Sodium - Na


Atomic number 11

Atomic mass 22.98977 g.mol -1

Density 0.97 -3 at 20 °C

Melting point 97.5 °C

Boiling point 883 °C

Discovered by Sir Humphrey Davy in 1807

Chemical element, symbol: Na, atomic number: 11 and atomic weight 22,9898. It’s a soft metal, reactive and with a low melting point, with a relative density of 0,97 at 20ºC (68ºF). From the commercial point of view, sodium is the most important of all the alkaline metals.

Sodium reacts quickly with water, and also with snow and ice, to produce sodium hydroxide and hydrogen. When it’s exposed to air, metallic sodium recently cut looses its silvery appearance and acquires an opaque grey colour due to the formation of a sodium oxide coating. Sodium doesn’t react with nitrogen , not even at very high temperatures, but it can react with ammonia to form sodium amide. Sodium and hydrogen react above 200ºC (390ºF) to form sodium hydride. Sodium hardly reacts with carbon , but it does react with halogens. It also reacts with various metallic halides to form the metal and sodium chloride. Sodium doesn’t react with paraffinic hydrocarbons, but it forms addition compounds with naphthalene and other aromatic polycyclic compounds and with aryl alkenes. The reaction of sodium with alcohols is similar to the reaction of sodium with water, but slower. There are two general reactions with organic halides. One of them requires the condensation of two organic compounds, which form halogens when those are eliminated. The second type of reaction includes the replacement of halogen by sodium, to obtain a sodium organic compound.


Sodium in its metallic form is very important in making esters and in the manufacture of organic compounds. Sodium is also a component of sodium chloride (NaCl) a very important compount found everywhere in the living environment. Other uses are: to improve the structure of certain alloys; in soap, in combination with fatty acids, in sodium vapor lamps, to descal metals, to purify molten metals.

Solid sodium carbonate is needed to make glass.

Sodium in the enviornment

Sodium is the sixth most abundant element in The Earth’s crust, which contains 2,83% of sodium in all its forms. Sodium is, after chloride, the second most abundant element dissolved in seawater. The most important sodium salts found in nature are sodium chloride (halite or rock salt), sodium carbonate (trona or soda), sodium borate (borax), sodium nitrate and sodium sulfate. Sodium salts are found in seawater (1.05%), salty lakes, alkaline lakes and mineral spring water .

The production of salt is around 200 million tonnes per year; this huge amount is mainly extracted from salt deposits by pumping water down bore holes to dissolve it and pumping up brine.

The sun and many other stars shine with visible light in which the yellow component dominates and this is given out by sodium atoms in a high-energy state.

Health effects of sodium

Sodium is a compound of many foodstuffs, for instance of common salt. It is necessary for humans to maintain the balance of the physical fluids system. Sodium is also required for nerve and muscle functioning. Too much sodium can damage our kidneys and increases the chances of high blood pressure.

The amount of sodium a person consumes each day varies from individual to individual and from culture to culture; some people get as little as 2 g/day, some as much as 20 grams. Sodium is essential, but controversely surrounds the amount required.

Contact of sodium with water, including perspiration causes the formation of sodium hydroxide fumes, which are highly irritating to skin, eyes, nose and throat. This may cause sneezing and coughing. Very severe exposures may result in difficult breathing, coughing and chemical bronchitis. Contact to the skin may cause itching, tingling, thermal and caustic burns and permanent damage. Contact with eyes may result in permanent damage and loss of sight.

Environmental effects of sodium

odium's powdered form is highly explosive in water and a poison combined and uncombined with many other elements.

Ecotoxicity: Median tolerance limit (TLM) for the mosquito fish, 125 ppm/96hr (fresh water); Median tolerance limit (TLM) for the bluegill, 88 mg/48hr (tap water).

Environmental fate: this chemical is not mobile in solid form, although it absorbs moisture very easily. Once liquid, sodium hydroxide leaches rapidly into the soil, possibly

For billions of years sodium is washed out from rocks and soils, ending up in oceans, where it may remain for about 50.106 years. Seawater contains approximately 11,000 ppm sodium. Rivers contain only about 9 ppm.

Drinking water usually contains about 50 mg/L sodium. This value is clearly higher for mineral water. In soluble form sodium always occurs as Na+ ions.

In what way and in what form does sodium react with water?

Elementary sodium reacts strongly with water, according to the following reaction mechanism:

2Na(s) + 2H2O → 2NaOH(aq) + H2(g)

A colourless solution is formed, consisting of strongly alkalic sodium hydroxide (caustic soda) and hydrogen gas. This is an exothermic reaction. Sodium metal is heated and may ignite and burn with a characteristic orange flame. Hydrogen gas released during the burning process reacts strongly with oxygen in the air.

A number of sodium compounds do not react as strongly with water, but are strongly water soluble.

A number of examples of water solubility of sodium are available. De most familiar sodium compounds is sodium chloride (NaCl), otherwise known as kitchen salt. At 20oC solubility is 359 g/L, in other words adequately water soluble. Solubility is nearly temperature independent. Sodium carbonate (Na2CO3) is also adequately water soluble. Solubility is 220 g/L at 20oC.

Sodium compounds naturally end up in water. As was mentioned earlier, sodium stems from rocks and soils. Not only seas, but also rivers and lakes contain significant amounts of sodium. Concentrations however are much lower, depending on geological conditions and wastewater contamination.

Sodium compounds serve many different industrial purposes, and may also end up in water from industries. They are applied in metallurgy, and as a cooling agent in nuclear reactors. Sodium nitrate is often applied as a synthetic fertilizer.

About 60% of sodium is utilized in chemical industries, where it is converted to chlorine gas, sodium hydroxide or sodium carbonate, and about 20% of sodium is utilized in food industries as a preservative or a flavouring agent. The remainder is applied for example as brine in winter.

Sodium hydroxide may be applied to prevent clogging of sewer pipes, and sodium carbonate is applied in water purification to neutralize acids. Sodium hydrogen carbonate is a constituent of backing powder, and is applied in textile and leather industries and in soap and cleanser production. In sanitary cleanser the element is present as sodium hypo chlorite.

Using sodium metal, beryllium, thorium, titanium and zirconium can be extracted. In lamppost lights a small portion of sodium is often present in the neon lights, causing them to use fewer electricity.

The radioactive isotope 24Na is applied in medical research.

Sodium is attributed water hazard class 2, in other words it is a risk when present in water. Sodium chloride however is not a risk and is attributed water hazard class 1.

Sodium is a dietary mineral for animals. Plants however hardly contain any sodium. The LC50 value for gold fish is 157 mg/L. Sodium hypo chlorite from sanitary cleansers may contribute to chlorinated hydrocarbon formation, and may therefore heavily charge wastewater.

Only one sodium isotope occurs naturally, namely the stable 23Na. There are 13 instable sodium isotopes, which are mildly radioactive.

Sodium is present in the human body in amounts of about 100 g. It is a dietary mineral, partially responsible for nerve functions. Blood serum contains 3.3 g/L sodium. It regulates extra cellular fluids, acid-base balance and membrane potential, partially together with potassium .

One may overdose on sodium from kitchen salt. This causes increased blood pressure, arteriosclerosis, oedema, hyperosmolarity, confusion and increased risk of infection from excessive Na+ intake. Sodium shortages may lead to dehydration, convulsion, muscle paralysis, decreased growth and general numbness.

Generally, humans require about 300 mg sodium chloride per day to warrant a balanced sodium level. People that have diarrhoea or other health effects that increase salt requirements need a higher dietary amount of sodium than usual. Adult intake of kitchen salt is on average 9 g per day, which translates to approximately 4 g of sodium. People with heart and kidney disease are recommended a sodium poor diet.

Kitchen salt solution was applied as vomiting provoker in the old days. Caustic soda can deeply affect tissues.

To remove sodium chloride from water, one may apply reverse osmosis , electro dialysis , distillation techniques or ion exchange . Reverse osmosis is most economical considering energy and money requirements.

Sodium is applied in water purification. It may function as a counter ion of calcium and magnesium in water softeners . Caustic soda and sodium per carbonate are applied to neutralize acids. Sodium bisulphite (NaHSO3) is applied as a reductor for strongly oxidizing chemicals, sodium sulphide (Na2S) for precipitation of complexed metals.

Richard Orberson Designed this12/29/2017