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Sodium is a frequently occurring chemical element with the symbol Na and atomic number 11 in the periodic table of elements, it is in the 3rd period and the alkali metal in the first group or main group 1. Sodium is a pure element, whose only stable isotope is 23Na.

Elemental sodium was first won in 1807 by Humphry Davy by electrolysis of sodium hydroxide and called Sodium. This term is, inter alia, in the English and French speaking countries used derivatives thereof in the Romanesque and partly also in the Slavic languages. The German name "sodium" is the Arabic ناترون "Natrun", "soda", derived from the Egyptian "netjerj". Sodium and derivatives thereof are except in the German language including in Scandinavia, the Netherlands and some Slavic languages ​​in use.

Under normal conditions, sodium is a growing soft, silvery, highly reactive metal. Because of its reactivity metallic (elemental) Sodium is stored under inert conditions, mostly in paraffin oil or kerosene, in larger quantities in airtight steel drums.

Sodium is one of the ten most common elements in the earth’s crust and comes in numerous sodium-containing minerals in the land and seabed. Also in the oceans, a significant amount of sodium (as Ion) is included.

The Egyptians coined in antiquity for the product obtained from soda lakes soda the term netjerj (neter). The Greeks adopted this word as Greek νίτρον = nitrone, the Romans as Nitrium, the Arabs as Natrun. sodium compounds have been known for a long time as opposed to elemental metal and have since been obtained from sea water or lakes, mined from Erdlagerstätten and traded. The most important compound of sodium salt (sodium chloride) was in mines won or by drying of sea water or saline spring water in salt pans. The salt trade was for many cities the basis of their wealth, and sometimes even coined its name (Salzgitter, Salzburg). In the Germanic name for saline (Hall) have names like Hallstatt, Hallein, Halle (Saale), Bad Hall, Bad Reichenhall, Schwäbisch Hall, Swiss Hall or Hall back in Tyrol. Other naturally occurring sodium compounds such as sodium (Soda or baking soda) and sodium nitrate were recovered and traded since ancient times.

The production of elemental sodium was achieved only in 1807 Humphry Davy by electrolysis of molten sodium hydroxide (caustic soda) using voltaic column as a power source. As he reported on November 19, 1807 at the Royal Society in London, he won two different metals: he called the sodium contained in Soda Sodium, which is still in use today Identification of the metal in the French and English speaking countries; the other metal he called Potassium (potassium). Berzelius suggested in 1811 the present name of sodium.

In the universe sodium is in the incidence in 14th place, similar to calcium and nickel. The emitted light of many celestial bodies, even that of the sun, the yellow sodium D line can be detected well.

On Earth, sodium with a proportion of the earth’s crust of 2.36%, the sixth most common element. It is due to its reactivity not elementary, but always in compounds, the sodium salts before. A great memory of sodium is the sea water. One liter of seawater contains an average of 11 grams of sodium ions.

Common sodium minerals are albite, also called sodium feldspar, and oligoclase NaAlSi3O8 (Na, Ca) Al (Si, Al) 3o8. In addition to these rock-forming minerals, which are among the feldspars, sodium is found in large salt deposits. There are especially large deposits of halite (sodium chloride, colloquially often called halite) that are created by the drying of marine parts. These represent the most important source for the production of sodium and its Known compounds dar. German salt production sites include Salzgitter, Bad Reichenhall, Bad Stade and Frederick Hall.

In addition to sodium chloride and other sodium salts in nature occur. Thus, sodium nitrate or sodium nitrate (also called Chile saltpetre) NaNO3 one of the few natural nitrate minerals. It is because of its high water solubility, but only in very dry areas, such as the Atacama Desert in Chile before. Before the invention of the Haber-Bosch process was the most important raw material for many fertilizer and explosives.

Sodium carbonate Na2CO3 is also found naturally in several minerals. The most common mineral is soda Na2CO3 · 10 H2O. It degrades in large quantities and mainly used in the manufacture of glass.

In addition, there are also a variety of other minerals sodium (see also: Category: sodium mineral). A well-known is the cryolite (Eisstein, Na3 ), which serves as a solvent for aluminum oxide in the production of aluminum in a molten state. Since the only known cryolite deposit was mined in Greenland, cryolite is now produced artificially.

Sodium is mainly produced from sodium chloride, which is usually obtained by mining or by desiccation of saline solutions such as seawater. Only a small portion of the sodium chloride is further processed to elemental sodium, the largest part will be used as table salt, or for the preparation of other sodium compounds.

The large scale production of sodium takes place today by electrolysis of dry sodium chloride in a so-called cell-Downs (1924 patented by James C. Downs). In order to reduce the melting point eutectic salt mixture of 60% calcium chloride and 40% sodium chloride is used, which melts at 580 ° C. Also barium chloride is possible as an addition. There is applied a voltage of approximately seven volts. For the production of a Kg sodium during the electrolysis consumes about 10 kWh of electricity, the entire production process about 12 kWh.

The cylindrical electrolytic cell comprises a central anode of graphite and a lateral cathode ring made of iron. Above the cell is a bell, which collects and discharges the resultant chlorine. The sodium is collected above the cathode, and is removed by a chilled riser from the cell. Also arisen calcium crystallized from there, and fall back into the melt.

Electrolysis of sodium chloride replaced the Castner method. Here, the sodium was obtained by electrolysis of sodium hydroxide. Although this had the advantage of lower melting point of sodium hydroxide (318 ° C), but it will require more electrical energy. Since the introduction of chlor-alkali igneous electrolysis, the price of sodium has been reduced drastically. This sodium is by volume the cheapest light metal at all. The Price, however, depends heavily on the cost of electricity and the price of the coproduct chlorine.

Sodium is a silver-white, soft light metal. In many properties, it is between lithium and potassium. Thus, the melting point is at 97.82 ° C between the lithium (180.54 ° C) and potassium (63.6 ° C). Similarly, this is at the boiling point and specific heat capacity. With a density of 0.968 g · cm-3 Sodium is one of the specifically lightest elements. Among the solid at room temperature elements have only Lithium and potassium, a lower density. With a Mohs hardness of 0.5 sodium is so soft that it can be cut with a knife.

Sodium crystallizes as the other alkali metals, in the cubic crystal system in a body-centered lattice with the space group and two formula units per unit cell. Below 51 K it goes into a hexagonal close packing with lattice parameters a = 376 pm and c = 615 pm over.

Sodium vapor comprises both the individual metal atoms, as well as dimers of the form Na 2. At the boiling point are 16% of the atoms as a dimer. The vapor is yellow and appears in phantom purple.

With potassium liquid mixtures are formed over a wide range of concentrations at room temperature. The phase diagram shows an incongruent melting at 7 ° C Na2K connection and a eutectic at -12.6 ° C with a potassium content of 77% (mass fraction).

Like the other alkali metals, sodium is a very non-noble element (normal potential: -2.71 V ) and reacts readily with many other elements, and partly also with connections. The reactions are mainly concerned with non-metals such as chlorine or sulfur, very violent and run under a bright yellow flame appearance.

The otherwise reactive oxygen provides a special dar. sodium and oxygen react without the presence of water at room temperature and when heating is not directly connected. Under a completely anhydrous sodium oxygen atmosphere can even be melted without a reaction takes place. By contrast, if traces of moisture present, it burns easy to sodium peroxide.

With water react to form sodium hydrogen to sodium hydroxide. In alcohols to sodium implements the formation of hydrogen to sodium alcoholates. Due to the high heat of reaction is often melts. In a fine distribution of the sodium and the resulting large reaction surface, the reaction may be explosive and ignite the hydrogen. Is sodium chlorinated compounds such as dichloromethane, chloroform, carbon tetrachloride into contact comes is the formation of sodium chloride in a rapid and exothermic reaction.

Sodium dissolves with blue staining in liquid ammonia. The color is due to the free electrons, which are emitted from the sodium in the solution. So passing the solution also electricity and diluted paramagnetic. In a similar manner, (2.2.2-cryptand) can also be the anion of sodium, the Natrid ion, for example in the form of potassium represent natrids (K + (C222) Na). It is a very strong reducing agent.

From a total of 15 sodium isotopes and 2 more Kernisomere of 18Na to 33Na are known. Of these, only one comes, the isotope 23Na naturally. Thus, sodium is one of 22 pure elements. The longest-lived artificial isotopes 22Na, which merges with a half-life of 2,602 years of beta decay in 22Ne and 24Na, which with a half-life of 14.959 hours also decays by beta decay to 24Mg. These are used as tracers used in nuclear medicine. All other isotopes and isomers have short half-lives of seconds or milliseconds.

Large amounts of sodium chloride and other sodium compounds such as sodium carbonate promoted. Of which only a very small fraction is further processed to sodium. Most of it is used directly or converted to other compounds. About uses of sodium compounds: see section connections.

Sodium is the most widely used alkali metal. It is also used in the laboratory for various purposes, both technically. From one part of sodium a number of sodium compounds is prepared. These are for example the sodium peroxide used as a bleaching agent and the strong base sodium amide. These do not occur naturally and can not be recovered directly from sodium chloride. Also, sodium cyanide and sodium hydride prepared from sodium. Since sodium the solidification structure affected, it can be used as an additive in aluminum-silicon alloys (refining process as Aladar Pacz).

Sodium catalyzes the polymerization of 1,3-butadiene and isoprene. Therefore, it was used for the production of synthetic rubber. with sodium as a catalyst obtained plastic which has been referred to as Buna, was the first synthetic rubber in the world. From 1937 he was in the Buna-Werke (named after butadiene and sodium) produced in Schkopau.

As sodium with a thermal conductivity of 140 W/m · K, which is far higher than that of steel (15 to 58 W/m · K), good heat transfer characteristics and also a low melting point has at the same time a large liquid range, it is used as a cooling agent cooling of the thermally highly stressed exhaust valves in internal combustion engines. For this purpose, the valve stems to be made hollow and filled partly with sodium. In operation, the sodium melts and spills between the hot and cold sides back and forth. The heat is carried away by the glowing red hot valve plate.

Even fast breeder reactors are cooled with molten sodium. In such breeder reactors that produced during the nuclear fission fast neutrons can not be slowed down, as in other types of reactors between the fuel rods. It may therefore be used for cooling, no water, as the braking means (moderator) looks, be used. The heat is then transferred via a secondary sodium circuit to the steam generator for the turbine operation.

Sodium vapor lamps use of the characteristic yellow light, the sodium vapor emits light when an electric discharge. They are often used because of their high light output for street lighting.

Some metals, such as titanium, zirconium, tantalum or uranium can not be obtained by reduction with carbon because this stable and non-separable carbides occur. In addition to some other elements, particularly aluminum and magnesium, therefore sodium is used as the reducing agent. A further element to the presentation sodium is used is potassium. Since potassium is a very non-noble element, it can not be obtained by reduction with carbon. A theoretically possible production by electrolysis is not technically possible due to the high solubility of potassium in potassium chloride melt.

Sodium plays an important role as the reducing agent in the organic synthesis. For a long time the most important technical sodium application was the production of tetraethyl lead from chloroethane. This was an important anti-knock agent that was added to gasoline. For environmental reasons, the use of tetraethyl lead was severely restricted or banned altogether. Therefore, the consumption decreased in sodium. In other reactions, such as the Birch reduction and the Pinacol coupling is used sodium. However, these are more likely in the lab-scale of interest.

Since sodium reacts with traces of water, freshly pressed sodium wire can be used as a desiccant for drying organic solvents such as diethyl ether or toluene. This method is not suitable because sodium reacts violently with these: For halogenated solvents (methylene chloride, chloroform examples).

Sodium-potassium alloys, are liquid at room temperature. These are used for heat transfer and for dehalogenation in organic synthesis. Na-K works well to dry some already well pre-dried solvent to achieve very low residual water contents.

The qualitative detection and quantitative determination carried atomspektroskopisch by the intense yellow flame color, or more precisely on the Na-double line at 588.99 nm and 589.59 nm

The detection of sodium in a purely chemical way is very difficult. Since almost all sodium compounds are readily soluble in water, conventional precipitation reactions and gravimetric analysis are hardly possible. Exceptions are the yellow Natriummagnesiumuranylacetat NaMg (UO2) 3 (CH3COO) 9.9 H2O and the colorless Natriumhexahydroxoantimonat Na, both of which are soluble. A precipitation reaction with the sulfate-bismuth Doppelsaz 3Na2SO4 * 2Bi2 (SO4) 3 * 2H2O is also possible.

Also color reactions are difficult because sodium ions are colorless in aqueous solution. Are of practical importance today, therefore, in addition to the ion chromatography, only the spectroscopic methods.

Sodium is one of the elements that are essential for all animal organisms. In the animal organism is sodium – along with chlorine – the ninth most abundant element and is – according to calcium and potassium – the third most abundant inorganic ion. It is thus one physiologically to the amount of elements. Sodium is present in living organisms in the form of Na + ions.

In the human body is about 100 g of sodium are for an average body weight of 70kg or above as Na + ions. Of these, two-thirds and one-third as NaCl as before NaHCO3. Since it constitutes 90% of the extracellular electrolytes in the human body determines the sodium concentration on the vessel volume and the volume of the interstitial fluid.

The estimated value for the minimum intake of sodium is, according to the DA-CH reference values ​​at 550 mg/day for adults by various organizations but there are particular recommendations for a maximum intake of sodium (WHO. 2 g/day ; AHA: 1.5 g/day ).

The actual daily sodium intake is often higher than these values. The reason for this is our relatively high salt consumption (2.5 grams of salt contain about 1 g sodium). The National Nutrition Survey II (NVS II) of the Max Rubner-Institut, in which the sodium consumption was determined on the basis of questionnaires resulted in a median intake of 3.2 g/day (men) or 2.4 g/day (women). Presumably, the actual sodium intake is still higher because the collection via questionnaires is prone to error. The "gold standard" for the determination of sodium intake is the determination of sodium in 24-hour urine. A report by the WHO, sodium excretion (men) or 2.7-3.5 g/day was in the INTER-SALT study in various places in Germany at 4.1-4.5 g/day (women).

The sodium content is strictly controlled and is closely associated with the regulation of water balance. The normal concentration of sodium in serum is approximately 135-145 mmol/l If the sodium levels low is spoken of hyponatremia in which there is an increase in cell volume. In a hypernatremia, however, the sodium level is too high and the cells shrink. In both cases mainly the function of the brain is affected. It can to epileptic seizures and altered consciousness leading to coma. An important role for the regulation play the renin-angiotensin-aldosterone system, antidiuretic and atriopeptin.

Key organ in the regulation of sodium is the kidney. This is responsible for water to hold back, to dilute the sodium in the body at a excess sodium and excrete sodium itself. In a sodium-depleted water is increased secretion and sodium retiniert. However, it should be noted that the kidney takes some time before they can respond to the altered sodium component.

In the organism, the Na + ions are not evenly distributed, but rather are – the concentrations differ greatly within and outside the cells – as with the other ions as well. This concentration gradient of Na + – and Cl – (mostly outside), K + – and organic anions (mostly inside) cause the majority of the membrane potential of living cells. This membrane potential and ion gradients are vital for most cells. Since the small inorganic ions continuously migrate into the neighboring area because of the differences in concentration, it requires an active process that counteracts the. The most important role is played by the sodium-potassium pump, the energy consumption under Na + -. Pumps it back again and again and K + ions

Na + ions play an important role in the origin and transmission of impulses in nerve cells (and muscle). There are certain receptors after their activation by transmitter substances (neurotransmitters) that are released from the preceding nerve cell when they are energized, open and become permeable to sodium ions at the post synaptic nerve cells (and at the neuromuscular end plate of the muscle fibers). By sodium influx there is a local change of the stable ground state of the cell membrane potential. The interior is from the exterior less negative, it is called a depolarization. If this depolarization after the way up to the axon still strong enough, in the opening of another sodium channel type. It is the voltage-dependent sodium channels of the axon, the local depolarization – together with other ion channels – through a particular Forward opening and closing rhythm. Thus, a continuous voltage waveform, the action potential in the axon of the nerve cells. In recovery of the ground state, in turn, the sodium-potassium pump plays an essential role.

In plants, however, sodium plays a subordinate role. While potassium for all plants and most microorganisms is essential, sodium is only needed by some C4 and CAM plants, C3 plants generally are not. Depending on location, but plants have developed independently of it, which can benefit from a sodium intake. These plants, called halophytes, are mostly found in coastal areas or other areas where the Floor having a high concentration of sodium. Halophytes such as sugar beet, cabbage and many C4 grasses are tolerant of salt, since they can transport into the vacuoles of leaf cells, the sodium from the central cylinder out where it makes as osmotically active ion for an increase of turgor and thus instead of potassium cell elongation and the leaf area growth positively affected. Sodium thus substituted to a part of potassium, to another part, it acts but in addition to growth.

Plants that sodium can not be transported from the central cylinder out in the leaf cells, it accumulated in the xylem parenchyma. These so-called natrophoben plants include Bush beans and corn. The sodium, it came into the leaf cells, could not be transported into the vacuoles, but would remain in the cytoplasm (cytosol) and would there which is important for the formation of polymers displace potassium (sodium-induced potassium deficiency). This led Finally, inhibition of photosynthesis. The accumulation of sodium in the central cylinder of the root and the stem tissue but has a high sodium concentration negative for the plant from. By increasing the osmotic value they are obstructed in water uptake and water transport. There is a water-and nutrient supply of the sub-sheets, which leads to a reduction of the photosynthetic activity.

Since most plants contain sodium only in small amounts, many herbivores have to take additional sodium chloride from natural salt deposits.

Small amounts of sodium are stored under kerosene. For larger quantities, there are integrated handling systems with protective gas atmosphere. The sodium is often covered despite protective gas or kerosene with a layer of Na 2 O and NaOH.

Sodium fires can be personalized with metal fire powder (salt), potassium chloride, cast iron turnings, makeshift delete with sand or dry cement. Sand and cement react but to a certain extent with sodium, which reduces the quenching effect. Never apply any water, foam, dry powder, carbon dioxide or halon. These extinguishing agents highly exothermic reaction with sodium in part, which may possibly lead to stronger fires and explosions.

In compounds of the sodium is present only in the +1 oxidation state. All compounds have a strong ionic character, almost all of which are readily soluble in water. Sodium compounds are among the most important salts of many acids. Sodium salts are most often used industrially for the production of the corresponding anions, because their synthesis is cost-effective.

Sodium chloride (NaCl), often referred to as table salt or sodium chloride, is the most important and best-known sodium salt. Since it occurs in large quantities, it is the most important raw material for the production of sodium and other sodium compounds. Sodium chloride is also for the people is the most important source of sodium dar. Technically it is used among other things to preserve food and as road salt on the roads. It is named for the Sodium chloride structure, typical for many salts crystal structure.

In addition, all other possible sodium halides, ie sodium fluoride NaF, sodium bromide NaBr and sodium iodide NaI, known and stable.

There are a total of five known oxides of sodium. These are sodium oxide Na2O, sodium Na2O2, Natriumhyperoxid NaO2, Dinatriumtrioxid Na2O3 and Natriumtrioxid NaO3. Sodium oxide is included in many glass, it is formed in the glass production in the sodium carbonate used. In the combustion of sodium, it is produced only at certain temperatures (150-200 ° C, ), and stoichiometric amounts of sodium and oxygen used. This is not the case, burns sodium to sodium. This is a strong oxidizing agent and the technically most important sodium. It is used as a bleaching agent for textiles and paper, as well as a source of oxygen while diving and submarines. The other oxides are very unstable and decompose rapidly.

Sodium hydroxide (NaOH) is for the industry with the most important base. The aqueous solution of sodium hydroxide is known. It is used inter alia for the production of soap and dyes, as well as for the digestion of bauxite in the production of aluminum.

With sodium sulphide forms two salts, the sodium sulfide Na2S and sodium hydrosulfide NaHS. Both are used inter alia for heavy metal precipitation.

Na2SO4 sodium sulphate, the sodium salt of sulfuric acid, is used, inter alia, in detergents and in the paper industry in the sulfate process. Like other divalent anions sulfate forms in addition to the sodium sulfate or sodium bisulfate. Other sulfur-oxygen acids form sodium salts. An example is sodium thiosulfate Na2S2O3 used in photography as a fixer.

NaH, sodium hydride and sodium borohydride NaBH4 in the hydrogen is present in the oxidation state of-1. Both are mainly used in the organic chemistry. Sodium hydride is used as this substantially strong, low nucleophilic base for deprotonation of thiols, alcohols, amides, CH-acidic compounds, etc., sodium borohydride, however, for the reduction of ketones, for example. The latter reaction may be the presence of cerium (III) compounds selective for ketones be performed (Luche reduction). Do they come in contact with water, creates hydrogen gas H2.

Na2CO3 sodium carbonate NaHCO3 sodium hydrogen carbonate and the sodium salts of carbonic acid. They include, in addition to sodium chloride and sodium hydroxide, to the main sodium compounds. Sodium carbonate (often referred to by the trivial name soda) is needed in large quantities for the manufacture of glass. Sodium bicarbonate is used as baking soda. It forms when heated with acids carbon dioxide and water.

Sodium nitrate NaNO3, the sodium salt of nitric acid, is one of the few naturally occurring nitrate compounds (Chile saltpetre). Sodium nitrate is used as a fertilizer and as a preservative.

Organic compounds of sodium are very unstable, in contrast to those of the lithium. They are extremely reactive and can react partly with otherwise unreactive aliphatic hydrocarbons. Sufficiently stable for use in reactions are compounds containing aromatic groups, such as cyclopentadiene, which can be used as reducing agent.