sodium (redirected from sodium-potassium-ATPase pump)

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.

---

sodium

Chemical element, one of the alkali metals, chemical symbol Na, atomic number 11. A very soft, silvery white metal, the sixth most abundant element on Earth, it occurs mainly as halite, never free. Extremely reactive, it is used as a chemical reagent and raw material, in metallurgy, as a heat exchanger (in nuclear power generators and certain types of engines), and in sodium-vapour lamps (see electric discharge lamp). Sodium is essential for life but rarely deficient in diets; high intake is linked to hypertension. Sodium in compounds, many of great industrial importance (including bicarbonate of soda, caustic soda, sodium nitrate [Chile saltpetre], and sodium chloride), has valence 1. Sodium carbonate, one of the four most important basic chemical commodities, is used in making glass, detergents, and cleansers. Sodium hypochlorite, familiar as household bleach, is also used to bleach paper pulp and textiles, to chlorinate water, and in some medicines. The sulfate is used in the kraft process and also used to make paperboard, glass, and detergents. The thiosulfate (hyposulfite, or “hypo”) is used to developed photographs.

---

sodium

a. a very reactive soft silvery-white element of the alkali metal group occurring principally in common salt, Chile saltpetre, and cryolite. Sodium and potassium ions maintain the essential electrolytic balance in living cells. It is used in the production of chemicals, in metallurgy, and, alloyed with potassium, as a cooling medium in nuclear reactors. Symbol: Na; atomic no.: 11; atomic wt.: 22.989768; valency: 1; relative density: 0.971; melting pt.: 97.81±0.03°C; boiling pt.: 892.9°C

b. (as modifier): sodium light