Sodium [Na]

Characteristics

An: 11 N: 12
Am: 22.989770 g/mol
Group No: 1
Group Name: Alkali metal
Block: s-block Period: 3
State: solid at 298 K
Colour: silvery white Classification: Metallic
Boiling Point: 1156K (883oC)
Melting Point: 370.87K (97.27oC)
Critical temperature: 2573K (2300oC)
Density: 0.968g/cm3

Discovery Information

Who: Sir Humphrey Davy
When: 1807
Where: England

Name Origin

From soda; Na from Latin natrium. "Sodium" in different languages.

Sources

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.
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.

Abundance

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; 3.8 x 105 ppb by atoms

Uses

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.

History

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.
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.
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.

Notes

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.
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.

Hazards

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.
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.
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.

Sodium Compounds

Borax Na2B4O7 - 10H2O

It is a soft white many-sided crystal that dissolves easily in water.
is widely used in detergents, water softeners, soaps, disinfectants, and pesticides. Its use in detergents is due to its ability to bind to and solvate dirt particles in addition to producing peroxides which have a bleaching effect. One of its most widely advertised uses was as a hand-cleaner for industrial workers. It is used in making enamel glazes, glass and strengthening pottery and ceramics. It is also easily converted to boric acid or borate, which have many applications. It is also used to make buffer solutions that are used in chemical analysis.
Large amounts of borax pentahydrate (Na2B4O7 - 5H2O) are used for manufacturing insulating fibreglass and cellulose insulation as a fire retardant and anti-fungal compound. Large amounts are also used in production of sodium perborate monohydrate for use in detergents.

Disodium guanylate(E627) C10H14N5O8P

A food additive used as a flavour enhancer, derived from dried fish or dried seaweed. It is found in instant noodles, crisps (potato chips) and snacks, savoury rice, tinned vegetables, cured meats, packet soup.

Monosodium methyl arsenate CH4AsNaO3 : Toxic :

An arsenic-based herbicide and fungicide, one of the most common herbicides used on golf courses.

Sodium benzoate (E211) C6H5COONa

As a food additive it is used as a preservative, effectively killing most yeasts, bacteria and fungi. Sodium benzoate is effective only in acidic conditions (pH less than 3.6) making its use most prevalent in foods such as preserves, salad dressings (vinegar), carbonated drinks (carbon dioxide), jams (citric acid), fruit juices (citric acid), and chinese food sauces (soy, mustard, and duck). It is also found in alcohol-based mouthwash. More recently, sodium benzoate has become apparent in many soft drinks, including Sprite, Sunkist and Dr Pepper.
It is found naturally in cranberries, prunes, greengage plums, cinnamon, ripe cloves, and apples.

Sodium bicarbonate NaHCO3 : Irritant :

Also known as sodium hydrogen carbonate, baking soda, bread soda and bicarbonate of soda.
It is used as an antacid to treat acid indigestion and heartburn. The anhydrous form is also used to absorb moisture and odours; an open box can be left in a refrigerator for this purpose. However, baking soda does not actually absorb odors well when used in a refrigerator.
When used in toothpaste, baking soda helps to gently remove stains, whiten teeth, freshen breath, and dissolve plaque.
It is commonly used to increase the pH and total alkalinity of the water for pools and spas. Sodium bicarbonate can be added as a simple solution for restoring the pH balance of water that has a high level of chlorine.
It also has military applications. Cold sodium bicarbonate can be used to stop the chemical agent White Phosphorus, a common allotrope of phosphorus often used in incendiary bullets, from spreading inside a soldier’s afflicted wounds.

Sodium carbonate Na2CO3

Used in the manufacture of glass, pulp and paper, detergents, and chemicals such as sodium silicates and sodium phosphates.
It is used as a water softener during laundry. It competes with the ions magnesium and calcium in hard water and prevents them from bonding with the detergent being used. Without using washing soda, additional detergent is needed to soak up the magnesium and calcium ions. Called washing soda in the detergent section of stores, it effectively removes oil, grease, and alcohol stains.
When used in toothpaste, baking soda helps to gently remove stains, whiten teeth, freshen breath, and dissolve plaque.
Sodium carbonate is widely used in photographic processes as a pH regulator to maintain stable alkaline conditions necessary for the action of the majority of developing agents, it is also used by the brick industry as a wetting agent to reduce the amount of water needed to extrude the clay.

Sodium Chloride NaCl

Sodium chloride, also known as common salt, table salt, or halite. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms.
It is essential to life on Earth. Most biological tissues and body fluids contain a varying amount of salt. The concentration of sodium ions in the blood is directly related to the regulation of safe body-fluid levels. Propagation of nerve impulses by signal transduction is regulated by sodium ions. (Potassium, a metal closely related to Sodium, is also a major component in the same bodily systems).

Sodium citrate Na3C6H5O7

Is chiefly used as a food additive, usually for flavour or as a preservative. Sodium citrate is common in lemon-lime soft drinks, and it is partly what causes them to have their sour taste.

Sodium cyanide NaCN : Highly Toxic :

Like the similar potassium cyanide, NaCN has a smell like bitter almonds, but not everyone can smell it.
Sodium cyanide is used to extract gold and other precious metals from ore, and so metal mining operations consume most of the sodium cyanide production. Sodium cyanide is illegally used to collect fish. Accidents with cyanide solutions are a severe danger to aquatic ecosystems.
Cyanide salts are among the most rapidly acting of all known poisons. Cyanide is a potent inhibitor of respiration.


Sodium dodecyl sulfate CH3(CH2)11OSO3Na

Also known as sodium lauryl sulfate (SLS), is an ionic surfactant that is used in household products such as toothpastes, shampoos, shaving foams and bubble baths for its thickening effect and its ability to create a lather.
Like all detergent surfactants (including soaps), it removes oils from the skin, and can cause skin irritation. It is also irritating to the eyes.
It is suspected that SLS is linked to a number of skin issues such as dermatitis, and when combined with certain chemicals, SLS may become a carcinogen.

Sodium fluoride NaF

Once used to fluoridate water, an ingredient in toothpaste that prevents cavities.

Sodium iodide NaI

Sodium iodide is commonly used to treat and prevent iodine deficiency. Solid crystals can be used to detect radiation (e.g. radiation from uranium) - a solid crystal of sodium iodide creates a pulse of light when radiation interacts with it.

Sodium hypochlorite NaOCl

A solution of sodium hypochlorite is frequently used as a disinfectant and as a bleaching agent; indeed, often it is simply called "bleach", though other chemicals are sometimes given that name as well.

Sodium metabisulfite Na2S2O5

It is used as a food additive, mainly as a preservative and is sometimes identified as E223. As an additive, it may cause allergic reactions, particularly skin irritation, gastric irritation and asthma. It is not recommended for consumption by children.
It is commonly used in homebrewing preparations to sanitize equipment.

Sodium monofluorophosphate Na2PO3F

Best known as an ingredient in toothpastes for both humans and animals. It is claimed to protect tooth enamel from attack by bacteria that cause dental caries (cavities). Though developed by a chemist at Procter and Gamble, its use in toothpaste (Colgate toothpaste) was patented by Colgate-Palmolive, as Procter and Gamble was engaged in the marketing of Crest toothpaste (containing stannous fluoride).
It is also used in some medications for the treatment of osteoporosis.

Sodium nitrate NaNO3

Best known as an ingredient in toothpastes for both humans and animals. It is claimed to protect tooth enamel from attack by bacteria that cause dental caries (cavities). Though developed by a chemist at Procter and Gamble, its use in toothpaste (Colgate toothpaste) was patented by Colgate-Palmolive, as Procter and Gamble was engaged in the marketing of Crest toothpaste (containing stannous fluoride).
It can be used in the production of nitric acid by combining with sulfuric acid and subsequent separation through fractional distillation of the nitric acid, leaving behind a residue of sodium bisulfate.

Sodium nitrite NaNO2

As a food additive, it serves a dual purpose in the food industry since it both alters the colour of preserved fish and meats and also prevents growth of Clostridium botulinum, the bacteria which causes botulism. In the European Union it may be used only as a mixture with salt containing at most 0.6 % sodium nitrite. It has the E number E250.
Various dangers of using this chemical as a food additive have been suggested and researched by scientists, although no conclusive evidence has been put forth. A principal concern is the formation of carcinogenic N-nitrosamines by reaction with sodium nitrite; other ingredients are often added to prevent nitrosamine-generating reactions.
Sodium nitrite also has been used in human and veterinary medicine as a vasodilator, a bronchodilator, an intestinal relaxant or a laxative, and an antidote for cyanide poisoning.

Sodium persulfate Na2S2O8 : Irritant :

It is used as a bleach, both standalone (particularly in hair cosmetics) and as a detergent component. It is a replacement for ammonium persulfate in etching mixtures for zinc and printed circuit boards, and is used for pickling of copper and some other metals. It is a source of free radicals, making it useful as an initiator for eg. emulsion polymerization reactions and for accelerated curing of low formaldehyde adhesives. It is also used as a soil conditioner and in manufacture of dyestuffs, modification of starch, bleach activator, desizing agent for oxidative desizing.

Sodium propionate Na(C2H5COO)

Used as a mold inhibitor in bakery products.

Sodium pyrophosphate Na(C2H5COO) [ Mildly Toxic : Mild Irritant ]

Sodium pyrophosphate is used as a buffer, an emulsifier, and a thickening agent, and is often used as a food additive. Common foods containing sodium pyrophosphate include chicken nuggets, marshmallows, crab meat, imitation crab, and soy-based meat alternatives.
In toothpaste, sodium pyrophosphate acts as a tartar control agent, serving to remove calcium and magnesium from saliva and thus preventing them from being deposited on teeth. Sodium pyrophosphate is sometimes used in household detergents to prevent similar deposition on clothing, but due to its phosphate content it causes eutrophication of water, promoting algae growth.

Sodium selenite Na2Se2 : Toxic :

It is a source of selenium in many food supplements. Although selenium is poisonous, it should be noted that selenium is essential in small amounts. Humans and animals require selenium for the function of a number of selenium-dependent enzymes, also known as selenoproteins.

Sodium silicoaluminate

Anticaking agent added to various products including table salt and other food products, powders, and house paints to prevent the formation of large crystals or lumps.

Sodium stearate C17H35COONa

The major component of soap.

Sodium sulfite Na2SO3

It is primarily used in the pulp and paper industry. It is used in water treatment as an oxygen scavenger agent, in the photographic industry to protect developer solutions from oxidation and (as hypo clear solution) to wash fixer (sodium thiosulfate) from film and photo-paper emulsions, in textile industry as a bleaching, as a desulfurizing and as a dechlorinating agent and in leather trade for the sulfitization of tanning extracts.
It is also used as a preservative to prevent dried fruit from discolouring, and for preserving meats.

Sodium thiopental C11H17N2NaO2S

Thiopental is an ultra-short acting barbiturate and is most commonly used in the induction phase of general anesthesia. Following intravenous injection the drug rapidly reaches the brain and causes unconsciousness within 30-45 seconds. At one minute, the drug attains a peak concentration of about 60% of the total dose in the brain. Thereafter, the drug distributes to the rest of the body and in about 5-10 minutes the concentration is low enough in the brain such that consciousness returns.
Along with pancuronium bromide and potassium chloride, thiopental is used in 37 states of the US to execute prisoners by lethal injection. A megadose is given which places the patient into a rapidly induced coma. Executions using the three drug combination are usually effective in approximately 10 minutes, but have been known to take several times this length. The use of thiopental alone is hypothesized to cause death in approximately 45 minutes.
Thiopental is still used in some places as a truth serum. The barbiturate drugs as a class decrease higher cortical brain functioning. Psychiatrist hypothesize that lying is more complex than the truth, suppression of the higher cortical functions may lead to the uncovering of the "truth" since the "truth" would theoretically be less complex.

Sodium thiopental Na5P3O10

It is used in various applications such as a preservative for seafood, meats, poultry and pet foods. It is also used in toothpaste and as a builder in soaps and detergents, improving their cleansing ability.

Reactions of Sodium

Reactions with water
Sodium metal reacts rapidly with water to form a colourless solution of sodium hydroxide and hydrogen gas. The is an exothermic reaction, the sodium metal may well become so hot that it catches fire and burns with a characteristic orange colour. The reaction is slower than that of potassium but faster than that of lithium.
2Na(s) + 2H2O(l) --> 2NaOH(aq) + H2(g)
Reactions with air
The shiny surface of sodium soons becomes dull due to the reaction of air and moisture. When sodium is burnt in air the result is white sodium peroxide together with some white sodium oxide.
2Na(s) + O2(g) --> 2Na2O(s)
4Na(s) + O2(g) --> 2Na2O2(s)
Reactions with halogens
Sodium reacts vigorously with all halogens to form sodium halides.
2Na(s) + F2(g) --> NaF(s)
2Na(s) + Cl2(g) --> NaCl(s)
2Na(s) + Br2(g) --> NaBr(s)
2Na(s) + I2(g)--> NaI(s)
Reactions with acids
Sodium readily dissolves in dilute sulphuric acid to form a solution containing the Na(I) ion and hydrogen gas.
2Na(s) + H2SO4(aq) --> 2Na+(aq) + SO42-(aq) + H2(g)
Reactions with bases
Sodium metal reacts rapidly with water to form a colourless solution of sodium hydroxide and hydrogen gas. The is an exothermic reaction, the sodium metal may well become so hot that it catches fire and burns with a characteristic orange colour. The reaction is slower than that of potassium but faster than that of lithium.
2Na(s) + 2H2O(l) --> 2NaOH(aq) + H2(g)

Occurrence of Sodium

At the end of the 19th century, sodium was chemically prepared by heating sodium carbonate with carbon to 1100°C.
Na2CO3 (liquid) + 2C(solid, coke) --> 2Na(vapour) + 3CO(gas)
It is now produced commercially through the electrolysis of liquid sodium chloride. This is done in a Downs Cell in which the NaCl is mixed with calcium chloride to lower the melting point below 700oC. As calcium is less electronegative than sodium, no calcium will be formed at the cathode. This method is less expensive than the previous Castner process of electrolyzing sodium hydroxide.
Very pure sodium can be isolated by thermal decomposition of sodium azide (NaN3).

Isotopes of Sodium

22Na [11 neutrons]
Abundance: synthetic
Half life: 2.602 years [ beta+ ]
Decay Energy: 0.546 MeV
Decays to 22Ne.
Half life: 2.602 years [ Electron Capture ]
Decay Energy: ? MeV
Decays to 22Ne.
Half life: 2.602 years [ Gamma Radiation ]
Decay Energy: 1.2745 MeV
Decays to ?. 

23Na [12 neutrons]
Abundance: 100%
Stable with 12 neutrons
Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable 23Na in human blood plasma to 24Na. By measuring the concentration of this isotope, the neutron radiation dosage to the victim can be computed.
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