 Discovery Information
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| Who: Sir Humphrey Davy |
| When: 1807 |
| Where: England |
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| Name Origin
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| From soda; Na from Latin natrium. |
| "Sodium" in different languages. |
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| Sources
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| Obtained by electrolysis of melted sodium chloride (salt), borax and cryolite (Na3AlF6). Sodium makes up 2.6% by weight of the Earth's crust, making it the fourth most abundant element overall and the most abundant
alkali metal.
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| Primary producers are Germany, Poland, Kenya and the USA. 200 thousand tons of sodium metal are produced every year; salt (NaCl) around 168 million tons and sodium carbonate around
29 million tons.
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| Abundance
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| Universe: 20 ppm (by weight) |
| Sun: 40 ppm (by weight) |
| Carbonaceous meteorite: 5600 ppm |
| Earth's Crust: 23000 ppm |
| Seawater: 11500 ppm |
| Human: |
| 1.4 x 106 ppb by weight
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| 3.8 x 105 ppb by atoms
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| Uses
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| Used in medicine, agriculture and photography. Liquid sodium is sometimes used to cool nuclear reactors. Also used in street
lights, soap, batteries, table salt (NaCl) (a compound vital to life) , and glass.
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| History
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| Sodium (the English word for which is soda) has long been recognized in compounds, but was not isolated until 1807 by Sir Humphry Davy through the electrolysis of caustic soda. In medieval Europe a compound of sodium with the Latin name of sodanum was used
as a headache remedy.
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| Sodium's chemical abbreviation Na was first published by Jöns Jakob Berzelius in his system of atomic symbols (Thomas Thomson's Annals of Philosophy) and is a contraction of the element's new Latin name
natrium which refers to natron, a natural mineral salt whose primary ingredient is hydrated sodium carbonate and which historically
had several important industrial and household uses later eclipsed by soda ash, baking soda and other sodium compounds.
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| Sodium imparts an intense yellow colour to flames. As early as 1860, Kirchhoff and Bunsen noted the high sensitivity that a flame test for sodium could give.
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| Notes
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| Sodium comes from the English word "soda" and from medieval Latin sodanum which means headache remedy. Sodium is the sixth
most abundant element on earth comprising 2.6% of the earth's crust. It is the most abundant of the alkali metals. It never exists in nature, but is prepared by electrolysis of absolutely dry fused sodium chloride. Sodium chloride is common
table salt which is important in animal nutrition. Other important forms of sodium are soda ash (Na2CO3), baking soda (NaHCO3), Chili saltpeter (NaNO3) which is sodium nitrate. In nature sodium is found in soda niter, cryolite (Na3AlF6), amphibole and zeolite.
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| Sodium ions are necessary for regulation of blood and body fluids, transmission of nerve impulses, heart activity, and certain metabolic
functions. It is widely considered that most people in Western countries consume more than is needed, in the form of sodium
chloride, or table salt, and that this can have a negative effect on health.
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| Hazards
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| Sodium's metallic form is highly explosive in water and is a poison when uncombined with other elements. The powdered form
may combust spontaneously in air or oxygen. This metal should be handled carefully at all times. Sodium must be stored either in an inert atmosphere, or under a liquid
hydrocarbon such as mineral oil or kerosene.
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| The reaction of sodium and water is a familiar one in chemistry labs, and is reasonably safe if amounts of sodium smaller
than a pencil eraser are used, and the reaction is done behind a plastic shield glass by people wearing eye protection. However,
the sodium-water reaction does not scale well, and is treacherous when larger amounts of sodium are used. Larger pieces of
sodium melt under the heat of the reaction, and the molten ball of metal is buoyed up by hydrogen and appears to be stably
reacting with water until splashing covers more of the reaction mass, causing thermal runaway and an explosion which scatters
molten sodium and lye.
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| There are only a very few materials that will put out a sodium metal fire, like Pyromet and Met-L-X. Pyromet is a NaCl/(NH4)2HPO4 mix, with flow/anti-clump agents. It smoothers the fire, drains away heat, and melts to form an impermeable crust. This is
the standard dry-powder cannister fire extingusher for all classes of fires. Met-L-X is mostly just NaCl, with about 5 % Saran
as a crust-former, and a couple of flow/anti-clump agents, and is most commonly hand-applied with a scoop. There are also
other exreme fire extinguishing materials - lith-X is a graphite based dry powder with an organophosphate flame retardant,
and Na-X is a Na2CO3-based material.
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