from the air. It is very soluble in water, alcohol, and glycerin. It i...
Periodic Table of the Elements: Sodium
Periodic Table of the Elements: SodiumAtomic Number:11Atomic Symbol:NaSodiumAtomic Weight:22.98977ElectronConfiguration:2 · 8 · 1

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