sodium

(sō'dē-əm)

[SOD(A) + -IUM.]

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A chemical element, Na, atomic number 11, and atomic weight 22.9898. Sodium is between lithium and potassium in the periodic table. The element is a soft, reactive, low-melting metal with a specific gravity of 0.97 at 20°C (68°F). Sodium is commercially the most important alkali metal. The physical properties of metallic sodium are summarized in the table below. See also Periodic table.

Sodium ranks sixth in abundance among all the elements in the Earth's crust, which contains 2.83% sodium in combined form. Only oxygen, silicon, aluminum, iron, and calcium are more abundant. Sodium is, after chlorine, the second most abundant element in solution in seawater. The important sodium salts found in nature include sodium chloride (rock salt), sodium carbonate (soda and trona), sodium borate (borax), sodium nitrate (Chile saltpeter), and sodium sulfate. Sodium salts are found in seawater, salt lakes, alkaline lakes, and mineral springs. See also Alkali metals.

Sodium reacts rapidly with water, and even with snow and ice, to give sodium hydroxide and hydrogen. The reaction liberates sufficient heat to melt the sodium and ignite the hydrogen. When exposed to air, freshly cut sodium metal loses its silvery appearance and becomes dull gray because of the formation of a coating of sodium oxide.

Sodium does not react with nitrogen. Sodium and hydrogen react above about 200°C (390°F) to form sodium hydride. Sodium reacts with ammonia, forming sodium amide. Sodium also reacts with ammonia in the presence of coke to form sodium cyanide.

Sodium does not react with paraffin hydrocarbons but does form addition compounds with naphthalene and other polycyclic aromatic compounds and with arylated alkenes. The reaction of sodium with alcohols is similar to, but less rapid than, the reaction of sodium with water. Sodium reacts with organic halides in two general ways. One of these involves condensation of two organic, halogen-bearing compounds by removal of the halogen, allowing the two organic radicals to join directly. The second type of reaction involves replacement of the halogen by sodium, giving an organosodium compound. See also Organometallic compound.

Sodium chloride, or common salt, NaCl, is not only the form in which sodium is found in nature but (in purified form) is the most important sodium compound in commerce as well. Sodium hydroxide, NaOH, is also commonly known as caustic soda. Sodium carbonate, Na₂CO₃, is best known under the name soda ash.

The largest single use for sodium metal, accounting for about 60% of total production, is in the synthesis of tetraethyllead, an antiknock agent for automotive gasolines. A second major use is in the reduction of animal and vegetable oils to long-chain fatty alcohols; these alcohols are raw materials for detergent manufacture. Sodium is used to reduce titanium and zirconium halides to their respective metals. Sodium chloride is used in curing fish, meat packing, curing hides, making freezing mixtures, and food preparation (including canning and preserving). Sodium hydroxide is used in the manufacture of chemicals, cellulose film, rayon soap pulp, and paper. Sodium carbonate is used in the glass industry and in the manufacture of soap, detergents, various cleansers, paper and textiles, nonferrous metals, and petroleum products. Sodium sulfate (salt cake) is used in the pulp industry and in the manufacture of flat glass.

The sodium ion (Na⁺) is the main positive ion present in extracellular fluids and is essential for maintenance of the osmotic pressure and of the water and electrolyte balances of body fluids. Hydrolysis of adenosine triphosphate (ATP) is mediated by the membrane-bound enzyme Na⁺,K⁺-ATPase (this enzyme is also called sodium pump). The potential difference associated with the transmembrane sodium and potassium ion gradients is important for nerve transmission and muscle contraction. Sodium ion gradients are also responsible for various sodium ion–dependent transport processes, including sodium-proton exchange in the heart, sugar transport in the intestine, and sodium-lithium exchange and amino acid transport in red blood cells. See also Adenosine triphosphate (ATP); Potassium.

A dietary essential mineral; requirements are almost invariably satisfied by the normal diet. The body contains about 100 g of sodium and the average diet contains 3-6 g, equivalent to 7.5-15 g of sodium chloride (salt); the requirement is less than 0.5 g sodium/day. The intake varies widely between individuals and excretion varies accordingly. Excessive intake of sodium is associated with hypertension. See also salt-free diets; salt lick; sodium-potassium ratio; water balance.

A metallic element which is an important constituent of the human body. Sodium plays a major role in water balance.

Sodium is one of the major components of table salt. An investigation, called the Intersalt Study, of 10 000 people from 32 countries, found that there was a very strong correlation between a high sodium consumption and high blood pressure, especially in sodium-sensitive people. The results can be interpreted in a number of ways, but most dietitians agree that high sodium intakes can be harmful. Sodium can also increase the risk of oedema (swelling, particularly in joints, caused by an accumulation of fluids). The current average sodium intake of adults in the UK is 3.2 g per day. The government recommends that this should be decreased to 1.6 g. One simple way of reducing sodium intake is not to add table salt to food.

Sodium deficiency is rare, but it can occur if losses from heavy sweating are not replaced. A deficiency leads to nausea and muscular cramps. See also table salt.

A metallic element that plays a major role in the regulation of the volume of water in the body. Deficiency is rare, but it can occur if losses from heavy sweating are not replaced. Deficiency leads to nausea, dizziness, and muscle cramps. An excessive intake of sodium (e.g. by eating too much table salt) has been linked with high blood pressure and heart disease.

Sodium is normally present in food and in the body in its ionic (charged) form rather than as metallic sodium. Sodium is a positively charged ion or cation (Na⁺), and it forms salts with a variety of negatively charged ions (anions). Table salt or sodium chloride (NaCl) is an example of a sodium salt. In solution, NaCl dissociates into its ions, Na⁺ and Cl^-. Other sodium salts include those of both inorganic (e.g., nitrite or bicarbonate) and organic anions (e.g., citrate or glutamate) in aqueous solution, these salts also dissociate into Na⁺ and the respective anion.

Types and Amounts of Common Foods That Contain the Recommended Levels of Sodium

Only small amounts of salt or sodium occur naturally in foods, but sodium salts are added to foods during food processing or during preparation as well as at the table. Most sodium is added to foods as sodium chloride (ordinary table salt), but small amounts of other salts such as sodium bicarbonate (baking soda and baking powder), monosodium glutamate, sodium sulfide, sodium nitrate, and sodium citrate are also added. Studies in a British population found that 75 percent of sodium intake came from salts added during manufacturing and processing, 15 percent from table salt added during cooking and at the table, and only 10 percent from natural foods (Sanchez-Castillo et al., 1987). Most sources of drinking water are low in sodium. However, the use of home water softening systems may greatly increase the sodium content of water; the system should be installed so that water for cooking and drinking bypasses the water softening system.

The estimated minimum safe daily intake of sodium for an adult (0.5 grams) can be obtained from ¼ teaspoon of salt, ¼ of a large dill pickle, ⅕ can of condensed tomato soup, one frankfurter, or fifteen potato chips. The effect of salt added in processing is noted by the calculation that, whereas one would need to consume 333 cups of fresh green peas (with no salt added during cooking or at the table) in order to consume 0.5 grams of sodium, the estimated minimum safe daily intake of sodium is provided by only 1.4 cups of canned or 2.9 cups of frozen green peas.

Whereas the estimated minimum safe intake for an adult is 0.5 g/day of sodium (1.3 g/day of sodium chloride), average Americans consume between 2 and 5 g/day of sodium (between 5 and 13 g/day of sodium chloride) (National Research Council, 1989). Sodium chloride, or salt, intake varies widely among cultures and among individuals. In Japan, where consumption of salt-preserved fish and the use of salt for seasoning are customary, salt intake is high, ranging from 14 to 20 g/day (Kono et al., 1983). On the other hand, the unacculturated Yanomamo Indians, who inhabit the tropical rain forest of northern Brazil and southern Venezuela, do not use salt in their diet and have an estimated sodium chloride intake of less than 0.3 g/day (Oliver et al., 1975). In the United States, individuals who consume diets high in processed foods tend to have high sodium chloride intakes, whereas vegetarians consuming unprocessed food may ingest less than 1 g/day of salt. Individuals with salt intakes less than 0.5 g/day do not normally exhibit chronic deficiencies, but appear to be able to regulate sodium chloride retention adequately.

Recommended Intake of Sodium

The daily minimum requirement of sodium for an adult is the amount needed to replace the obligatory loss of sodium. The minimum obligatory loss of sodium by an adult in the absence of profuse sweating or gastrointestinal or renal disease has been estimated to be approximately 115 mg/day, which is due to loss of about 23 mg/day in the urine and feces and of 46 to 92 mg/day through the skin (National Research Council, 1989). Because of large variations in the degrees of physical activity and in environmental conditions, the estimated level of safe minimum intake for a 70-kg adult was set at 500 mg/day of sodium (equivalent to 1,300 mg/day of sodium chloride) by the National Research Council (1989). Although there is no established optimal range of intake of sodium chloride, it is recommended that daily salt intake should not exceed 6 grams because of the association of high intake with hypertension (National Research Council, 1989). The Dietary Guidelines for Americans, published in 2000, include a recommendation to choose and prepare foods with less salt.

Individuals who wish to lower their sodium or salt intakes should use less salt at the table and during cooking, avoid salty foods such as potato chips, soy sauce, pickled foods, and cured meat, and avoid processed foods such as canned pasta sauces, canned vegetables, canned soups, crackers, bologna, and sausages. Individuals should also become aware of and avoid "hidden" sources of sodium such as softened water, products made with baking soda, and foods containing additives in the form of sodium salts.

The need for sodium chloride is increased during pregnancy and lactation, with the estimated safe minimum intake being increased by 69 mg/day and 135 mg/day, respectively, for women during pregnancy and lactation. The estimated minimum requirement for sodium is 120 mg/day for infants between birth and 5 months of age and 200 mg/day for infants 6 to 11 months of age (National Research Council, 1989); these intakes are easily met by human milk or infant formulas. The estimated minimum requirements of sodium for children range from 225 mg/day at one year of age to 500 mg/day at 10 to 18 years of age.

General Overview of Role of Sodium in Normal Physiology

Total body sodium has been estimated at 100 grams (4.3 moles) for a 70-kg adult. In general, the cytoplasm of cells is relatively rich in potassium (K>) and poor in sodium (Na>) and chloride (Cl<) ions. The concentrations of sodium (and potassium and chloride) ions in cells and the circulating fluids are held remarkably constant, and small deviations from normal levels in humans are associated with malfunction or disease. Na⁺, K⁺, and Cl^- are referred to as electrolytes because of their role in the generation of gradients and electrical potential differences across cell membranes. Sodium and sodium gradients across cell membranes play several important roles in the body. First, sodium gradients are important in many transport processes. Sodium tends to enter cells down its electrochemical gradient (toward the intracellular compartment that has a lower Na⁺ concentration and a more negative charge compared to the extracellular fluid compartment). This provides a secondary driving force for absorption of Cl^- in the same direction as Na⁺ movement or for the secretion of K⁺ or hydrogen ions (H⁺) in the opposite direction in exchange for Na⁺. The sodium gradient is also used to drive the coupled transport of Na⁺ and glucose, galactose, and amino acids by certain carrier proteins in cell membranes; because as Na⁺ enters down its electrochemical gradient, uptake of glucose/galactose or amino acids can occur against their concentration gradient. Second, sodium ions, along with potassium ions, play important roles in generating resting membrane potentials and in generating action potentials in nerve and muscle cells. Nerve and muscle cell membranes contain gated channels through which Na⁺ or K⁺ can flow. In the resting state, these cell membranes are highly impermeable to Na⁺ and permeable to K⁺ (i.e., Na⁺ channels are closed and K⁺ channels are open). These gated channels open or close in response to chemical messengers or to the traveling current (applied voltage). Action potentials are generated in nerve and muscle due to opening of Na⁺ channels followed by their closing and the re-opening of K⁺ channels.

A third important function of sodium is its osmotic role as a major determinant of extracellular fluid volume. The volume of the extracellular fluid compartment is determined primarily by the total amount of osmotic particles present. Because Na⁺, along with Cl^-, is the major determinant of osmolarity of extracellular fluid, disturbances in Na⁺ balance will change the volume of the extracellular fluid compartment. Finally, because Na⁺ is a fixed cation, it also plays a role in acid-base balance in the body. An excess of fixed cations (versus fixed anions) requires an increase in the concentration of bicarbonate ions.

Consequences of Deficiency or Excessive Intake Levels

Sodium balance in the body is well controlled via regulation of Na⁺ excretion by the kidneys. The kidneys respond to a deficiency of Na⁺ in the diet by decreasing its excretion, and they respond to an excess of Na⁺ by increasing its excretion in the urine. Physiological regulatory mechanisms for conservation of Na⁺ seem to be better developed in humans than mechanisms for excretion of Na⁺, and pathological states characterized by inappropriate retention of Na⁺ are more common than those characterized by Na⁺ deficiency.

Retention of Na⁺ occurs when Na⁺ intake exceeds the renal excretory capacity. This can occur with rapid ingestion of large amounts of salt (for example, ingestion of seawater) or with too-rapid intravenous infusion of saline. Hypernatremia (abnormally high plasma concentration of Na⁺) and hypervolemia (abnormally increased volume of blood), resulting in acute hypertension, usually occur in these situations, and the Na⁺ regulatory mechanisms will cause natriuresis (urinary excretion of Na⁺) and water retention.

The body may be depleted of Na⁺ under extreme conditions of heavy and persistent sweating or when conditions such as trauma, chronic vomiting or diarrhea, or renal disease produce an inability to retain Na⁺. Sodium depletion produces hyponatremia (abnormally low plasma concentration of Na⁺) and hypovolemia (abnormally decreased volume of blood) which place the individual at risk of shock. Medical treatment includes replacement of Na⁺ and water to restore the circulatory volume. If the loss of Na⁺ is not due to renal disease, mechanisms to conserve Na⁺ and water are activated. Loss of Na⁺ can also be caused by the administration of diuretics, which inhibit Na⁺ and Cl^- reabsorption, or by untreated diabetes mellitus, which causes diuresis.

Regulatory Processes That Govern the Uptake and Excretion of Sodium

The kidneys are the main site of regulation of Na⁺ balance. The intestines play a relatively minor role. Under normal circumstances, about 99 percent of dietary Na⁺ and Cl^- are absorbed, and the remainder is excreted in the feces. Absorption of Na⁺ and Cl^- occurs along the entire length of the intestines; 90 to 95 percent is absorbed in the small intestine and the rest in the colon. Intestinal absorption of Na⁺ and Cl^- is subject to regulation by the nervous system, hormones, and paracrine agonists released from neurons in the enteric nervous system in the wall of the intestines. The most important of these factors is aldosterone, a steroid hormone produced and secreted by the zona glomerulosa cells of the adrenal cortex. Aldosterone stimulates absorption of Na⁺ and secretion of K⁺, mainly by the colon and, to a lesser extent, by the ileum.

The kidneys respond to a deficiency of Na⁺ in the diet by decreasing its excretion, and they respond to an excess by increasing its excretion in the urine. Urinary loss of Na⁺ is controlled by varying the rate of Na⁺ reabsorption from the filtrate by renal tubular cells. Individuals consuming diets that are low in Na⁺ efficiently reabsorb Na⁺ from the renal filtrate and have low rates of excretion of Na⁺. When there is an excess of Na⁺ from high dietary intake, little Na⁺ is reabsorbed by renal tubular cells, resulting in the excretion of the excess Na⁺ in the urine. As much as 13 g/day of Na⁺ can be excreted in the urine.

The most important regulator of renal excretion of Na⁺ and Cl^- is the renin-angiotensin-aldosterone system (Laragh, 1985). Sensors in the nephrons of the kidney respond to changes in Na⁺ load by influencing the synthesis and secretion of renin (Levens et al., 1981). A decrease in renal perfusion or Na⁺ load will increase the release of renin. In the circulation, renin acts to initiate the formation of active angiotensin II from angiotensinogen, a protein produced by the liver. Angiotensin II conserves body Na⁺ by stimulating Na⁺ reabsorption by the renal tubules and indirectly via stimulating secretion of aldosterone. Secretion of aldosterone by the adrenal cortex is stimulated by a low plasma Na⁺ concentration and by angiotensin II. Aldosterone stimulates cells of the renal tubules to reabsorb Na⁺.

Because of the close association of Na⁺ and Cl^- concentrations with effective circulating volume, Na⁺ (and Cl^-) retention results in proportionate water retention, and Na⁺ (and Cl^-) loss results in proportionate water loss. Expansion or contraction of the extracellular volume affects the activation of vascular pressure receptors, as well as the release of natriuretic peptides by certain tissues, and result in changes, mediated largely by antidiuretic hormone (ADH), in renal excretion of Na⁺, Cl^-, and water. A deficiency of sodium chloride and hypovolemia have also been shown to produce an increase in appetite for salt, which will increase sodium chloride intake.

Evidence That Sodium Intake May Be Related to Risk of Hypertension

Both epidemiological and experimental studies implicate habitual high dietary salt intake in the development of hypertension (Weinberger, 1996). Primary hypertension, or abnormally high blood pressure, is a significant risk factor for cardiovascular disease, stroke, and renal failure in industrialized societies. Diets that are high in fat, high in sodium, low in potassium, low in calcium, and low in magnesium may contribute to the development of hypertension (Reusser and McCarron, 1994).

Although epidemiological and experimental evidence suggest a positive correlation between habitual high-salt consumption and hypertension, controversy remains regarding the importance of sodium salts in the regulation of blood pressure and the mechanisms by which salt influences blood pressure. This is not surprising, because the response of blood pressure depends on an interplay of various factors, such as genetic susceptibility, body mass, cardiovascular factors, regulatory mechanisms mediated through the neural and hormonal systems, and renal function.

A large comprehensive study on the role of sodium in hypertension was carried out in fifty-two geographically separate centers in thirty-two countries by the INTERSALT Cooperative Research Group (Stamler, 1997). Four centers included in the study had median values for Na⁺ excretion that were under 1.3 g/day. Subjects in these four unacculturated centers had low blood pressure, rare or absent hypertension, and no age-related rise in blood pressure as occurred in populations in the other forty-eight centers in which mean values for Na⁺ excretion were between 2.4 and 5.6 grams Na⁺ per day. Although blood pressure and sodium intake appeared to be associated when all fifty-two centers were included, the correlation between systolic blood pressure and excretion of sodium was not significant when the four centers with the lowest median values of sodium excretion were excluded from the analysis.

Intervention studies of dietary salt restriction to lower blood pressure have produced mixed results. This may be explained by the facts that not all hypertensive patients are salt-sensitive and that many cases of hypertension are due to other causes. Nevertheless, various clinical trials indicate some beneficial effects of dietary restriction of sodium on blood pressure (Cutler et al., 1997; Reusser and McCarron, 1994) with response being greater in older patients, patients with the highest degree of restriction, and in nonoverweight, mildly hypertensive patients.

Researchers are currently attempting to identify the genetic basis of salt-sensitive hypertension and to identify polymorphisms associated with salt-sensitive hypertensive individuals. More than thirty different gene variations could be responsible for essential hypertension, and hypertension is considered to have a complex genetic basis. Further insight into the basis of hypertension may help to determine individuals for whom lowering salt intake would be beneficial and to facilitate the prescription of appropriate drugs.

Brief Outline of the History of Salt

Common salt is the chemical compound NaCl. Salt makes up nearly 80 percent of the dissolved material in seawater and is also widely distributed in solid deposits. It is found in many evaporative deposits, where it crystallizes out of evaporating brine lakes, and in ancient bedrock, where large extinct salt lakes and seas evaporated millions of years ago. Salt was in general use long before history began to be recorded. Salt has been used widely for the curing, seasoning, and preserving of foods.

Bibliography

Church, Charles F., and Helen N.Church. Food Values of Portions Commonly Used: Bowes and Church. Philadelphia: J. B. Lippincott, 1970.

Cutler, Jeffrey A., Dean Follmann, and P. Scott Allender. "Randomized Trials of Sodium Reduction: An Overview." American Journal of Clinical Nutrition 65 (1997, Supp.): 643S–651S.

Kono, Suminori, Masato Ikeda, and Michiharu Ogata. "Salt and Geographical Mortality of Gastric Cancer and Stroke in Japan." Journal of Epidemiology and Community Health 37 (1983): 43–46.

Laragh, John H. "Atrial Natriuretic Hormone, the Renin-Aldosterone Axis, and Blood Pressure—Electrolyte Homeostasis." New England Journal of Medicine 313 (1985): 1330–1340.

Levens, Nigel R., Michael J. Peach, and Robert M. Carey. "Role of Intrarenal Renin-Angiotensin System in the Control of Renal Function." Circulation Research 48 (1981):157–167.

National Research Council. Recommended Dietary Allowances. 10th ed. Washington, D.C.: National Academy Press, 1989, pp. 247–261.

Oliver, Walter J., Erik L. Cohen, and James V. Neel. "Blood Pressure, Sodium Intake and Sodium-Related Hormones in the Yanomamo Indians, a 'No-Salt' Culture." Circulation 52 (1975): 146–151.

Reusser, Molly E., and David A. McCarron. "Micronutrient Effects on Blood Pressure Regulation." Nutrition Reviews 52 (1994): 367–375.

Sanchez-Castillo, C. P., S. Warrender, T. P. Whitehead, and W. P. James. "An Assessment of the Sources of Dietary Salt in a British Population." Clinical Science 72 (1987): 95–102.

Sheng, Hwai-Ping. "Sodium, Chloride, and Potassium." In Biochemical and Physiological Aspects of Human Nutrition, edited by Martha H. Stipanuk, pp. 686–710. Philadelphia: W. B. Saunders Co., 2000.

Stamler, Jeremiah. "The INTERSALT Study: Background, Methods, Findings, and Implications." American Journal of Clinical Nutrition 65 (1997, Supp.): 626S–642S.

United States Department of Agriculture. Nutrition and Your Health: Dietary Guidelines for Americans. 5th ed.. Washington, D.C.: U. S. Government Printing Office, 2000.

Weinberger, Myron H. "Salt Sensitivity of Blood Pressure in Humans." Hypertension 27 (1996): 481–490.

—Martha H. Stipanuk

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A chemical element, atomic number 11, atomic weight 22.990, symbol Na. Sodium is the major cation of the extracellular fluid (ECF), constituting 90 to 95% of all cations in the blood plasma and interstitial fluid; it thus determines the osmolality of the ECF.

• s. acetate — a systemic and urinary alkalizer.
• s. acetylsalicylate — aspirin.
• s. acid phosphate, s. biphosphate — used as a dietary supplement of phosphorus for ruminants when only phosphorus is required and in small animals as a urinary acidifier.
• s. aminoarsonate — used as a feed additive to chickens and may cause arsenic poisoning if the dose rate is exceeded.
• s. antimony gluconate, s. stibogluconate — a pentavalent antimonial used in the treatment of leishmaniasis.
• s. arsanilate — used as a feed additive in the treatment of swine dysentery and in poultry and causes arsenic poisoning when dose rates are excessive.
• s. arsenite — used as a topical acaricide. See inorganic arsenic poisoning.
• s. arsenate — like the arsenite, a toxic compound used as an acaricide. Less toxic and less effective than the arsenite. See also inorganic arsenic poisoning.
• s. ascorbate — a form of ascorbic acid; vitamin C.
• s. azide — used in weed control and the prevention of rot in fruit; used in serum samples to prevent bacterial overgrowth.
• s. bentonite — see bentonite.
• s. benzoate — used topically as an antifungal agent in companion animals, with caffeine as a CNS stimulant and as a diagnostic aid in a liver function test.
• s. bicarbonate — a white powder found in most households in the form of baking soda; called also bicarbonate of soda. Used as a gastric antacid and as a systemic and urinary alkalinizer. See also milk shake. Used locally to remove mucus and to remove exudates and scabs.
• s. cacodylate — an organic compound yielding trivalent inorganic arsenic on metabolism in the body, similar in effects and toxicity to arsenic trioxide. Formerly used as a systemic treatment for chronic skin disease and capable of causing arsenic poisoning if used to excess.
• s.-calcium channels — see channel.
• s. carbonate — Na₂CO₃⋅H₂O, used as an alkalizing agent in pharmaceuticals, and has been used as a lotion or bath in the treatment of scaly skin, and as a detergent in companion animals.
• s. channels — see channel.
• s. chlorate — an oldfashioned herbicide which is quite palatable to farm animals and toxic in moderate amounts. Large doses cause abdominal pain, staggering and purging. Lower doses cause methemoglobinemia and dyspnea.
• s. chloride — salt; a necessary constituent of the body and therefore of the diet; sometimes used parenterally in solution to replenish electrolytes in the body.
• s. chloride nutritional deficiency — not a common occurrence but is seen in grazing animals on sodium deficient pastures, where heavy potash fertilizer has been applied in animals that are milking heavily, growing rapidly or losing a lot of sweat. Signs include pica, e.g. drinking urine, polydipsia, polyuria and decrease in appetite, milk yield, body weight, and urinary sodium and chloride.
• s. chloride poisoning (salt poisoning) — can occur via the diet due to accidental inclusion of too much salt; is usually too unpalatable. Most common is drinking of natural saline water from bore or deep well. Causes gastroenteritis, diarrhea and dehydration most noticeable in lactating animals. Animals are restless and play with water, looking for fresh water. Water contains also magnesium, sulfate and carbonate ions. If water intake restricted and salt intake normal a relative poisoning occurs. If combined with water deprivation causes polioencephalomalacia when the water intake returns to normal. In pigs the brain lesion is similar but because of the extensive infiltrations of eosinophils, characteristic of pigs, it is called eosinophilic meningoencephalitis.
• s. chloroacetate — a herbicide with very low toxicity potential.
• s. citrate — an alkalinizing agent; used also as an in vitro anticoagulant in blood stored for transfusion or diagnostic use.
• s. cyanide — a highly toxic industrial chemical and unlikely to enter the animal food chain unless as a result of a spill of reagents or industrial waste.
• s. diethyldithiocarbamate — a chelating agent used in the treatment for thallium poisoning; also used as an immunomodulator in the treatment of human immunodeficiency virus infection in humans.
• s. fluoride — a white, odorless powder used at one time for the treatment of ascariasis in pigs. Has no use in veterinary medicine comparable to its use as a prophylactic against dental caries in humans. See also fluorosis.
• s. fluoroacetamide — 1081; causes poisoning similar to sodium fluoroacetate (below).
• s. fluoroacetate — occurs naturally in some plants and used in agriculture as a rodenticide known as 1080. The latter is a restricted substance and is only sold on license. Two forms of poisoning occur: (1) myocardial failure resulting in sudden death in herbivora; signs are dyspnea, cardiac irregularity; (2) excitement and convulsions in pigs and dogs. Both poisonings are highly fatal. Plants containing fluoroacetate are Gastrolobium spp., Acacia georgina (gidgee), Dichapetalum spp., Palicourea spp.
• s. fluorosilicate — is used as an insecticide in bait form for crickets and grasshoppers and as an insecticide dust for poultry. It is as toxic as sodium fluoride.
• s. glutamate — the monosodium salt of l-glutamic acid; used in treatment of encephalopathies associated with liver diseases. Also used to enhance the flavor of foods.
• s. homeostasis — maintenance of the body's sodium status at an appropriate level; effected principally by aldosterone increasing tubular resorption of sodium from the glomerular filtrate.
• s. hyaluronate — used in the treatment of degenerative joint disease in horses. See also hyaluronic acid.
• s. hydroxide — an all-purpose caustic. Its biggest use in veterinary science is to clean down fat-laden surfaces in abattoirs prior to disinfection.
• s. hypochlorite — a compound having germicidal, deodorizing and bleaching properties; used in solution to disinfect utensils, and in diluted form (Dakin's solution) as a local antibacterial and to irrigate wounds. A common disinfectant for a wide variety of uses in veterinary medicine, including application to cow's teats in mastitis control programs. Called also bleach.
• s. iodide — a compound used as a source of iodine and as an expectorant. At times used parenterally in the treatment of extensive ringworm, actinobacillosis and actinomycosis. Overuse causes iodism.
• s. lactate — a compound used in solution to replenish body fluids and electrolytes.
• s. lauryl sulfate — an anionic surface-active agent used in shampoos as a detergent and wetting agent to increase skin penetration of active ingredients.
• s. metabisulfite — used as an antioxidant and as an aid in the making of ensilage. Also used as a preservative on meat, as a source of sulfur dioxide.
• s. methanearsonate — a herbicide—monosodium acid methanearsonate—causes arsenic poisoning.
• s. molybdate — used in salt mixture and as pasture topdressing as a prophylaxis against chronic copper poisoning in ruminants.
• s. monofluoroacetate — see sodium fluoroacetate (above).
• s. nitrate — used in food preservation especially meat pickling and as a fertilizer. Can cause nitrate–nitrite poisoning or nitrite poisoning in ruminants.
• s. nitrite — a vasodilator; used in the treatment of cyanide poisoning. Can cause methemoglobinemia and death from anoxia.
• s. oleate — used by local injection in horses to cause inflammation and aid healing of chronic injuries such as splints and bucked shins.
• s. oxalate — see soluble oxalate poisoning.
• s. pentachlorophenate — used as a fungicide in wood preservatives. Acute poisoning after heavy dosing causes dyspnea and death due to respiratory failure.
• s. perborate — an oxidizing agent; used as a topical antiseptic and mouthwash.
• s. phosphate — an osmotic cathartic.
• s.-potassium-ATPase pump — see pump.
• s.-potassium channels — see channel.
• s./potassium ratio — a low ratio, indicating hyponatremia and hyperkalemia, is characteristic of hypoadrenocorticism.
• s. propionate — used in the prophylaxis and treatment of acetonemia in cows, and as a fungistat both topically and in preparations for animal medication.
• s. pump — see sodium pump.
• s.-restricted diets — used in the dietary management of heart disease and hypertension in dogs and cats.
• s. salicylate — an analgesic, antipyretic compound. See salicylate.
• s. selenite — used as treatment for severe nutritional deficiency of selenium. Overdose will cause poisoning by selenium.
• s. sulfanilate — rate of excretion is used as a sensitive test of urinary function. See also sulfanilate.
• s. sulfate — an osmotic cathartic; also used as a diuretic and sometimes applied topically in solution to relieve edema and pain of infected wounds. Called also Glauber's salts.
• s. sulfite test — 1. precipitates protein out of solution; a dramatic test for protein in urine.
— 2. a turbidity test on serum for proximate estimation of gamma globulin content and immunological status of newborn calf.
• s. tetraborate — called also borax; used as a weak disinfectant.
• s. thiosulfate — a compound used in the treatment of cyanide poisoning, and used in measuring the volume of extracellular body fluid and the renal glomerular filtration rate.
• s. trichloroacetate — a nontoxic herbicide.
• s. versenate — see edetate.

A soft, grayish metal of the alkaline metals group. Its atomic number is 11, and its atomic weight is 22.9898. Sodium is one of the most important elements in the body. Sodium ions are involved in acid-base balance, water balance, the transmission of nerve impulses, and the contraction of muscle. The recommended daily intake of sodium is 250 to 750 mg for infants, 900 to 2,700 mg for children, and 1,100 to 3,300 mg for adults.

• Pure metals
• Elements - sodium: Na; atomic number 11, atomicweight 23

This article is about the chemical element. For the PlayStation Home game, see Sodium (PlayStation Home).

neon ← sodium → magnesium Li ↑ Na ↓ K 11Na Periodic table
Appearance
silvery white metallic Spectral lines of sodium
General properties
Name, symbol, number	sodium, Na, 11
Pronunciation	/ˈsoʊdiəm/ SOH-dee-əm
Element category	alkali metal
Group, period, block	1, 3, s
Standard atomic weight	22.98976928(2)
Electron configuration	[Ne] 3s1
Electrons per shell	2,8,1 (Image)
Physical properties
Phase	solid
Density (near r.t.)	0.968 g·cm−3
Liquid density at m.p.	0.927 g·cm−3
Melting point	370.87 K, 97.72 °C, 207.9 °F
Boiling point	1156 K, 883 °C, 1621 °F
Critical point	(extrapolated) 2573 K, 35 MPa
Heat of fusion	2.60 kJ·mol−1
Heat of vaporization	97.42 kJ·mol−1
Molar heat capacity	28.230 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 554 617 697 802 946 1153
Atomic properties
Oxidation states	+1, -1 (strongly basic oxide)
Electronegativity	0.93 (Pauling scale)
Ionization energies (more)	1st: 495.8 kJ·mol−1
	2nd: 4562 kJ·mol−1
	3rd: 6910.3 kJ·mol−1
Atomic radius	186 pm
Covalent radius	166±9 pm
Van der Waals radius	227 pm
Miscellanea
Crystal structure	body-centered cubic
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 47.7 nΩ·m
Thermal conductivity	142 W·m−1·K−1
Thermal expansion	(25 °C) 71 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 3200 m·s−1
Young's modulus	10 GPa
Shear modulus	3.3 GPa
Bulk modulus	6.3 GPa
Mohs hardness	0.5
Brinell hardness	0.69 MPa
CAS registry number	7440-23-5
Most stable isotopes
Main article: Isotopes of sodium
iso NA half-life DM DE (MeV) DP 22Na trace 2.602 y β+→γ 0.5454 22Ne* 1.27453(2)[1] 22Ne ε→γ - 22Ne* 1.27453(2) 22Ne β+ 1.8200 22Ne 23Na 100% 23Na is stable with 12 neutrons
v t e · r

Sodium ( /ˈsoʊdiəm/ SOH-dee-əm) is a chemical element with the symbol Na (from Latin: natrium) and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is ²³Na. It is an abundant element that exists in numerous minerals such as feldspars, sodalite and rock salt. Many salts of sodium are highly soluble in water and are thus present in significant quantities in the Earth's bodies of water, most abundantly in the oceans as sodium chloride.

Many sodium compounds are useful, such as sodium hydroxide (lye) for soapmaking, and sodium chloride for use as a deicing agent and a nutrient. Sodium is an essential element for all animals and some plants. In animals, sodium ions are used against potassium ions to build up charges on cell membranes, allowing transmission of nerve impulses when the charge is dissipated; it is therefore classified as a dietary inorganic macro-mineral.

The free metal, elemental sodium, does not occur in nature but must be prepared from sodium compounds. Elemental sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. The same ion is also a component of many minerals, such as sodium nitrate.

Contents 1 Characteristics 1.1 Physical 1.2 Chemical 1.3 Isotopes 1.4 Occurrence 2 Compounds 2.1 Aqueous solutions 2.1.1 Analysis 2.2 Electrides and sodides 2.3 Organosodium compounds 3 History 4 Commercial production 5 Applications 5.1 Free element 5.1.1 Heat transfer 5.2 Compounds 6 Biological role 7 Precautions 8 See also 9 References 10 External links

Characteristics

Physical

Emission spectrum for sodium, showing the D line.

A positive flame test for sodium has a bright yellow color.

Sodium at standard temperature and pressure is a soft metal that can be readily cut with a knife and is a good conductor of electricity. Freshly exposed, sodium has a bright, silvery luster that rapidly tarnishes and forms a white oxide layer. These properties change at elevated pressures: at 1.5 Mbar, the color changes to black, then to red transparent at 1.9 Mbar, and finally clear transparent at 3 Mbar. All of these allotropes are insulators and electrides.^[2]

When sodium or its compounds are introduced into a flame, they turn it yellow,^[3] because the excited 3s electrons of sodium emit a photon when they fall from 3p to 3s; the wavelength of this photon corresponds to the D line at 589.3 nm. Spin-orbit interactions involving the electron in the 3p orbital split the D line into two; hyperfine structures involving both orbitals cause many more lines.^[4] Lasers emitting light at the D line are used to create artificial laser guide stars that assist in the adaptive optics for large, land-based visible light telescopes.

Chemical

Sodium metal is highly reducing, with the reduction of sodium ions requiring −2.71 volts;^[5] other alkali metals like potassium and lithium have more negative potentials.^[6] Hence, the extraction of sodium metal from its compounds (such as with sodium chloride) uses a significant amount of energy.^[7] In terms of handling properties, sodium is generally less reactive than potassium and more reactive than lithium.^[8] Like all the alkali metals, it reacts exothermically with water, to the point that sufficiently large pieces melt to a sphere and then explode; this reaction produces caustic sodium hydroxide and flammable hydrogen gas. When burned in dry air, it mainly forms sodium peroxide as well as some sodium oxide. In moist air, sodium hydroxide results.^[7]

Isotopes

Main article: Isotopes of sodium

20 isotopes of sodium are known, but only ²³Na is stable. Two radioactive, cosmogenic isotopes are the byproduct of cosmic ray spallation: ²²Na with a half-life of 2.6 years and ²⁴Na with a half-life of 15 hours; all other isotopes have a half-life of less than one minute.^[9] Two nuclear isomers have been discovered, the longer-lived one being ^24mNa with a half-life of around 20.2 microseconds. Acute neutron radiation, such as from a nuclear criticality accident, converts some of the stable ²³Na in human blood to ²⁴Na; by measuring the concentration of ²⁴Na in relation to ²³Na, the neutron radiation dosage of the victim can be calculated.^[10]

Occurrence

²³Na is created in the carbon-burning process by fusing two carbon atoms together; this requires temperatures above 600 megakelvins and a star with at least three solar masses.^[11] The Earth's crust has 2.6% sodium by weight, making it the sixth most abundant element there.^[12] Because of its high reactivity, it is never found as a pure element. It is found in many different minerals, some very soluble, such as halite and natron, others much less soluble such as amphibole, and zeolite. The insolubility of certain sodium minerals such as cryolite and feldspar arises from their polymeric anions, which in the case of feldspar is a polysilicate. In the interstellar medium, sodium is identified by the D line; though it has a high vaporization temperature, its abundance allowed it to be detected by Mariner 10 in Mercury's atmosphere.^[13]

Compounds

See also Category: Sodium compounds

Structure of sodium chloride, showing octahedral coordination around Na⁺ and Cl^- centres. This framework disintegrates upon dissolution in water and reassembles upon evaporation.

Sodium compounds are of immense commercial importance, being particularly central to industries producing glass, paper, soap, and textiles.^[14] The sodium compounds that are the most important are common salt (NaCl), soda ash (Na₂CO₃), baking soda (NaHCO₃), caustic soda (NaOH), sodium nitrate (NaNO₃), di- and tri-sodium phosphates, sodium thiosulfate (Na₂S₂O₃·5H₂O), and borax (Na₂B₄O₇·10H₂O).^[15] In its compounds, sodium is usually ionically bonded to water and anions, and is viewed as a hard Lewis acid.^[16]

Aqueous solutions

Sodium tends to form water-soluble compounds, such as halides, sulfates, nitrates, carboxylates and carbonates. The main species in water are the aquo complexes [Na(H₂O)_n]⁺ where n = 4–6.^[17]

The high affinity of sodium for oxygen-based ligands is the basis of crown ethers. Functionally related but more complex ligands are several macrolide antibiotics, which function by interfering with the transport of Na⁺ in the infecting organism.

The precipitation of sodium salts from water solution is uncommon because sodium salts typically have a high affinity for water. An illustrative sodium salt exhibiting low solubility in water is sodium bismuthate (NaBiO₃).^[18] Since sodium salts are so soluble in water, they are usually isolated as solids by evaporation of these aqueous solutions or by precipitation with an organic solvent. For example, 360 g of sodium chloride will dissolve in one litre of water at room temperature. The addition of ethanol to such solutions can cause solid NaCl to separate (precipitate), because only 0.35 g/litre of sodium chloride will dissolve in the alcohol.^[19]

Related to sodium compounds' good water solubility, these compounds do not dissolve well in organic solvents. Crown ethers, especially 15-crown-5 may be used as a phase-transfer catalyst.

Analysis

Bulk sodium content may be determined by treating a sample with a large excess of uranyl zinc acetate; uranyl zinc sodium acetate precipitates as the hexahydrate ((UO₂)₂ZnNa(CH₃CO₂)·6H₂O), and its mass can be weighed (see gravimetry). The presence of caesium and rubidium does not interfere with this reaction, but the potassium and lithium must be removed prior to analysis.^[20][21]

Lower concentrations of sodium may be determined by atomic absorption spectrophotometry,^[22] and by potentiometry using ion-selective electrodes.^[23][24]

Electrides and sodides

Like the other alkali metals, sodium dissolves in ammonia and some amines to give deeply coloured solutions; evaporation of these solutions leaves a shiny film of metallic sodium. The solutions contain the coordination complex (Na(NH₃)₆)⁺, whose positive charge is counterbalanced by electrons as anions; cryptands permit the isolation of these complexes as crystalline solids. Cryptands, like crown ethers and other ionophores, have a high affinity for the sodium ion; derivatives of the alkalide Na^- are obtainable^[25] by the addition of cryptands to solutions of sodium in ammonia via disproportionation.^[26]

Organosodium compounds

The structure of the complex of sodium (Na⁺, shown in yellow) and the antibiotic monensin-A.

Many organosodium compounds have been prepared. Because of the high polarity of the C-Na bonds, they behave like sources of carbanions (salts with organic anions). Some well known derivatives include sodium cyclopentadienide (NaC₅H₅) and trityl sodium ((C₆H₅)₃CNa).^[27]

History

Salt has been an important commodity in human activities, as shown by the English word salary, which derives from salarium, the wafers of salt sometimes given to Roman soldiers along with their other wages. In medieval Europe, a compound of sodium with the Latin name of sodanum was used as a headache remedy. The name sodium is thought to originate from the Arabic suda, meaning headache, as the headache-alleviating properties of sodium carbonate or soda were well known in early times.^[28] The chemical abbreviation for sodium was first published by Jöns Jakob Berzelius in his system of atomic symbols,^[29] and is a contraction of the element's new Latin name natrium, which refers to the Egyptian natron,^[28] a natural mineral salt primarily made of hydrated sodium carbonate. Natron historically had several important industrial and household uses, later eclipsed by other sodium compounds. Although sodium, sometimes called soda, had long been recognised in compounds, the metal itself was not isolated until 1807 by Humphry Davy through the electrolysis of sodium hydroxide.^[30][31]

Sodium imparts an intense yellow color to flames. As early as 1860, Kirchhoff and Bunsen noted the high sensitivity of a sodium flame test, and stated in Annalen der Physik und Chemie:^[32]

“

In a corner of our 60 m3 room farthest away from the apparatus, we exploded 3 mg. of sodium chlorate with milk sugar while observing the nonluminous flame before the slit. After a while, it glowed a bright yellow and showed a strong sodium line that disappeared only after 10 minutes. From the weight of the sodium salt and the volume of air in the room, we easily calculate that one part by weight of air could not contain more than 1/20 millionth weight of sodium.

”

Commercial production

Enjoying rather specialized applications, only about 100,000 tonnes of metallic sodium are produced annually.^[14] Metallic sodium was first produced commercially in 1855 by carbothermal reduction of sodium carbonate at 1100 °C, in what is known as the Deville process:^[33][34][35]

Na₂CO₃ + 2 C → 2 Na + 3 CO

A related process based on the reduction of sodium hydroxide was developed in 1886.^[33]

Sodium is now produced commercially through the electrolysis of molten sodium chloride, based on a process patented in 1924.^[36][37] This is done in a Downs Cell in which the NaCl is mixed with calcium chloride to lower the melting point below 700 °C. As calcium is less electropositive than sodium, no calcium will be formed at the anode. This method is less expensive than the previous Castner process of electrolyzing sodium hydroxide.

Reagent-grade sodium in tonne quantities sold for about US$3.30/kg in 2009; lower purity metal sells for considerably less. The market for sodium is volatile due to the difficulty in its storage and shipping; it must be stored under a dry inert gas atmosphere or anhydrous mineral oil to prevent the formation of a surface layer of sodium oxide or sodium superoxide. These oxides can react violently in the presence of organic materials. Sodium will also burn violently when heated in air.^[38] Smaller quantities of sodium cost far more, in the range of US$165/kg; the high cost is partially due to the expense of shipping hazardous material.^[39]

Applications

Though metallic sodium has some important uses, the major applications of sodium use it in its many compounds; millions of tons of the chloride, hydroxide, and carbonate are produced annually.

Free element

Metallic sodium is mainly used for the production of sodium borohydride, sodium azide, indigo, and triphenylphosphine. Previous uses were for the making of tetraethyllead and titanium metal; because applications for these chemicals were discontinued, the production of sodium declined after 1970.^[14] Sodium is also used as an alloying metal, an anti-scaling agent,^[40] and as a reducing agent for metals when other materials are ineffective. Sodium vapor lamps are often used for street lighting in cities and give colours ranging from yellow-orange to peach as the pressure increases.^[41] By itself or with potassium, sodium is a desiccant; it gives an intense blue colouration with benzophenone when the desiccate is dry.^[42] In organic synthesis, sodium is used in various reactions such as the Birch reduction, and the sodium fusion test is conducted to qualitatively analyse compounds.^[43] Many important medicines have sodium added to improve their bioavailability.^[14]

Heat transfer

NaK phase diagram, showing the melting point of sodium as a function of percentage of potassium in it. NaK with 77% potassium is eutectic and has the lowest melting point of the NaK alloys at −12.6 °C.^[44]

Liquid sodium is used as a heat transfer fluid in some fast reactors,^[45] due to its high thermal conductivity and low neutron absorption cross section, which is required to achieve a high neutron flux; the high boiling point allows the reactor to operate at ambient pressure. Drawbacks of using sodium include its opacity, which hinders visual maintenance, and its explosive properties. Radioactive sodium-24 may be formed by neutron activation during operation, posing a slight radiation hazard; the radioactivity stops within a few days after removal from the reactor. If a reactor needs to be frequently shut down, NaK is used; due to it being liquid at room temperature, cooling pipes do not freeze. In this case, the pyrophoricity of potassium means extra precautions against leaks need to be taken.

A different heat transfer application is in internal combustion engines with poppet valves. In high performance engines sometimes sodium-cooled valve stems are used to cool the valves. These hollow valve stems are partially filled with sodium and act as a heat pipe.

Compounds

This section requires expansion.

Two equivalent images of the chemical structure of sodium stearate, a typical soap.

Most soaps are sodium salts of fatty acids. Sodium soaps are harder (higher melting) soaps than potassium soaps.^[15] Sodium chloride is extensively used for anti-icing and de-icing as well as and as a preservative; sodium bicarbonate is mainly used for cooking.

Biological role

Main article: Sodium in biology

Sodium is an essential nutrient that regulates blood volume, blood pressure, osmotic equilibrium and pH; the minimum physiological requirement for sodium is 500 milligrams per day.^[46] Sodium chloride is the principal source of sodium in the diet, and is used as seasoning and preservative, such as for pickling and jerky; most of it comes from processed foods.^[47] The DRI for sodium is 2.3 grams per day,^[48] but on average people in the United States consume 3.4 grams per day,^[49] the minimum amount that promotes hypertension;^[50] this in turn causes 7.6 million premature deaths worldwide.^[51]

The renin-angiotensin system and the atrial natriuretic peptide regulate the amount of fluid in the body. Reduction of blood pressure and sodium concentration in the kidney result in the production of renin, which in turn produces aldosterone, retaining sodium in the urine. Because of this, the osmotic pressure changes and osmoregulation systems generate the antidiuretic hormone, causing the body to retain water and restore its total amount of fluid. Receptors in the heart and blood vessels sense the resulting distension and pressure, leading to production of the atrial natriuretic peptide, causing the body to lose sodium in the urine; the osmoregulation systems detect this and remove water, restoring the total fluid levels.

Sodium is also important in neuron function and osmoregulation between cells and the extracellular fluid; their distribution is mediated in all animals by Na⁺/K⁺-ATPase.^[52] Hence, sodium is the most prominent cation in extracellular fluid: the 15 liters of it in a 70 kg human have around 50 grams of sodium, 90% of the body's total sodium content.

In C4 plants, sodium is a micronutrient that aids in metabolism, specifically in regeneration of phosphoenolpyruvate and synthesis of chlorophyll.^[53] In others, it substitutes for potassium in several roles, such as maintaining turgor pressure and aiding in the opening and closing of stomata.^[54] Excess sodium in the soil limits the uptake of water due to decreased water potential, which may result in wilting; similar concentrations in the cytoplasm can lead to enzyme inhibition, which in turn causes necrosis and chlorosis.^[55] To avoid these problems, plants developed mechanisms that limit sodium uptake by roots, store them in cell vacuoles, and control them over long distances;^[56] excess sodium may also be stored in old plant tissue, limiting the damage to new growth.

Precautions

Care is required in handling elemental sodium, as it is potentially explosive and generates flammable hydrogen and caustic sodium hydroxide upon contact with water; powdered sodium may combust spontaneously in air or oxygen.^[57] Excess sodium can be safely removed by hydrolysis in a ventilated cabinet; this is typically done by sequential treatment with isopropanol, ethanol and water. Isopropanol reacts very slowly, generating the corresponding alkoxide and hydrogen.^[58] Fire extinguishers based on water accelerate sodium fires; those based on carbon dioxide and bromochlorodifluoromethane lose their effectiveness when they dissipate. An effective extinguishing agent is Met-L-X, which comprises approximately 5% Saran in sodium chloride together with flow agents; it is most commonly hand-applied with a scoop. Other materials include Lith+, which has graphite powder and an organophosphate flame retardant, and dry sand.

See also

Books View or order collections of articles	Sodium Period 3 elements Alkali metals Chemical elements (sorted alphabetically) Chemical elements (sorted by number)
Portals Access related topics	Chemistry portal
Find out more on Wikipedia's Sister projects	Images and media from Commons Definitions from Wiktionary Textbooks from Wikibooks Learning resources from Wikiversity

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50. ^ Geleijnse, J. M.; Kok, F. J.; Grobbee, D. E. (2004). "Impact of dietary and lifestyle factors on the prevalence of hypertension in Western populations". European Journal of Public Health 14 (3): 235–239. doi:10.1093/eurpub/14.3.235. PMID 15369026. 
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External links

• The Periodic Table of Videos video of Sodium at YouTube
• Etymology of "natrium" – source of symbol Na
• The Wooden Periodic Table Table's Entry on Sodium
• Dietary Sodium
• Sodium isotopes data from The Berkeley Laboratory Isotopes Project's

v t e  Periodic table
H																															He
Li	Be																									B	C	N	O	F	Ne
Na	Mg																									Al	Si	P	S	Cl	Ar
K	Ca															Sc	Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn	Ga	Ge	As	Se	Br	Kr
Rb	Sr															Y	Zr	Nb	Mo	Tc	Ru	Rh	Pd	Ag	Cd	In	Sn	Sb	Te	I	Xe
Cs	Ba	La	Ce	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho	Er	Tm	Yb	Lu	Hf	Ta	W	Re	Os	Ir	Pt	Au	Hg	Tl	Pb	Bi	Po	At	Rn
Fr	Ra	Ac	Th	Pa	U	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr	Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Cn	Uut	Uuq	Uup	Uuh	Uus	Uuo
Alkali metals Alkaline earth metals Lanthanides Actinides Transition metals Post-transition metals Metalloids Other nonmetals Halogens Noble gases Unknown chem. properties
Large version

v t e Sodium compounds NaAlO2 NaBH4 NaBH3(CN) NaBiO3 NaBr NaBrO3 NaCH3COO NaC6H5CO2 NaC6H4(OH)CO2 NaCN NaCl NaClO NaClO2 NaClO3 NaClO4 NaF NaH NaHCO3 NaH2PO4 NaHSO3 NaHSO4 NaI NaIO3 NaIO4 NaMnO4 NaN3 NaNH2 NaNO2 NaNO3 NaO2 NaOH NaPO2H2 NaReO4 NaSCN NaSH NaTcO4 NaVO3 Na2CO3 Na2C2O4 Na2CrO4 Na2Cr2O7 Na2MnO4 Na2MoO4 Na2O Na2O2 Na2O(UO3)2 Na2S Na2SO3 Na2SO4 Na2S2O3 Na2S2O4 Na2S2O5 Na2S2O6 Na2S2O7 Na2S2O8 Na2Se Na2SeO3 Na2SeO4 Na2SiO3 Na2Te Na2TeO3 Na2Ti3O7 Na2U2O7 NaWO4 Na2Zn(OH)4 Na3N Na3P Na3VO4 Na4Fe(CN)6 Na5P3O10 Chemical formulas

v t e Alkali metals     Lithium Li Atomic Number: 3 Atomic Weight: 6.941 Melting Point: 453.85 K Boiling Point: 1615 K Specific mass: 0.534 g/cm3 Electronegativity: 0.98 Sodium Na Atomic Number: 11 Atomic Weight: 22.98976928 Melting Point: 371.15 K Boiling Point: 1156 K Specific mass: 0.97 g/cm3 Electronegativity: 0.96 Potassium K Atomic Number: 19 Atomic Weight: 39.0983 Melting Point: 336.5 K Boiling Point: 1032 K Specific mass: 0.86 g/cm3 Electronegativity: 0.82 Rubidium Rb Atomic Number: 37 Atomic Weight: 85.4678 Melting Point: 312.79 K Boiling Point: 961 K Specific mass: 1.53 g/cm3 Electronegativity: 0.82 Caesium Cs Atomic Number: 55 Atomic Weight: 132.9054519 Melting Point: 301.7 K Boiling Point: 944 K Specific mass: 1.93 g/cm3 Electronegativity: 0.79 Francium Fr Atomic Number: 87 Atomic Weight: [223] Melting Point: 300.15 K Boiling Point: 950 K Specific mass: 1.87 g/cm3 Electronegativity: 0.7

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Dansk (Danish)
n. - natrium

idioms:

• sodium bicarbonate    natriumbikarbonat, tvekulsurt natron
• sodium carbonate    natriumkarbonat, kulsurt natron
• sodium chloride    natriumklorid, kogsalt
• sodium hydroxide    natriumhydroxyd
• sodium lamp    natriumlampe
• sodium nitrate    natriumnitrat, salpetersurt natron
• sodium-vapour lamp    natriumdamplampe

Nederlands (Dutch)
natrium

Français (French)
n. - sodium, soude

idioms:

• sodium bicarbonate    bicarbonate de soude
• sodium carbonate    carbonate de sodium
• sodium chloride    chlorure de sodium
• sodium hydroxide    hydroxyde de sodium
• sodium lamp    lampe/ampoule au sodium
• sodium nitrate    nitrate de sodium
• sodium-vapour lamp    lampe à vapeur de sodium

Deutsch (German)
n. - Natrium

idioms:

• sodium bicarbonate    doppeltkohlensaures Natrium
• sodium carbonate    Natriumkarbonat
• sodium chloride    Natriumchlorid
• sodium hydroxide    Ätznatron
• sodium lamp    Natriumdampflampe
• sodium nitrate    Natriumnitrat
• sodium-vapour lamp    Natriumdampflampe

Ελληνική (Greek)
n. - (χημ.) νάτριο

idioms:

• sodium bicarbonate    (χημ.) διττανθρακικό νάτρι, σόδα ζαχαροπλαστικής
• sodium carbonate    (χημ.) ανθρακική σόδα
• sodium chloride    χλωριούχο νάτριο
• sodium hydroxide    (χημ.) καυστική σόδα
• sodium lamp    φανάρι του δρόμου
• sodium nitrate    νιτρικό νάτριο
• sodium-vapour lamp    φανάρι του δρόμου

Italiano (Italian)
sodio

idioms:

• sodium bicarbonate    bicarbonato di sodio
• sodium carbonate    carbonato di sodio
• sodium chloride    cloruro di sodio
• sodium hydroxide    soda caustica
• sodium lamp    lampada al sodio
• sodium nitrate    nitrato di sodio
• sodium-vapour lamp    lampada ai vapori di sodio

Português (Portuguese)
n. - sódio (m)

idioms:

• sodium bicarbonate    bicarbonato de sódio (m)
• sodium carbonate    carbonato de sódio (m)
• sodium chloride    cloreto de sódio (m)
• sodium hydroxide    hidróxido de sódio (m)
• sodium lamp    lâmpada de sódio (f)
• sodium nitrate    nitrato de sódio (m)
• sodium-vapour lamp    lâmpada de vapor de sódio (f)

Русский (Russian)
натрий

idioms:

• sodium bicarbonate    двууглекислый натрий
• sodium carbonate    углекислый натрий
• sodium chloride    хлористый натрий, поваренная соль
• sodium hydroxide    едкий натр
• sodium lamp    натриевая лампа
• sodium nitrate    нитрат натрия
• sodium-vapour lamp    натриевая лампа

Español (Spanish)
n. - sodio

idioms:

• sodium bicarbonate    bicarbonato sódico
• sodium carbonate    carbonato sódico
• sodium chloride    cloruro de sodio, cloruro sódico
• sodium hydroxide    hidróxido de sodio
• sodium lamp    lámpara de vapor de sodio
• sodium nitrate    nitrato de sodio
• sodium-vapour lamp    lámpara de vapor de sodio

Svenska (Swedish)
n. - natrium

中文（简体）(Chinese (Simplified))
钠

idioms:

• sodium bicarbonate    碳酸氢钠, 小苏打
• sodium carbonate    碳酸钠
• sodium chloride    食盐, 氯化钠
• sodium hydroxide    氢氧化钠, 烧碱
• sodium lamp    钠灯
• sodium nitrate    硝酸钠
• sodium-vapour lamp    钠蒸气灯

中文（繁體）(Chinese (Traditional))
n. - 鈉

idioms:

• sodium bicarbonate    碳酸氫鈉, 小蘇打
• sodium carbonate    碳酸鈉
• sodium chloride    食鹽, 氯化鈉
• sodium hydroxide    氫氧化鈉, 燒鹼
• sodium lamp    鈉燈
• sodium nitrate    硝酸鈉
• sodium-vapour lamp    鈉蒸氣燈

한국어 (Korean)
n. - 나트륨(금속 원소)

日本語 (Japanese)
n. - ナトリウム

idioms:

• sodium bicarbonate    重炭酸ナトリウム
• sodium carbonate    炭酸ソーダ, 炭酸ナトリウム, 結晶ソーダ
• sodium chloride    塩化ナトリウム
• sodium hydroxide    水酸化ナトリウム, 苛性ソーダ
• sodium lamp    ナトリウムランプ, ナトリウム灯
• sodium nitrate    硝酸ナトリウム

العربيه (Arabic)
‏(الاسم) فلز ألصوديم‏

עברית (Hebrew)
n. - ‮נתרן (יסוד מתכתי, AN, מס' אטומי 11)‬

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