- Key People:
- Sir Humphry Davy
- Joseph-Louis Gay-Lussac
- Rudolf Fittig
- Related Topics:
- chemical element
- human nutrition
- sodium deficiency
- sodium-24
- sodium-22
- On the Web:
- UH Pressbooks - Human Nutrition - Sodium (Nov. 09, 2026)
sodium
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What is sodium?
Sodium (Na) is a chemical element belonging to the alkali metal group (Group 1 [Ia]) of the periodic table. It is a soft, silvery-white metal and the most abundant alkali metal, making up 2.8 percent of Earth's crust.
Because of its high reactivity, sodium is never found in its free state in nature. In 1807, Sir Humphry Davy first isolated elemental sodium through the electrolysis of fused sodium hydroxide (NaOH). Sodium is a crucial element for life, maintaining electrolyte balance in cells, and its salts are found in biological materials. Sodium is used in the production of dyes, perfumes, and various organic reductions. It serves as a deoxidant in metallurgy and a coolant in liquid-metal fast breeder reactors.
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Where is sodium found in nature?
Because it is extremely reactive, sodium is not found in its free state in nature. It is a constituent of silicate materials like feldspars and micas. Sodium is present in the spectra of stars, including the Sun, in both atomic and ionic forms.
Vast deposits of rock salt exist worldwide, and sodium nitrate deposits are found in Chile and Peru. The sodium content of the sea is roughly 1.05%, which corresponds to a concentration of about 3% of sodium halides. Also, the silicate material in meteorites has roughly 4.6 atoms of sodium for every 100 atoms of silicon.
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What are some common uses of sodium?
Sodium is a commercially significant alkali metal with varied applications. It is employed in the production of dyes and perfumes, the purification and polymerization of hydrocarbons, and organic reductions. Molten sodium functions as a heat-transfer fluid, useful as a coolant in liquid-metal fast breeder reactors.
Sodium compounds are also widely used. Sodium chloride, or common salt (NaCl), is used in food and for de-icing. Other applications include the production of chlorine and sodium hydroxide via electrolytic decomposition, and in the production of sodium carbonate (Na2CO3) via the Solvay process. Sodium hydroxide (NaOH), also known as lye or caustic soda, is the most widely used industrial alkali. Sodium-vapor lamps are used for street lighting.
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What does sodium look like and how does it behave?
Sodium (Na) is a chemical element in the alkali metal group. It is a soft, silvery-white metal and the sixth most abundant element on Earth, making up 2.8% of the Earth’s crust.
Sodium is highly reactive and does not occur in its free state in nature. It reacts with water to form sodium hydroxide (NaOH), a strong base. Sodium also reacts with air, and its reactivity is affected by humidity. In dry air, it forms sodium monoxide ((Na_2O)), while in ordinary air, it forms a sodium hydroxide film that absorbs carbon dioxide, creating sodium bicarbonate.
It is more reactive as a liquid than as a solid and can ignite at around 125 °C (257 °F). When burning, it emits a dense, white, caustic smoke that can cause choking and coughing, and it requires special dry-powder fire extinguishers because it reacts with carbon dioxide.
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Why is sodium important for the human body?
Sodium is vital for maintaining the balance of positive and negative ions in body fluids and tissues. It helps regulate tissue-water and acid-base balance, which are important for good nutritional status. Sodium is also essential for nerve impulse transmission and muscle contraction.
Sodium deficiency can result from excessive sweating, causing symptoms like weakness, apathy, nausea, and muscle cramps. However, sodium deficiency is rare because it is readily available in food, and the body has efficient conservation mechanisms.
Limiting sodium intake to no more than 2,400 mg daily is typically recommended to help reduce blood pressure.
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How can too much or too little sodium affect people and the environment?
Sodium imbalances can impact health and the environment.
How Sodium Imbalances Affect People
Too little sodium: Sodium deficiency, or hyponatremia, is rare but can occur due to heavy sweating, vomiting, diarrhea, or kidney disease. Symptoms include muscle cramps, nausea, dizziness, and weakness.
Too much sodium: High sodium intake is linked to hypertension, increasing the risk of heart disease and stroke. The WHO recommends limiting sodium in drinking water to 200 parts per million to avoid health issues like hypertension and heart disease.How Sodium Imbalances Affect the Environment
Excess salinity in water sources, caused by water pollution or land-use changes, harms freshwater biodiversity and makes the water unsuitable for drinking, food production, and industrial uses. High salinity in soils inhibits plant growth by causing dehydration and preventing nitrogen uptake, which leads to soil deterioration and farmland productivity loss. Sodic soils, with excess adsorbed sodium, become sticky when wet and hard when dry, which makes them nearly impervious to water and roots.
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News •
sodium (Na), chemical element of the alkali metal group (Group 1 [Ia]) of the periodic table. Sodium is a very soft silvery-white metal. Sodium is the most common alkali metal and the sixth most abundant element on Earth, comprising 2.8 percent of Earth’s crust. It occurs abundantly in nature in compounds, especially common salt—sodium chloride (NaCl)—which forms the mineral halite and constitutes about 80 percent of the dissolved constituents of seawater.
| atomic number | 11 |
|---|---|
| atomic weight | 22.9898 |
| melting point | 97.81 °C (208 °F) |
| boiling point | 882.9 °C (1,621 °F) |
| specific gravity | 0.971 (20 °C) |
| oxidation states | +1, −1 (rare) |
| electron configuration | 2-8-1 or 1s22s22p63s1 |
Properties and production
Because sodium is extremely reactive, it never occurs in the free state in Earth’s crust. In 1807 Sir Humphry Davy became the first to prepare sodium in its elemental form, applying electrolysis to fused sodium hydroxide (NaOH). Sodium is an important constituent of a number of silicate materials, such as feldspars and micas. There are huge deposits of rock salt in various parts of the world, and sodium nitrate deposits exist in Chile and Peru. The sodium content of the sea is approximately 1.05 percent, corresponding to a concentration of approximately 3 percent of sodium halides. Sodium has been identified in both the atomic and ionic forms in the spectra of stars, including the Sun, and the interstellar medium. Analysis of meteorites indicates that the silicate material present has an average content of approximately 4.6 atoms of sodium for every 100 atoms of silicon.
Lighter than water, sodium can be cut with a knife at room temperature but is brittle at low temperatures. It conducts heat and electricity easily and exhibits the photoelectric effect (emission of electrons when exposed to light) to a marked degree.
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Sodium is by far the most commercially important alkali metal. Most processes for the production of sodium involve the electrolysis of molten sodium chloride. Inexpensive and available in tank-car quantities, the element is used to produce gasoline additives, polymers such as nylon and synthetic rubber, pharmaceuticals, and a number of metals such as tantalum, titanium, and silicon. It is also widely used as a heat exchanger and in sodium-vapour lamps. The yellow colour of the sodium-vapour lamp and the sodium flame (the basis of an analytical test for sodium) is identified with two prominent lines in the yellow portion of the light spectrum.
Significant uses
Two of the earliest uses of metallic sodium were in the manufacture of sodium cyanide and sodium peroxide. Significant quantities were used in the manufacture of tetraethyl lead as a gasoline additive, a market that disappeared with the advent of unleaded gasoline. Substantial amounts of sodium are used in the manufacture of sodium alkyl sulfates as the principal ingredient in synthetic detergents.
Sodium also is used as a starting material in the manufacture of sodium hydride (NaH) and sodium borohydride (NaBH4). In addition, sodium is employed in the production of dyes and dye intermediates, in the synthesis of perfumes, and in a wide variety of organic reductions. It is used in the purification of hydrocarbons and in the polymerization of unsaturated hydrocarbons. In many organic applications, sodium is used in the form of dispersions in hydrocarbon liquid media.
Molten sodium is an excellent heat-transfer fluid, and, because of this property, it has found use as coolant in liquid-metal fast breeder reactors. Sodium is used extensively in metallurgy as a deoxidant and as a reducing agent for the preparation of calcium, zirconium, titanium, and other transition metals. Commercial production of titanium involves reduction of titanium tetrachloride (TiCl4) with sodium. The products are metallic Ti and NaCl.
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Principal compounds
Sodium is highly reactive, forming a wide variety of compounds with nearly all inorganic and organic anions (negatively charged ions). It normally has an oxidation state of +1, and its single valence electron is lost with great ease, yielding the colourless sodium cation (Na+). Compounds that contain the sodium anion, Na−, have also been synthesized. The principal commercial sodium compounds are the chloride, carbonate, and sulfate.
The most important and familiar sodium compound is sodium chloride, or common salt, NaCl. Most other sodium compounds are prepared either directly or indirectly from sodium chloride, which occurs in seawater, in natural brines, and as rock salt. Large quantities of sodium chloride are employed in the production of other heavy (industrial) chemicals as well as being used directly for ice and snow removal, for water conditioning, and in food.
Other major commercial applications of sodium chloride include its use in the manufacture of chlorine and sodium hydroxide by electrolytic decomposition and in the production of sodium carbonate (Na2CO3) by the Solvay process. The electrolysis of aqueous sodium chloride produces sodium hypochlorite, NaOCl, a compound of sodium, oxygen, and chlorine used in large quantities in household chlorine bleach. Sodium hypochlorite is also utilized as an industrial bleach for paper pulp and textiles, for chlorination of water, and in certain medicinal preparations as an antiseptic and a fungicide. It is an unstable compound known only in aqueous solution.
The carbonates contain the carbonate ion (CO32–). Sodium bicarbonate, also called sodium hydrogen carbonate, or bicarbonate of soda, NaHCO3, is a source of carbon dioxide and so is used as an ingredient in baking powders, in effervescent salts and beverages, and as the main constituent of dry-chemical fire extinguishers. Its slight alkalinity makes it useful in treating gastric or urinary hyperacidity and acidosis. It is also employed in certain industrial processes, as in tanning and the preparation of wool. Sodium carbonate, or soda ash, Na2CO3, is widely distributed in nature, occurring as constituents of mineral waters and as the solid minerals natron, trona, and thermonatrite. Large quantities of this alkaline salt are used in making glass, detergents, and cleansers. Sodium carbonate is treated with carbon dioxide to produce sodium bicarbonate. The monohydrate form of sodium carbonate, Na2CO3·H2O, is employed extensively in photography as a constituent in developers.
Sodium sulfate, Na2SO4, is a white crystalline solid or powder employed in the manufacture of kraft paper, paperboard, glass, and detergents and as a raw material for the production of various chemicals. It is obtained either from deposits of the sodium sulfate minerals mirabilite and thenardite or synthetically by the treatment of sodium chloride with sulfuric acid. The crystallized product is a hydrate, Na2SO4·10H2O, commonly known as Glauber’s salt. Sodium thiosulfate (sodium hyposulfite), Na2S2O3, is used by photographers to fix developed negatives and prints; it acts by dissolving the part of the silver salts coated onto film which remain unchanged by exposure to light.
Sodium hydroxide (NaOH) is a corrosive white crystalline solid that readily absorbs moisture until it dissolves. Commonly called caustic soda, or lye, sodium hydroxide is the most widely used industrial alkali. It is highly corrosive to animal and vegetable tissue. The alkaline solutions it forms when dissolved in water neutralize acids in various commercial processes: in petroleum refining, it removes sulfuric and organic acids; in soapmaking, it reacts with fatty acids. Solutions of NaOH are used in the treatment of cellulose and in the manufacture of many chemicals.
Sodium nitrate, or soda nitre, NaNO3, is commonly called Chile saltpetre, after its mineral deposits in northern Chile, the principal source. Sodium nitrate is used as a nitrogenous fertilizer and as a component of dynamite.