Hubbry Logo
SodiumSodiumMain
Open search
Sodium
Community hub
Sodium
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Sodium
Sodium
Sodium
View on Wikipedia
from Wikipedia

Sodium, 11Na
Three large pieces of silvery metal
Sodium
Appearancesilvery white metallic
Standard atomic weight Ar°(Na)
Sodium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Li
↑
Na
↓
K
neon ← sodium → magnesium
Atomic number (Z)11
Groupgroup 1: hydrogen and alkali metals
Periodperiod 3
Block  s-block
Electron configuration[Ne] 3s1
Electrons per shell2, 8, 1
Physical properties
Phase at STPsolid
Melting point370.944 K ​(97.794 °C, ​208.029 °F)
Boiling point1156.090 K ​(882.940 °C, ​1621.292 °F)
Density (at 20° C)0.9688 g/cm3[3]
when liquid (at m.p.)0.927 g/cm3
Critical point2573 K, 35 MPa (extrapolated)
Heat of fusion2.60 kJ/mol
Heat of vaporization97.42 kJ/mol
Molar heat capacity28.230 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 554 617 697 802 946 1153
Atomic properties
Oxidation statescommon: +1
−1,[4]
ElectronegativityPauling scale: 0.93
Ionization energies
  • 1st: 495.8 kJ/mol
  • 2nd: 4562 kJ/mol
  • 3rd: 6910.3 kJ/mol
  • (more)
Atomic radiusempirical: 186 pm
Covalent radius166±9 pm
Van der Waals radius227 pm
Color lines in a spectral range
Spectral lines of sodium
Other properties
Natural occurrenceprimordial
Crystal structure ​body-centered cubic (bcc) (cI2)
Lattice constant
Body-centered cubic crystal structure for sodium
a = 428.74 pm (at 20 °C)[3]
Thermal expansion69.91×10−6/K (at 20 °C)[3]
Thermal conductivity142 W/(m⋅K)
Electrical resistivity47.7 nΩ⋅m (at 20 °C)
Magnetic orderingparamagnetic[5]
Molar magnetic susceptibility+16.0×10−6 cm3/mol (298 K)[6]
Young's modulus10 GPa
Shear modulus3.3 GPa
Bulk modulus6.3 GPa
Speed of sound thin rod3200 m/s (at 20 °C)
Mohs hardness0.5
Brinell hardness0.69 MPa
CAS Number7440-23-5
History
Namingpossibly from Arabic suda, 'headache', for soda's use as an anticephalalgic
Discovery and first isolationHumphry Davy (1807)
Symbol"Na": from New Latin natrium, coined from German Natron, 'natron'
Isotopes of sodium
Main isotopes[7] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
22Na trace 2.6019 y β+ 22Ne
23Na 100% stable
24Na trace 14.956 h β− 24Mg
 Category: Sodium
| references

Sodium is a chemical element; it has symbol Na (from Neo-Latin natrium) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been leached by the action of water from the Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans.

Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful sodium compounds, sodium hydroxide (lye) is used in soap manufacture, and sodium chloride (edible salt) is a de-icing agent and a nutrient for animals including humans.

Sodium is an essential element for all animals and some plants. Sodium ions are the major cation in the extracellular fluid (ECF) and as such are the major contributor to the ECF osmotic pressure.[8] Animal cells actively pump sodium ions out of the cells by means of the sodium–potassium pump, an enzyme complex embedded in the cell membrane, in order to maintain a roughly ten-times higher concentration of sodium ions outside the cell than inside.[9] In nerve cells, the sudden flow of sodium ions into the cell through voltage-gated sodium channels enables transmission of a nerve impulse in a process called the action potential.

Characteristics

[edit]

Physical

[edit]
Emission spectrum for sodium, showing the D line

Sodium at standard temperature and pressure is a soft silvery metal that combines with oxygen in the air, forming sodium oxides. Bulk sodium is usually stored in oil or an inert gas. Sodium metal can be easily cut with a knife. It is a good conductor of electricity and heat.

The melting (98 °C) and boiling (883 °C) points of sodium are lower than those of lithium but higher than those of the heavier alkali metals potassium, rubidium, and caesium, following periodic trends down the group.[10] These properties change dramatically at elevated pressures: at 1.5 Mbar, the color changes from silvery metallic to black; at 1.9 Mbar the material becomes transparent with a red color; and at 3 Mbar, sodium is a clear and transparent solid. All of these high-pressure allotropes are insulators and electrides.[11]

A positive flame test for sodium has a bright yellow color.

In a flame test, sodium and its compounds glow yellow[12] because the excited 3s electrons of sodium emit a photon when they fall from 3p to 3s; the wavelength of this photon corresponds to the D line at about 589.3 nm. Spin-orbit interactions involving the electron in the 3p orbital split the D line into two, at 589.0 and 589.6 nm; hyperfine structures involving both orbitals cause many more lines.[13]

Isotopes

[edit]
Main article: Isotopes of sodium

Twenty isotopes of sodium are known, but only 23Na is stable. 23Na is created in the carbon-burning process in stars by fusing two carbon atoms together; this requires temperatures above 600 megakelvins and a star of at least three solar masses.[14] Two radioactive, cosmogenic isotopes are the byproduct of cosmic ray spallation: 22Na has a half-life of 2.6 years and 24Na, a half-life of 15 hours; all other isotopes have a half-life of less than one minute.[15]

Two nuclear isomers have been discovered, the longer-lived one being 24mNa with a half-life of around 20.2 milliseconds. Acute neutron radiation, as from a nuclear criticality accident, converts some of the stable 23Na in human blood to 24Na; the neutron radiation dosage of a victim can be calculated by measuring the concentration of 24Na relative to 23Na.[16]

Chemistry

[edit]
Main article: Sodium compounds

Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. The first and second ionization energies are 495.8 kJ/mol and 4562 kJ/mol, respectively. As a result, sodium usually forms ionic compounds involving the Na+ cation.[17]

Metallic sodium

[edit]

Metallic sodium is generally less reactive than potassium and more reactive than lithium.[18] Sodium metal is highly reducing, with the standard reduction potential for the Na+/Na couple being −2.71 volts,[19] though potassium and lithium have even more negative potentials.[20]

Salts and oxides

[edit]
See also: Category:Sodium compounds
The structure of sodium chloride, showing octahedral coordination around Na+ and Cl− centres. This framework disintegrates when dissolved in water and reassembles when the water evaporates.

Sodium compounds are of immense commercial importance, being particularly central to industries producing glass, paper, soap, and textiles.[21] The most important sodium compounds are table salt (NaCl), soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH), sodium nitrate (NaNO3), di- and tri-sodium phosphates, sodium thiosulfate (Na2S2O3·5H2O), and borax (Na2B4O7·10H2O).[22] In compounds, sodium is usually ionically bonded to water and anions and is viewed as a hard Lewis acid.[23]

Two equivalent images of the chemical structure of sodium stearate, a typical soap

Most soaps are sodium salts of fatty acids. Sodium soaps have a higher melting temperature (and seem "harder") than potassium soaps.[22]

Like all the alkali metals, sodium reacts exothermically with water. The reaction produces caustic soda (sodium hydroxide) and flammable hydrogen gas. When burned in air, it forms primarily sodium peroxide with some sodium oxide.[24]

Aqueous solutions

[edit]

Sodium tends to form water-soluble compounds, such as halides, sulfates, nitrates, carboxylates and carbonates. The main aqueous species are the aquo complexes [Na(H2O)n]+, where n = 4–8; with n = 6 indicated from X-ray diffraction data and computer simulations.[25]

Direct precipitation of sodium salts from aqueous solutions is rare because sodium salts typically have a high affinity for water. An exception is sodium bismuthate (NaBiO3),[26] which is insoluble in cold water and decomposes in hot water.[27] Because of the high solubility of its compounds, sodium salts are usually isolated as solids by evaporation or by precipitation with an organic antisolvent, such as ethanol; for example, only 0.35 g/L of sodium chloride will dissolve in ethanol.[28] A crown ether such as 15-crown-5 may be used as a phase-transfer catalyst.[29]

Sodium content of samples is determined by atomic absorption spectrophotometry or by potentiometry using ion-selective electrodes.[30]

Electrides and sodides

[edit]

Like the other alkali metals, sodium dissolves in ammonia and some amines to give deeply colored solutions; evaporation of these solutions leaves a shiny film of metallic sodium. The solutions contain the coordination complex [Na(NH3)6]+, with the positive charge counterbalanced by electrons as anions; cryptands permit the isolation of these complexes as crystalline solids. Sodium forms complexes with crown ethers, cryptands and other ligands.[31]

For example, 15-crown-5 has a high affinity for sodium because the cavity size of 15-crown-5 is 1.7–2.2 Å, which is enough to fit the sodium ion (1.9 Å).[32][33] Cryptands, like crown ethers and other ionophores, also have a high affinity for the sodium ion; derivatives of the alkalide Na− are obtainable[34] by the addition of cryptands to solutions of sodium in ammonia via disproportionation.[35]

Organosodium compounds

[edit]
Main article: Organosodium chemistry
The structure of the complex of sodium (Na+, shown in yellow) and the antibiotic monensin-A

Many organosodium compounds have been prepared. Because of the high polarity of the C-Na bonds, they behave like sources of carbanions (salts with organic anions). Some well-known derivatives include sodium cyclopentadienide (NaC5H5) and trityl sodium ((C6H5)3CNa).[36] Sodium naphthalene, Na+[C10H8•]−, a strong reducing agent, forms upon mixing Na and naphthalene in ethereal solutions.[37]

Intermetallic compounds

[edit]

Sodium forms alloys with many metals, such as potassium, calcium, lead, and the group 11 and 12 elements. Sodium and potassium form KNa2 and NaK. NaK is 40–90% potassium and it is liquid at ambient temperature. It is an excellent thermal and electrical conductor. Sodium-calcium alloys are by-products of the electrolytic production of sodium from a binary salt mixture of NaCl-CaCl2 and ternary mixture NaCl–CaCl2-BaCl2. Calcium is only partially miscible with sodium, and the 1–2% of it dissolved in the sodium obtained from said mixtures can be precipitated by cooling to 120 °C and filtering.[38]

In a liquid state, sodium is completely miscible with lead. There are several methods to make sodium-lead alloys. One is to melt them together and another is to deposit sodium electrolytically on molten lead cathodes. NaPb3, NaPb, Na9Pb4, Na5Pb2, and Na15Pb4 are some of the known sodium-lead alloys. Sodium also forms alloys with gold (NaAu2) and silver (NaAg2). Group 12 metals (zinc, cadmium and mercury) are known to make alloys with sodium. NaZn13 and NaCd2 are alloys of zinc and cadmium. Sodium and mercury form NaHg, NaHg4, NaHg2, Na3Hg2, and Na3Hg.[39]

History

[edit]

Because of its importance in human health, salt has long been an important commodity. In medieval Europe, a compound of sodium with the Latin name of sodanum was used as a headache remedy. The name sodium is thought to originate from the Arabic suda, meaning headache, as the headache-alleviating properties of sodium carbonate or soda were well known in early times.[40]

Although sodium, sometimes called soda, had long been recognized in compounds, the metal itself was not isolated until 1807 by Sir Humphry Davy through the electrolysis of sodium hydroxide.[41][42] In 1809, the German physicist and chemist Ludwig Wilhelm Gilbert proposed the names Natronium for Humphry Davy's "sodium" and Kalium for Davy's "potassium".[43]

The chemical abbreviation for sodium was first published in 1814 by Jöns Jakob Berzelius in his system of atomic symbols,[44][45] and is an abbreviation of the element's Neo-Latin name natrium, which refers to the Egyptian natron,[40] a natural mineral salt mainly consisting of hydrated sodium carbonate. Natron historically had several important industrial and household uses, later eclipsed by other sodium compounds.[46]

Sodium imparts an intense yellow color to flames. As early as 1860, Kirchhoff and Bunsen noted the high sensitivity of a sodium flame test, and stated in Annalen der Physik und Chemie:[47]

In a corner of our 60 m3 room farthest away from the apparatus, we exploded 3 mg of sodium chlorate with milk sugar while observing the nonluminous flame before the slit. After a while, it glowed a bright yellow and showed a strong sodium line that disappeared only after 10 minutes. From the weight of the sodium salt and the volume of air in the room, we easily calculate that one part by weight of air could not contain more than 1/20 millionth weight of sodium.

Occurrence

[edit]

The Earth's crust contains 2.27% sodium, making it the sixth most abundant element on Earth and the fourth most abundant metal, behind aluminium, iron, calcium, and magnesium and ahead of potassium.[48]Sodium's estimated oceanic abundance is 10.8 grams per liter.[49] Because of its high reactivity, it is never found as a pure element. It is found in many minerals, some very soluble, such as halite and natron, others much less soluble, such as amphibole and zeolite. The insolubility of certain sodium minerals such as cryolite and feldspar arises from their polymeric anions, which in the case of feldspar is a polysilicate. In the universe, sodium is the 15th most abundant element with a 20,000 parts-per-billion abundance,[50] making sodium 0.002% of the total atoms in the universe.

Astronomical observations

[edit]

Atomic sodium has a very strong spectral line in the yellow-orange part of the spectrum (the same line as is used in sodium-vapor street lights). This appears as an absorption line in many types of stars, including the Sun. The line was first studied in 1814 by Joseph von Fraunhofer during his investigation of the lines in the solar spectrum, now known as the Fraunhofer lines. Fraunhofer named it the "D" line, although it is now known to actually be a group of closely spaced lines split by a fine and hyperfine structure.[51]

The strength of the D line allows its detection in many other astronomical environments. In stars, it is seen in any whose surfaces are cool enough for sodium to exist in atomic form (rather than ionized). This corresponds to stars of roughly F-type and cooler. Many other stars appear to have a sodium absorption line, but this is actually caused by gas in the foreground interstellar medium. The two can be distinguished via high-resolution spectroscopy, because interstellar lines are much narrower than those broadened by stellar rotation.[52]

Sodium has also been detected in numerous Solar System environments, including the exospheres of Mercury[53] and the Moon,[54] and numerous other bodies. Some comets have a sodium tail,[55] which was first detected in observations of Comet Hale–Bopp in 1997.[56] Sodium has even been detected in the atmospheres of some extrasolar planets via transit spectroscopy.[57]

Commercial production

[edit]

Employed in rather specialized applications, about 100,000 tonnes of metallic sodium are produced annually.[58] Metallic sodium was first produced commercially in the late nineteenth century[38] by carbothermal reduction of sodium carbonate at 1100 °C, as the first step of the Deville process for the production of aluminium:[59][60][61]

Na2CO3 + 2 C → 2 Na + 3 CO

The high demand for aluminium created the need for the production of sodium. The introduction of the Hall–Héroult process for the production of aluminium by electrolysing a molten salt bath ended the need for large quantities of sodium. A related process based on the reduction of sodium hydroxide was developed in 1886.[59]

Sodium is now produced commercially through the electrolysis of molten sodium chloride (common salt), based on a process patented in 1924.[62][63] This is done in a Downs cell in which the NaCl is mixed with calcium chloride to lower the melting point below 700 °C.[64] As calcium is less electropositive than sodium, no calcium will be deposited at the cathode.[65] This method is less expensive than the previous Castner process (the electrolysis of sodium hydroxide).[66] If sodium of high purity is required, it can be distilled once or several times.

The market for sodium is volatile due to the difficulty in its storage and shipping; it must be stored under a dry inert gas atmosphere or anhydrous mineral oil to prevent the formation of a surface layer of sodium oxide or sodium superoxide.[67]

Uses

[edit]
See also: Sodium supplements

Though metallic sodium has some important uses, the major applications for sodium use compounds; millions of tons of sodium chloride, hydroxide, and carbonate are produced annually. Sodium chloride is extensively used for anti-icing and de-icing and as a preservative; examples of the uses of sodium bicarbonate include baking, as a raising agent, and sodablasting. Along with potassium, many important medicines have sodium added to improve their bioavailability; though potassium is the better ion in most cases, sodium is chosen for its lower price and atomic weight.[68] Sodium hydride is used as a base for various reactions (such as the aldol reaction) in organic chemistry.

Metallic sodium is used mainly for the production of sodium borohydride, sodium azide, indigo, and triphenylphosphine. A once-common use was the making of tetraethyllead and titanium metal; because of the move away from TEL and new titanium production methods, the production of sodium declined after 1970.[58] Sodium is also used as an alloying metal, an anti-scaling agent,[69] and as a reducing agent for metals when other materials are ineffective.

Note the free element is not used as a scaling agent, ions in the water are exchanged for sodium ions. Sodium plasma ("vapor") lamps are often used for street lighting in cities, shedding light that ranges from yellow-orange to peach as the pressure increases.[70] By itself or with potassium, sodium is a desiccant; it gives an intense blue coloration with benzophenone when the desiccate is dry.[71]

In organic synthesis, sodium is used in various reactions such as the Birch reduction, and the sodium fusion test is conducted to qualitatively analyse compounds.[72] Sodium reacts with alcohols and gives alkoxides, and when sodium is dissolved in ammonia solution, it can be used to reduce alkynes to trans-alkenes.[73][74] Lasers emitting light at the sodium D line are used to create artificial laser guide stars that assist in the adaptive optics for land-based visible-light telescopes.[75]

Heat transfer

[edit]
Sodium–potassium alloy (NaK) phase diagram, showing the melting point of sodium as a function of potassium concentration. NaK with 77% potassium is eutectic and has the lowest melting point of the NaK alloys at −12.6 °C.[76]

Liquid sodium is used as a heat transfer fluid in sodium-cooled fast reactors[77] because it has the high thermal conductivity and low neutron absorption cross section required to achieve a high neutron flux in the reactor.[78] The high boiling point of sodium allows the reactor to operate at ambient (normal) pressure,[78] but drawbacks include its opacity, which hinders visual maintenance, and its strongly reducing properties. Sodium will explode in contact with water, although it will only burn gently in air.[79]

Radioactive sodium-24 may be produced by neutron bombardment during operation, posing a slight radiation hazard; the radioactivity stops within a few days after removal from the reactor.[80] If a reactor needs to be shut down frequently, sodium–potassium alloy (NaK) is used. Because NaK is a liquid at room temperature, the coolant does not solidify in the pipes.[81] The pyrophoricity of the NaK means extra precautions must be taken to prevent and detect leaks.[82]

Another heat transfer application of sodium is in poppet valves in high-performance internal combustion engines; the valve stems are partially filled with sodium and work as a heat pipe to cool the valves.[83]

Biological role

[edit]
Main article: Sodium in biology

Biological role in humans

[edit]

In humans, sodium is an essential mineral that regulates blood volume, blood pressure, osmotic equilibrium and pH. The minimum physiological requirement for sodium is estimated to range from about 120 milligrams per day in newborns to 500 milligrams per day over the age of 10.[84]

Diet

[edit]

Sodium chloride, also known as 'edible salt' or 'table salt'[85] (chemical formula NaCl), is the principal source of sodium (Na) in the diet and is used as seasoning and preservative in such commodities as pickled preserves and jerky. For Americans, most sodium chloride comes from processed foods.[86] Other sources of sodium are its natural occurrence in food and such food additives as monosodium glutamate (MSG), sodium nitrite, sodium saccharin, baking soda (sodium bicarbonate), and sodium benzoate.[87]

The U.S. Institute of Medicine set its tolerable upper intake level for sodium at 2.3 grams per day,[88] but the average person in the United States consumes 3.4 grams per day.[89] The American Heart Association recommends no more than 1.5 g of sodium per day.[90]

The committee to Review the Dietary Reference Intakes for Sodium and Potassium, which is part of the National Academies of Sciences, Engineering, and Medicine, has determined that there isn't enough evidence from research studies to establish Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA) values for sodium. As a result, the committee has established Adequate Intake (AI) levels instead, as follows. The sodium AI for infants of 0–6 months is established at 110 mg/day, 7–12 months: 370 mg/day; for children 1–3 years: 800 mg/day, 4–8 years: 1,000 mg/day; for adolescents: 9–13 years – 1,200 mg/day, 14–18 years 1,500 mg/day; for adults regardless of their age or sex: 1,500 mg/day.[91]

Sodium chloride (NaCl) contains approximately 39.34% of its total mass as elemental sodium (Na). This means that 1 gram of sodium chloride contains approximately 393.4 mg of elemental sodium.[92] For example, to find out how much sodium chloride contains 1500 mg of elemental sodium (the value of 1500 mg sodium is the adequate intake (AI) for an adult), we can use the proportion:

393.4 mg Na : 1000 mg NaCl = 1500 mg Na : x mg NaCl

Solving for x gives us the amount of sodium chloride that contains 1500 mg of elemental sodium

x = (1500 mg Na × 1000 mg NaCl) / 393.4 mg Na = 3812.91 mg

This mean that 3812.91 mg of sodium chloride contain 1500 mg of elemental sodium.[92]

High sodium consumption

[edit]
Main article: Health effects of salt

High sodium consumption is unhealthy, and can lead to alteration in the mechanical performance of the heart.[93] High sodium consumption is also associated with chronic kidney disease, high blood pressure, cardiovascular diseases, and stroke.[93]

High blood pressure
[edit]

There is a strong correlation between higher sodium intake and higher blood pressure.[94] Studies have found that lowering sodium intake by 2 g per day tends to lower systolic blood pressure by about two to four mm Hg.[95] It has been estimated that such a decrease in sodium intake would lead to 9–17% fewer cases of hypertension.[95]

Hypertension causes 7.6 million premature deaths worldwide each year.[96] Since edible salt contains about 39.3% sodium[97]—the rest being chlorine and trace chemicals; thus, 2.3 g sodium is about 5.9 g, or 5.3 ml, of salt—about one US teaspoon.[98][99]

One scientific review found that people with or without hypertension who excreted less than 3 grams of sodium per day in their urine (and therefore were taking in less than 3 g/d) had a higher risk of death, stroke, or heart attack than those excreting 4 to 5 grams per day.[100] Levels of 7 g per day or more in people with hypertension were associated with higher mortality and cardiovascular events, but this was not found to be true for people without hypertension.[100] The US FDA states that adults with hypertension and prehypertension should reduce daily sodium intake to 1.5 g.[99]

Physiology

[edit]

The renin–angiotensin system regulates the amount of fluid and sodium concentration in the body. Reduction of blood pressure and sodium concentration in the kidney result in the production of renin, which in turn produces aldosterone and angiotensin, which stimulates the reabsorption of sodium back into the bloodstream. When the concentration of sodium increases, the production of renin decreases, and the sodium concentration returns to normal.[101] The sodium ion (Na+) is an important electrolyte in neuron function, and in osmoregulation between cells and the extracellular fluid. This is accomplished in all animals by Na+/K+-ATPase, an active transporter pumping ions against the gradient, and sodium/potassium channels.[102] The difference in extracellular and intracellular ion concentration, maintained by the sodium-potassium pump, produce electrical signals in the form of action potentials that supports cardiac muscle contraction and promote long-distance communication between neurons.[9] Sodium is the most prevalent metallic ion in extracellular fluid.[103]

In humans, unusually low or high sodium levels in the blood is recognized in medicine as hyponatremia and hypernatremia. These conditions may be caused by genetic factors, ageing, or prolonged vomiting or diarrhea.[104]

Biological role in plants

[edit]

In C4 plants, sodium is a micronutrient that aids metabolism, specifically in regeneration of phosphoenolpyruvate and synthesis of chlorophyll.[105] In others, it substitutes for potassium in several roles, such as maintaining turgor pressure and aiding in the opening and closing of stomata.[106] Excess sodium in the soil can limit the uptake of water by decreasing the water potential, which may result in plant wilting; excess concentrations in the cytoplasm can lead to enzyme inhibition, which in turn causes necrosis and chlorosis.[107]

In response, some plants have developed mechanisms to limit sodium uptake in the roots, to store it in cell vacuoles, and restrict salt transport from roots to leaves.[108] Excess sodium may also be stored in old plant tissue, limiting the damage to new growth. Halophytes have adapted to be able to flourish in sodium rich environments.[108]

Safety and precautions

[edit]
Sodium
Hazards
GHS labelling:
GHS02: FlammableGHS05: Corrosive
Danger
H260, H314
P223, P231+P232, P280, P305+P351+P338, P370+P378, P422[109]
NFPA 704 (fire diamond)
[110]
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
1
2
W

Sodium forms flammable hydrogen and caustic sodium hydroxide on contact with water;[111] ingestion and contact with moisture on skin, eyes or mucous membranes can cause severe burns.[112][113] Sodium spontaneously explodes in the presence of water due to the formation of hydrogen (highly explosive) and sodium hydroxide (which dissolves in the water, liberating more surface). However, sodium exposed to air and ignited or reaching autoignition (reported to occur when a molten pool of sodium reaches about 290 °C, 554 °F)[114] displays a relatively mild fire.

In the case of massive (non-molten) pieces of sodium, the reaction with oxygen eventually becomes slow due to formation of a protective layer.[115] Fire extinguishers based on water accelerate sodium fires. Those based on carbon dioxide and bromochlorodifluoromethane should not be used on sodium fire.[113] Metal fires are Class D, but not all Class D extinguishers are effective when used to extinguish sodium fires. An effective extinguishing agent for sodium fires is Met-L-X.[113] Other effective agents include Lith-X, which has graphite powder and an organophosphate flame retardant, and dry sand.[116]

Sodium fires are prevented in nuclear reactors by isolating sodium from oxygen with surrounding pipes containing inert gas.[117] Pool-type sodium fires are prevented using diverse design measures called catch pan systems. They collect leaking sodium into a leak-recovery tank where it is isolated from oxygen.[117]

Liquid sodium fires are more dangerous to handle than solid sodium fires, particularly if there is insufficient experience with the safe handling of molten sodium. In a technical report for the United States Fire Administration,[112] R. J. Gordon writes (emphasis in original)

Molten sodium is extremely dangerous because it is much more reactive than a solid mass. In the liquid form, every sodium atom is free and mobile to instantaneously combine with any available oxygen atom or other oxidizer, and any gaseous by-product will be created as a rapidly expanding gas bubble within the molten mass. Even a minute amount of water can create this type of reaction. Any amount of water introduced into a pool of molten sodium is likely to cause a violent explosion inside the liquid mass, releasing the hydrogen as a rapidly expanding gas and causing the molten sodium to erupt from the container. When molten sodium is involved in a fire, the combustion occurs at the surface of the liquid. An inert gas, such as nitrogen or argon, can be used to form an inert layer over the pool of burning liquid sodium, but the gas must be applied very gently and contained over the surface. Except for soda ash, most of the powdered agents that are used to extinguish small fires in solid pieces or shallow pools will sink to the bottom of a molten mass of burning sodium – the sodium will float to the top and continue to burn. If the burning sodium is in a container, it may be feasible to extinguish the fire by placing a lid on the container to exclude oxygen.

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Sodium

View on Grokipedia
from Grokipedia
Sodium is with the atomic number and the chemical symbol Na, classified as an in group 1 of the periodic table. It is a soft, bright, silvery-white solid at that tarnishes quickly in air due to its high reactivity, and it occurs naturally only in ionic compounds such as (table salt), from which it is never found free in nature. Physically, sodium has a low of 97.8°C (370.95 K), a of 883°C (1156 K), and a density of 0.97 g/cm³, making it one of the least dense metals. Chemically, it is highly reactive, especially with water, where it undergoes a vigorous exothermic reaction to produce hydrogen gas and sodium hydroxide, and it readily forms a +1 oxidation state in compounds. Discovered in 1807 by the English chemist Humphry Davy through the electrolysis of molten sodium hydroxide, sodium is the sixth most abundant element in the Earth's crust, comprising about 2.4% by weight, and it is also prevalent in seawater at concentrations around 10,800 mg/L. Industrially, metallic sodium is produced by electrolysis of molten sodium chloride and is used as a coolant in fast-breeder nuclear reactors due to its high thermal conductivity and low neutron absorption, in the manufacture of titanium and other metals, and in sodium-vapor lamps for efficient yellow lighting. Sodium compounds, such as sodium hydroxide (lye) and sodium carbonate (soda ash), are essential in soap production, glassmaking, and water treatment. Biologically, sodium is vital for all and many , primarily as the sodium ion (Na⁺), which plays a key role in maintaining , regulating , and transmitting nerve impulses via the sodium-potassium pump. The recommended daily intake for humans is about 1,500 mg, mostly from dietary , though excessive consumption can lead to and cardiovascular issues. Only one stable , sodium-23, exists in nature, accounting for 100% of terrestrial sodium.

Physical and Chemical Properties

Physical Properties

Sodium is a with 11 and the [Ne] 3s¹. It belongs to (alkali metals) and period 3 of the periodic table. As a pure element, sodium appears as a soft, silvery-white metal that rapidly tarnishes in air to form a dull grayish layer. This softness arises from its weak , rendering it highly ductile and malleable; it can be easily cut with a knife at . Sodium exists as a under standard conditions, with no stable allotropes, though it adopts a body-centered cubic in its solid phase. Key physical constants for sodium include the following:
PropertyValueConditions
Atomic mass22.990 u-
Electronegativity0.93 (Pauling)-
Atomic radius190 pm-
First ionization energy5.14 eV-
97.8 °C-
883 °C-
Density (solid)0.968 g/cm³20 °C
Density (liquid)0.927 g/cm³At melting point
1.228 J/g·KSolid
Thermal conductivity140 W/m·K-
Electrical conductivity2.1 × 10⁷ S/m20 °C
These values highlight sodium's low melting and boiling points relative to other metals, as well as its relatively low , which allows it to float on . Its high and electrical conductivities stem from the mobility of its in the metallic lattice.

Isotopes

Sodium has a single stable , ^{23}Na, which constitutes 100% of naturally occurring sodium. This monoisotopic composition means that all terrestrial sodium is ^{23}Na, with no primordial radioactive isotopes contributing to its abundance. Twenty-one known exist, spanning mass numbers from 17 to 39. These isotopes exhibit a variety of decay modes, including beta minus (β⁻) decay, beta plus (β⁺) decay, (EC), and for the most neutron-deficient ones, with half-lives ranging from microseconds to years. The only stable isotope is ^{23}Na, while all others are radioactive and artificially produced. Among the radioactive isotopes, ^{24}Na and ^{22}Na are the most significant due to their relatively long half-lives and practical applications. ^{24}Na undergoes β⁻ decay with a half-life of 14.96 hours, emitting gamma rays that facilitate detection. Similarly, ^{22}Na decays primarily via β⁺ emission and EC, with a half-life of 2.602 years, producing positrons suitable for imaging. Radioactive sodium isotopes are produced artificially, most commonly through in nuclear reactors. The primary reaction for ^{24}Na is the on ^{23}Na: ^{23}Na + n → ^{24}Na, with a thermal neutron capture cross-section of 0.53 barns. This process typically involves irradiating sodium metal or compounds like Na₂CO₃ in a high-flux reactor (∼5 × 10^{13} n/cm²/s) for 8–24 hours, yielding activities exceeding 30 GBq/g at the end of . ^{22}Na can be produced via high-energy reactions such as ^{23}Na(n,2n)^{22}Na or through on isotopes followed by β⁻ decay. These isotopes find applications in and scientific research. ^{24}Na serves as a tracer in to study and in medical diagnostics to monitor distribution and blood flow. ^{22}Na is used in (PET) for calibration and imaging studies, leveraging its positron emission. Key nuclear properties include the binding energy per for the stable ^{23}Na, which is 8.111 MeV, reflecting its nuclear stability. The neutron capture cross-section of ^{23}Na (0.53 barns) underscores its utility in reactor-based isotope production.

Chemical Reactivity

Metallic Sodium

Metallic sodium is a soft, silvery-white characterized by its low density and high reactivity. It exhibits low hardness, rated at 0.5 on the , allowing it to be easily cut with a , and demonstrates high , enabling it to be drawn into wires or shaped without fracturing. Sodium metal has a relatively low of 97.8 °C, which facilitates its handling in settings but requires careful temperature control to maintain solidity. To obtain pure metallic sodium for laboratory use, it is typically purified by , which removes non-volatile impurities such as calcium, carbon, and oxygen that arise from electrolytic production processes. This method involves heating the sodium under reduced pressure, allowing the metal to vaporize and condense away from contaminants, yielding high-purity samples essential for sensitive applications. Due to its extreme reactivity with atmospheric oxygen and moisture, metallic sodium must be stored under an inert liquid such as mineral oil or kerosene to form a protective barrier preventing oxidation and spontaneous ignition. Exposure to air leads to rapid surface tarnishing, while contact with water triggers a violent reaction. The reaction of sodium with water is highly exothermic and produces hydrogen gas, sodium hydroxide, and significant heat: 2Na (s)+2H2O (l)→2NaOH (aq)+H2(g)ΔH≈−183 kJ/mol (per mole of Na)\begin{align*} &2\text{Na (s)} + 2\text{H}_2\text{O (l)} \rightarrow 2\text{NaOH (aq)} + \text{H}_2\text{(g)} \\ &\Delta H \approx -183 \, \text{kJ/mol (per mole of Na)} \end{align*} This vigorous displacement reaction generates flammable hydrogen and sufficient heat to ignite the gas, posing hazards in handling. When heated in a , metallic sodium or its vapors emit a characteristic bright yellow-orange color, arising from the sodium D-lines, a doublet of emission lines at approximately 589.0 nm and 589.6 nm in the . This is widely used in tests for qualitative identification of sodium in . In laboratory synthesis, metallic sodium serves as a powerful , particularly in such as the , where it dissolves in liquid to partially reduce aromatic rings to 1,4-cyclohexadienes. This application highlights its utility in constructing complex carbon frameworks, though it requires stringent conditions to avoid side reactions.

Compounds and Reactions

Sodium forms a variety of compounds, predominantly ionic in nature due to its low first of 496 kJ/mol, which facilitates the loss of its to achieve a stable Na⁺ cation. This ionic character is evident in most sodium salts, where the Na⁺ ion interacts electrostatically with anions in lattice structures. The standard for the Na⁺/Na couple is -2.71 V, indicating sodium's strong reducing power and tendency to form positive ions in reactions. Among sodium's oxides, (Na₂O) is a basic compound produced by the controlled burning of sodium metal in limited oxygen, following the reaction 4Na + O₂ → 2Na₂O. Na₂O adopts an antifluorite and reacts vigorously with water to form , underscoring its basic properties. In contrast, (Na₂O₂), formed when sodium burns in excess oxygen, is a pale yellow solid with strong oxidizing capabilities due to the O₂²⁻ . Na₂O₂ decomposes upon heating above 300°C and is used in applications requiring oxygen release, such as bleaching agents. Sodium halides, including NaF, NaCl, NaBr, and NaI, are typically synthesized by direct combination of sodium metal with the corresponding gas, such as 2Na + Cl₂ → 2NaCl. These compounds exhibit , with NaCl featuring a face-centered cubic rock salt lattice where Na⁺ and Cl⁻ ions alternate. trends among sodium halides increase from NaF to NaI, influenced by decreasing lattice energies as the anion size grows, though NaF remains relatively insoluble compared to the others. NaCl, the most abundant, serves as a prototypical ionic solid with high and electrical conductivity in molten form. Other important sodium salts include (NaOH), a strong base produced industrially via the of aqueous NaCl solution in the chlor-alkali process, where Na⁺ ions migrate to the to form NaOH. NaOH dissociates completely in solution to yield OH⁻ ions, enabling its use in adjustment and . (Na₂CO₃), commonly known as soda ash, is an anhydrous white powder obtained from natural ore or synthetic processes like the Solvay method, acting as a mild base in detergents and glass production. Sodium participates in single displacement reactions, exemplified by its reaction with : 2Na + 2HCl → 2NaCl + H₂, where sodium displaces from the acid due to its higher reactivity. This process highlights sodium's role as a , liberating dihydrogen gas vigorously. Such reactions underscore the element's position in the , above . Organosodium compounds, such as alkyl derivatives analogous to , are less stable than their counterparts and often exist as insoluble polymeric solids, limiting their synthetic utility compared to organolithiums.

Solutions and Phases

In aqueous solutions, the sodium cation (Na⁺) is strongly hydrated, forming a primary with a of approximately 6 molecules arranged in an octahedral . The effective of Na⁺ is 0.95 Å, which influences its and mobility compared to larger alkali ions. Solutions of sodium salts derived from strong acids and bases, such as NaCl, exhibit neutrality near 7 due to the lack of by either . Sodium hydroxide (NaOH) solutions are highly caustic, with corrosivity increasing with concentration due to enhanced activity and exothermic dilution effects. At concentrations above 40 wt%, dilution generates sufficient to potentially the solution, posing risks of formation and severe burns. Lower concentrations (e.g., 10-20 wt%) still exhibit strong alkaline properties, facilitating applications in adjustment and , but require careful handling to mitigate skin and eye damage. Exotic phases of sodium include electrides, where electrons serve as anions, as in complexes like [Na⁺(cryptand)][e⁻], stabilized by macrocyclic ligands such as 2.2.2-cryptand that encapsulate the cation. These compounds display a characteristic deep blue color attributable to the trapped , similar to solutions, but they are thermally and chemically unstable, decomposing rapidly in air or moisture. Sodides feature sodium anions (Na⁻) in ionic structures, often co-solvated with countercations like Li⁺ in solvents, forming clusters with intermetallic-like bonding characteristics due to the expanded of Na⁻. structures of sodides, such as those with hexacyclen ligands, reveal close cation-anion contacts and high reactivity, limiting their isolation to inert atmospheres. Liquid sodium, above its melting point of 97.8°C, exhibits low , decreasing from approximately 0.68 cP at 100°C to 0.23 cP at 550°C, which facilitates its use as a . is similarly temperature-dependent, valued at around 200 dyn/cm near the melting point and dropping to about 100 dyn/cm at higher temperatures, influencing behavior in non-aqueous systems like reactor coolants. Phase diagrams of sodium-potassium (NaK) alloys reveal eutectic compositions with low melting points, such as the 22 mol% Na-78 mol% K mixture at -12.6°C, enabling room-temperature states for applications in cooling and batteries. These alloys maintain over wide temperature ranges due to minimal solid solubility and a deep eutectic trough, enhancing thermal stability in non-aqueous environments.

History and Discovery

Early Observations

One of the earliest recognized sodium compounds was , a naturally occurring mineral primarily composed of decahydrate (Na₂CO₃·10H₂O) and about 17% , sourced from evaporated lake beds in . Dating back to around 3000 BCE, natron played a crucial role in Egyptian mummification processes, where it was applied to desiccate bodies by absorbing moisture and preventing decay, as evidenced by archaeological remains and historical accounts of practices. This use extended beyond preservation to purification rituals, highlighting natron's practical significance in ancient society. In medieval , sodium compounds were known as "soda," derived from the term "suwid" or "suwwad," referring to extracts from the ash of plants ( species) burned to produce alkaline substances. These plant ashes, rich in , were employed in alchemical experiments for their fluxing properties and in early chemical processes, marking a transition from empirical uses to more systematic study in following the translation of texts during the . By the 18th century, chemists began distinguishing sodium-based compounds from similar potassium ones. In 1759, Andreas Sigismund Marggraf conducted detailed analyses, preparing pure samples of sodium nitrate and potassium nitrate and demonstrating their chemical differences through distinct flame colors when mixed with gunpowder, laying groundwork for elemental identification. The term "natrium," adopted for the element in the early 19th century, stems from the Arabic "natrun," an ancient name for natron, which influenced the modern chemical symbol Na. Sodium compounds also held cultural importance in glassmaking, particularly in the production of soda-lime glass since Roman times, where served as the primary to lower melting temperatures of silica sands, enabling widespread use in vessels, windows, and decorative items across the empire. This application, reliant on Egyptian imports, underscores the compound's role in technological and artistic advancements.

Isolation and Development

The isolation of elemental sodium was achieved in 1807 by British chemist , who used to decompose molten (NaOH). Davy employed a battery consisting of over 200 voltaic cells to pass a strong through the dry, fused caustic soda, resulting in the deposition of small globules of silvery sodium metal at the while oxygen was liberated at the . He publicly announced the discovery in a lecture to the Royal Society on November 19, 1807, and formally published it in 1808, deriving the name "sodium" from "soda," the traditional term for sodium compounds like . Following Davy's electrolytic isolation, early efforts to produce sodium chemically focused on thermal reduction techniques. Attempts to heat with carbon at elevated temperatures failed to yield the pure metal, instead forming sodium carbide (Na₂C₂) as the primary product due to the strong affinity of sodium for carbon under those conditions. Alternative chemical reductions, such as using metal to displace sodium from its compounds, allowed small-scale preparation but were impractical for larger quantities owing to 's scarcity and high reactivity. Commercial viability emerged in 1855 with the Deville process, developed by French chemist Henri Étienne Sainte-Claire Deville, which reduced (Na₂CO₃) with carbon in the presence of at approximately 1100 °C. The iron acted as a catalyst to facilitate sodium vapor formation while minimizing carbide side products, enabling the production of several tons annually to support growing demand for aluminum synthesis. This marked the first industrial-scale sodium production, though it was energy-intensive and produced significant waste. In the 1890s, American chemist Hamilton Young Castner introduced an improved electrolytic method, electrolyzing molten at about 330 °C using an cathode and anode. This operated at a lower temperature than Davy's original setup, reducing energy consumption and corrosion issues, and achieved efficiencies of around 80-90%, dominating production until the mid-20th century. The transition to even more efficient methods occurred in the with the , invented by American engineer J. Cloyd Downs and patented in 1924. This design electrolyzes a molten of (NaCl) and (CaCl₂) to lower the melting point to 600 °C, yielding sodium metal at the and gas (Cl₂) at the as a commercially valuable byproduct, thereby enhancing overall process .

Natural Occurrence

Terrestrial Sources

Sodium has a relatively high cosmic abundance, with a mass fraction of approximately 0.003% in the , ranking around the 11th most abundant element. On , sodium constitutes about 2.36% of the crust by weight, making it the sixth most abundant element there and primarily occurring in such as feldspars. For instance, (NaAlSi₃O₈), a key component of feldspars, is a major sodium-bearing mineral in igneous and metamorphic rocks, contributing significantly to the element's crustal distribution. In the oceans, sodium is the dominant cation, comprising 1.08% of as Na⁺ ions at an average concentration of 10.8 g/L. This equates to roughly 30.6% of the total dissolved salts in , predominantly in the form of (NaCl), which accounts for about 85% of the ionic content. 's sodium content arises from the of continental rocks and volcanic inputs, maintaining a stable concentration through global hydrological cycles. Sodium also occurs in various minerals on land, including evaporite deposits like (NaCl), which forms vast salt beds from ancient evaporated seas. Other important sources include (Na₂CO₃·NaHCO₃·2H₂O), a mineral found in alkaline lake deposits, and (Na₃AlF₆), a mineral historically significant for aluminum production. In soil and water cycles, sodium is mobilized through brines—concentrated saline solutions in arid regions and —and evaporites, facilitating its transport and deposition in sedimentary environments.

Extraterrestrial Distribution

Sodium is primarily synthesized in through the cycle during burning and via reactions in the phase of massive , where alpha capture on isotopes contributes significantly to its production. In the , which occurs in the cores of with masses greater than about 8 solar masses after carbon exhaustion, the reaction 20Ne(α,p)23Na^{20}\mathrm{Ne}(\alpha, p)^{23}\mathrm{Na} produces the dominant 23Na^{23}\mathrm{Na}. This process builds up sodium alongside magnesium and other intermediates in the oxygen-neon-magnesium core, contributing to the element's galactic abundance before being dispersed through or supernovae. In the solar system, sodium's abundance is evident in the Sun's spectrum, where it produces prominent absorption lines known as the sodium D-lines at 589.0 nm and 589.6 nm in the of the . These arise from neutral sodium atoms in the and are among the strongest features, reflecting the element's relatively high cosmic abundance. The solar sodium abundance is estimated at log⁡ϵ(Na)=6.17±0.02\log \epsilon (\mathrm{Na}) = 6.17 \pm 0.02 (where log⁡ϵ=log⁡10(NNa/NH)+12\log \epsilon = \log_{10} (N_{\mathrm{Na}}/N_{\mathrm{H}}) + 12), derived from non-local (NLTE) analyses of high-resolution spectra, indicating sodium constitutes about 1.5 parts per million by number relative to . Earlier determinations placed it around 6.33, but refined 3D atmospheric models have lowered this value slightly while confirming the D-lines' diagnostic power. Meteorites provide direct evidence of sodium's distribution in primitive solar system materials, with carbonaceous chondrites—considered representatives of the solar system's building blocks—containing approximately 0.5–0.6 wt% sodium, primarily bound in silicates like and pyroxenes. This abundance mirrors the solar value when adjusted for volatility, as sodium condensed early in the solar nebula despite its moderate volatility. Lunar , analyzed from Apollo samples and , shows sodium abundances averaging 0.23 wt%, significantly depleted compared to the continental crust of (around 2.4 wt%) due to the Moon's formation processes, which preferentially lost volatile elements like sodium. Sodium in lunar is hosted in minerals such as and other , with variations linked to mare vs. highland compositions. On planetary scales, sodium is detected in the atmospheres and s of several bodies. In Jupiter's atmosphere, neutral sodium atoms originate from volcanic eruptions on its moon Io, where (NaCl) is emitted and dissociated, forming a vast sodium nebula that extends into Jupiter's and contributes to auroral emissions. Observations show this sodium cloud varies with Io's volcanic activity, influencing Jupiter's radio emissions through plasma interactions. Similarly, Mercury's tenuous features prominent sodium emissions at the D-lines, sourced from micrometeorite impacts, sputtering, and thermal desorption from the surface , which contains about 2–4 wt% sodium in . Ground-based and observations reveal seasonal variations in brightness due to Mercury's eccentric and solar , with peak emissions reaching column densities of 101110^{11} atoms/cm². Interstellar sodium is traced through absorption in atomic gas clouds via the prominent Na I D-lines in and optical spectra of background stars, revealing its presence in the diffuse (ISM) with typical column densities of 101110^{11}–101310^{13} atoms/cm². These observations map neutral sodium as a kinematic tracer of ISM structure, showing correlations with dust and molecular clouds, though radio detections are limited to molecular species like NaH rather than atomic lines. In comets, sodium appears in extended tails, as observed in Hale-Bopp (C/1995 O1), where a distinct neutral sodium tail—separate from dust and tails—spanned millions of kilometers and glowed via resonance scattering of sunlight. This tail, detected in 1997, arose from sodium release from dust grains or subsurface ices, with production rates up to 10²⁶ atoms/s, highlighting comets as reservoirs of volatile sodium. Recent missions in the 2020s, such as NASA's Parker Solar Probe, have advanced understanding of sodium in the heliosphere by directly sampling the solar corona and wind, where heavy ions including sodium (as Na⁺) constitute trace components of the outflow. Launched in 2018, the probe's in-situ measurements during close approaches (as near as 8.5 solar radii) detect sodium flux in the slow solar wind, linking it to coronal composition and heating processes, with abundances consistent with photospheric values scaled by first ionization potential effects. These observations confirm sodium's role in solar wind dynamics, including wave-particle interactions that accelerate the plasma.

Production

Extraction Methods

Sodium metal is primarily extracted through of molten , a process that leverages electrochemical reduction to isolate the metal from its ionic form. At the , sodium ions are reduced according to the Na⁺ + e⁻ → Na, producing molten sodium due to its low of 97.8°C. Simultaneously, at the , ions are oxidized via 2Cl⁻ → Cl₂ + 2e⁻, yielding gas as a valuable . This electrolytic decomposition requires the to be molten, as solid does not conduct effectively, and the process operates at elevated temperatures to maintain liquidity while minimizing energy loss. The represents the standard industrial apparatus for this , featuring a cylindrical vessel lined with material to withstand high temperatures. The consists of a of (NaCl) and (CaCl₂) in a typical ratio that lowers the from 801°C for pure NaCl to approximately 600°C, facilitating operation at 590–610°C. A central is surrounded by a concentric iron , with a cylinder separating the products to prevent recombination of sodium and ; molten sodium rises to the cathode surface and is tapped off, while gas is collected above the . , the primary raw material, is sourced from terrestrial deposits or evaporated . An alternative electrolytic variant, the , involves the of molten (NaOH) at around 330°C using an cathode and or anode, producing sodium metal at the cathode alongside and oxygen gases. This method avoids chloride-based electrolytes but requires careful control to manage the more corrosive environment. Historically, prior to widespread electrolysis, sodium was produced via the Deville process, which reduced (Na₂CO₃) with carbon at approximately 1100°C, but this thermal method was inefficient due to high energy demands and significant side reactions forming and other impurities. Purity in electrolytically produced sodium is challenged by calcium impurities introduced from the CaCl₂ additive in the , which can form calcium-sodium alloys; these are removed through under vacuum, exploiting the higher of calcium (1484°C) compared to sodium (883°C). Current efficiencies in the Downs typically range from 80% to 90%, reflecting losses from back-reactions and side products, while overall yields approach 90% with optimized conditions. The demands significant electrical energy, approximately 9.8–10.5 kWh per kilogram of sodium, accounting for overpotentials, ohmic losses, and the need to maintain molten conditions.

Industrial Scale

Global production of sodium metal reached approximately 71,000 metric tons in , with estimates for the early 2020s averaging around 70,000 to 100,000 metric tons annually, predominantly sourced from , which accounts for over 80% of output, followed by facilities in the and including . As of 2023, accounted for over 90% of global production, with growing demand from sodium-ion batteries expected to drive expansion. Major producers are predominantly Chinese firms such as Lanta Industrial Co., Ltd. and Wanji Holdings Group, with limited production outside , including by MSSA S.A.S. in . The economic aspects of sodium manufacturing are heavily influenced by cost factors, where electricity constitutes about 50% of production expenses due to the energy-intensive electrolysis of molten sodium chloride, requiring roughly 10-12 kWh per kilogram of sodium produced. Raw materials, primarily sodium chloride sourced from underground mines or evaporated seawater, represent another significant portion, with global salt availability ensuring low input costs but transportation adding variability. Market trends indicate a historically stable but slowly declining demand for traditional uses like and dyes due to the rise of alternative reagents, yet projections for 2025 suggest slight growth to around 75,000-85,000 metric tons, driven by increasing interest in sodium for advanced batteries amid lithium supply constraints. Environmental considerations in industrial-scale production center on managing the chlorine gas byproduct from , which is typically captured and sold for use in or chemicals, mitigating release risks, while the process's high —primarily from fossil fuel-based in major producing regions—contributes to significant carbon emissions, prompting efforts toward integration in facilities.

Applications

Industrial and Chemical Uses

Sodium metal serves as a vital reducing agent in various chemical syntheses due to its high reactivity. In the production of titanium, sodium is employed in the Hunter process, where titanium tetrachloride (TiCl₄) is reduced to metallic titanium. This process, developed in the early 20th century, utilizes molten sodium to provide the necessary electrons for reduction, producing titanium sponge that is further processed into ingots. Additionally, sodium acts as a reducing agent in the synthesis of certain dyes and pharmaceuticals, where it facilitates the formation of organic intermediates by displacing less reactive metals or halogens. In alloying applications, sodium is incorporated into specific metal mixtures to enhance properties such as fluidity and low-temperature performance. The sodium- alloy (NaK), composed of approximately 22% sodium and 78% by weight, has a eutectic of -12.6°C, allowing it to remain near . This alloy is valued in industrial settings for its use in specialized coolants and systems. In aluminum alloys, particularly Al-Si alloys, sodium additions of 1-5 wt% in master alloys promote grain refinement of the eutectic structure, improving mechanical properties like and reducing during solidification. Sodium compounds play essential roles in everyday industrial materials. Sodium carbonate (Na₂CO₃), also known as soda ash, is a key flux in the production of soda-lime glass, where it lowers the melting temperature of silica (SiO₂) and facilitates the incorporation of lime (CaO) to form a durable, transparent material used in windows, bottles, and containers. Sodium hydroxide (NaOH), or caustic soda, is central to the process in manufacturing, reacting with fats or oils to produce and sodium salts of fatty acids, yielding solid soaps with cleansing properties. In , (NaOCl) is produced industrially by reacting gas with solutions, resulting in a stable solution used for disinfection and oxidation in municipal and industrial processes. This compound effectively eliminates pathogens and organic contaminants, supporting and environmental compliance. Globally, the consumption of metallic sodium for chemical and industrial applications was projected to surpass 127,400 metric tons by 2024, reflecting growing demand in these sectors as of 2021.

Energy and Heat Transfer

Liquid sodium serves as an effective coolant in fast breeder reactors due to its favorable thermal properties and low neutron absorption cross-section, which minimizes moderation of fast neutrons essential for breeding fuel. Notable examples include the French Phenix reactor, operational from 1973 to 2009, and the Superphénix reactor, which ran from 1986 to 1997 and was the world's largest sodium-cooled fast reactor with a thermal power of 3,000 MWt (1,242 MWe). These reactors utilized liquid sodium to achieve high power densities while maintaining efficient heat removal without significant neutron slowing. The thermal conductivity of liquid sodium, approximately 80-85 W/m·K at operating temperatures, enables effective in reactor cores, supporting outlet temperatures of 500-550°C and overall system operations between 400-600°C. This high of 883°C allows low-pressure operation, reducing structural stresses compared to water-cooled systems, while its compatibility with austenitic stainless steels limits under controlled oxygen and impurity levels. In fast breeder designs, these properties facilitate breeding ratios exceeding 1.0, enhancing . Sodium-sulfur batteries employ molten sodium as the (negative electrode), liquid sulfur as the , and β-alumina solid to enable sodium-ion transport at temperatures around 300°C. This configuration yields a practical of about 150 Wh/kg, with cycle life up to 4,500 cycles in commercial units, making them suitable for grid-scale . The 's high ionic conductivity, over 0.2 S/cm at operating temperature, ensures efficient charge-discharge performance. In systems, sodium vapor functions as the working fluid in high-temperature pipes, transferring from receivers to storage or power generation components at temperatures up to 800°C. Loop-type sodium pipes, often integrated into or dish-Stirling collectors, demonstrate thermal transport capacities exceeding 10 kW per pipe with minimal drops. These systems leverage sodium's low and high of for efficient isothermal . Historically, sodium-cooled reactors faced challenges in early applications, such as the submarine's S2G reactor in the 1950s, where leaks in superheaters and generators due to and stresses led to operational downtime and eventual redesign to a pressurized by 1959. These incidents highlighted the need for advanced impurity control and in sodium systems.

Emerging Technologies

Sodium-ion batteries represent a prominent emerging leveraging sodium's abundance and low cost for electrochemical , particularly as an alternative to lithium-ion systems for electric and grid applications. These batteries typically employ layered cathodes, such as NaFeO₂, which provide stable sodium intercalation and high capacity due to their structural similarity to lithium counterparts, enabling reversible ion movement during charge-discharge cycles. Hard carbon serves as the material, offering suitable sodium storage through a disordered structure that accommodates larger ions without significant volume expansion. First-generation cells achieve densities around 160 Wh/kg, sufficient for stationary storage and entry-level EVs, while exhibiting 25-30% lower production costs than lithium-ion batteries owing to inexpensive raw materials like iron and carbon. Commercialization efforts have accelerated, with companies like scaling production for EV applications in 2025, including expanded facilities to meet demand for low-cost packs. Faradion has piloted pouch cells targeting 160 Wh/kg for integration into vehicles, while HiNa Battery unveiled prototype cells in 2025, partnering with Chinese automakers for testing in prototypes that demonstrate viability for mass-market adoption. Ongoing research focuses on all-solid-state sodium batteries, which replace liquid electrolytes with non-flammable solid conductors to enhance safety and eliminate leakage risks, achieving cycle lives exceeding 1000 cycles with minimal capacity fade. analogs, such as iron hexacyanoferrate derivatives, are being optimized as cathodes for these systems, offering open frameworks for fast sodium diffusion and high stability over thousands of cycles. Beyond batteries, sodium compounds enable innovations in , where sodium alanate (NaAlH₄) serves as a lightweight capable of releasing up to 5.6 wt% under moderate conditions, with recent catalyst enhancements improving kinetics for reversible uptake in applications. In desalination, sodium-selective membranes, such as those based on ceramics, facilitate targeted ion recovery from , allowing efficient extraction of Na⁺ while minimizing energy use in processes for sustainable . Market projections indicate sodium-ion battery production could reach 10 GWh annually by 2025 in alone, scaling to over 50 GWh globally by 2030, driven by demand for affordable EV and grid storage solutions.

Biological and Environmental Role

Role in Human Physiology

Sodium is an essential in human physiology, serving as the primary cation in and playing a critical role in maintaining and throughout the body. It helps regulate the volume of by influencing water movement across cell membranes, ensuring proper hydration and cellular function. Additionally, sodium is vital for the transmission of impulses and muscle contractions, where it contributes to the generation and propagation of action potentials in neurons and muscle cells. The sodium-potassium ATPase pump, a key , actively transports three sodium ions out of the cell and two ions into the cell per molecule of ATP hydrolyzed, establishing and maintaining the necessary for these processes. Recommended daily intake of sodium for adults varies by guideline, with the U.S. Dietary Guidelines suggesting 1,500 to 2,300 mg, the American Heart Association recommending no more than 2,300 mg per day (ideally ≤1,500 mg for most adults), and the World Health Organization advising less than 2,000 mg per day, to support these physiological functions without excess risk. A major dietary source is table salt (, NaCl), which contains approximately 40% sodium by weight, with about 2.3 grams of sodium per . In , sodium ions are crucial for the depolarization phase of action potentials, where voltage-gated sodium channels open in response to membrane depolarization, allowing rapid influx of Na⁺ and propagating the electrical signal along axons. Furthermore, sodium balance is regulated by hormones such as aldosterone, which promotes sodium reabsorption in the kidneys' distal tubules and collecting ducts, thereby conserving fluid and stabilizing and pressure. Chronic low sodium intake may activate the renin-angiotensin-aldosterone system, potentially leading to elevated lipids and increased mortality risk according to some studies. Deficiency of sodium, known as hyponatremia, occurs when serum sodium levels fall below 135 mmol/L and can disrupt nerve function and fluid balance, leading to symptoms such as confusion, nausea, seizures, and in severe cases, coma. This condition often arises from excessive water intake relative to sodium or losses through sweating, vomiting, or diuretic use, impairing the Na⁺/K⁺ ATPase pump's ability to maintain membrane potentials. Excess sodium intake, conversely, is associated with increased blood pressure and hypertension risk through mechanisms involving fluid retention and vascular effects, though detailed health impacts are addressed elsewhere.

Role in Plant and Animal Biology

In plants, sodium is generally considered non-essential for growth and development, as most species can complete their life cycles without it. However, in certain halophytes such as saltbush (Atriplex spp.), sodium can partially substitute for potassium in functions like maintaining cell turgor and enzyme activation, particularly under potassium-limited conditions. This substitution is more pronounced in saline environments, where sodium aids osmotic regulation by accumulating in vacuoles to balance water uptake from high-salinity soils, thereby sustaining turgor pressure without excessive energy expenditure on organic osmolytes. Despite these benefits, sodium becomes toxic at concentrations exceeding 50 mM in the soil solution, leading to ionic imbalances that disrupt nutrient uptake, cause oxidative stress, and inhibit photosynthesis in non-tolerant species. Mechanisms of sodium tolerance in , such as those in halophytes, involve the Salt Overly Sensitive () pathway, a key signaling cascade that regulates sodium extrusion and compartmentalization to prevent cytoplasmic accumulation. The pathway, comprising proteins like SOS1 (a plasma membrane Na⁺/H⁺ ), SOS2 (a ), and SOS3 (a calcium sensor), activates under salt stress to maintain ion homeostasis, with post-2010 research highlighting its role in natural variation of tolerance across crops like and . In animals, sodium plays a vital role in , particularly in marine species that must counteract the high of their environment to prevent . For instance, fish in actively excrete excess sodium through specialized chloride cells in their gills, which use Na⁺/K⁺-ATPase pumps to maintain internal balance and osmotic equilibrium. This process is less critical in terrestrial or freshwater animals compared to humans, where sodium's primary functions center on volume regulation rather than constant ion extrusion against hypertonic media. Regarding human nutrition, dietary sodium primarily originates from processed and prepared foods, which account for approximately 70-75% of intake in many high-income countries, while naturally occurring sodium in unprocessed foods contributes about 10-15%. In the United States, the average daily sodium consumption among adults is around 3.4 g, far exceeding the World Health Organization's recommended level of less than 2 g per day. In March 2025, WHO released guidelines endorsing the use of lower-sodium salt substitutes, such as potassium-enriched variants, as an effective strategy for reducing population sodium intake and lowering blood pressure, aiming to curb non-communicable diseases through population-wide reductions. Excessive sodium intake is linked to and elevated cardiovascular risks, with each additional gram per day associated with a 2-8% increase in , depending on individual sensitivity and baseline levels. The Dietary Approaches to Stop (, which emphasizes fruits, , and low-fat while limiting sodium to about 1.6 g daily in its lower-sodium variant, has been shown to reduce systolic by 5-6 mmHg in hypertensive individuals, thereby lowering the incidence of cardiovascular events.

Environmental Impact

Sodium extraction through and processing contributes to significant , particularly loss and increased in surrounding ecosystems. In regions like the , excessive water diversion for salt harvesting and related industrial activities has led to a shrinkage of over 70% of the lake's volume since the 1980s, resulting in the exposure of beds that release toxic dust laden with and salts, affecting air quality and habitats. This process also involves discharge, which elevates levels in nearby freshwater systems, stressing aquatic life and altering microbial communities. For instance, salt harvesting from hypersaline lakes can cause localized increases and of infrastructure, further compounding ecological stress through soil salinization. Industrial releases of sodium compounds, such as (NaOH) from chlor-alkali production, pose risks to by altering in wastewater effluents. When discharged without adequate treatment, NaOH raises the alkalinity of receiving waters, potentially harming and populations by disrupting and enzyme functions in sensitive species. Similarly, , used as a non-selective , can enter waterways via agricultural runoff; although it exhibits low bioaccumulation potential due to high and lack of adsorption to particulates, it contributes to in aquatic organisms and soil dispersion upon breakdown, indirectly affecting stability. In the atmosphere, sodium from aerosols serves as a major natural source, influencing formation and patterns. These aerosols, primarily composed of particles emitted from ocean waves, act as , enhancing cloud reflectivity and potentially cooling regional climates by scattering sunlight. However, anthropogenic enhancements, such as increased emissions from coastal activities, can amplify these effects, altering rainfall distribution and contributing to when interacting with pollutants. Sodium plays a conservative role in global oceanic cycling, maintaining relatively constant concentrations relative to due to minimal biological uptake and steady inputs from rivers and hydrothermal vents. This stability contrasts with terrestrial disruptions, where road salt (NaCl) application for de-icing leads to runoff that elevates sodium and levels in freshwater systems, causing salinization that disrupts aquatic food webs and promotes proliferation. While not a direct driver of , this increased exacerbates nutrient imbalances in lakes and streams, reducing and impairing processes. Mitigation efforts in the 2020s include regulatory frameworks under the European Union's , which set guidelines for managing in surface waters to protect aquatic ecosystems, though specific limits on de-icing salts remain inconsistent across member states. Emerging research highlights potential interactions between sodium ions and in marine environments, where salts may influence particle aggregation and transport through food webs, underscoring gaps in current controls.

Safety and Handling

Health Hazards

Exposure to metallic sodium poses significant acute health risks due to its highly reactive nature. When metallic sodium contacts moist skin or eyes, it rapidly reacts with to produce (NaOH), a strong that causes severe chemical burns through liquefaction and protein denaturation. These burns can penetrate deeply into tissues, leading to pain, blistering, ulceration, and potential permanent scarring or vision loss if the eyes are affected. Inhalation of sodium vapors or fumes from heated metal can irritate the and, in severe cases, result in noncardiogenic , characterized by fluid accumulation in the lungs and symptoms such as coughing, , and respiratory distress. Chronic exposure in industrial settings primarily involves sodium hydroxide, which is corrosive to skin and eyes, often resulting in irritant contact dermatitis with symptoms including redness, dryness, cracking, and chronic inflammation upon repeated contact. Prolonged inhalation of NaOH dusts or mists can cause ulceration of the nasal passages and upper respiratory tract irritation. Sodium azide, another sodium compound used in laboratories and industry, exhibits toxicity akin to cyanide by inhibiting cytochrome C oxidase in mitochondria, leading to cellular hypoxia, metabolic acidosis, and potentially fatal cardiovascular and neurological effects. Toxicity metrics for elemental sodium metal are not typically expressed as LD50 values due to its reactivity preventing standard or dermal absorption tests, though analogous sodium compounds like have an oral LD50 of approximately 6.4 mg/kg in rats, highlighting severe systemic risks. The (OSHA) sets a (PEL) for at 2 mg/m³ as a time-weighted average over an 8-hour shift to prevent irritation and corrosive effects. Medical incidents involving sodium often occur in laboratory settings, such as fires where molten sodium ignites, causing explosive reactions and burns; these fires have been documented to require smothering with dry sand to avoid exacerbating the reaction with water. Asthmatics represent a vulnerable group, as inhalation of sodium chloride aerosols can provoke bronchoconstriction and exacerbate airway hyperresponsiveness, similar to hypertonic saline challenge tests used in asthma diagnosis.

Precautions and Regulations

Sodium metal requires careful storage to prevent reactions with moisture or air. It is typically stored under an inert atmosphere, such as dry or , or submerged in , , or within tightly sealed metal containers to exclude and oxygen. Contact with or acids must be strictly avoided, as sodium reacts violently to produce gas and heat, potentially leading to fires or explosions. Safe handling of sodium demands appropriate (PPE) and controlled environments. Personnel should wear safety goggles or glasses, chemical-resistant gloves (such as leather or ), and a flame-retardant coat to protect against splashes and thermal burns. All manipulations must occur in a with the sash lowered to minimize exposure to vapors or dust, and ignition sources should be eliminated. In case of fire, Class D extinguishers containing or copper-based agents, or dry sand, are required; , , or foam must not be used, as they exacerbate the reaction. In workplace settings, sodium is classified under the standard with ratings of health 3 (serious hazard from short-term exposure), flammability 3 (ignites at most ambient temperatures), reactivity 2 (unstable or reacts violently with ), and a special W notation for water reactivity. Adequate ventilation is essential, with operations confined to well-ventilated areas or fume hoods providing at least 100 linear feet per minute of face velocity to disperse any generated fumes or particles. Transportation of sodium metal is regulated under 1428, classified as a Class 4.3 dangerous good (substances that emit flammable gases on contact with ) in Packing Group I, requiring robust, leak-proof packaging such as metal drums under inert conditions. For molten sodium, U.S. (DOT) regulations under 49 CFR Part 173 specify additional safeguards, including temperature-controlled containers and prohibitions on air , with special permits for non-standard packagings to ensure stability during transit by motor vehicle, rail, or vessel. Regulatory frameworks address sodium and its compounds to mitigate environmental and health risks. In the , the REACH regulation (EC) No. 1907/2006 requires registration and assessment of sodium compounds like through industry consortia, ensuring safe use and limiting emissions during production and handling. As of 2025, updates to the EU Batteries Regulation (EU) 2023/1542 and the European List of Waste introduce specific waste codes for certain sodium-containing batteries, such as sodium-sulphur batteries, classifying them as hazardous and mandating enhanced collection and efficiency targets for various materials (e.g., 63% for and 50% for by 2027), along with proper disposal to recover critical raw materials and prevent environmental release.

References

  1. https://pubchem.ncbi.nlm.nih.gov/element/Sodium
  2. https://periodic-table.rsc.org/element/11/sodium
  3. https://pubs.usgs.gov/sir/2017/5118/elements/Sodium/Na_txt.html
  4. https://depts.washington.edu/embryology/index.php?id=mineral
  5. https://www.livescience.com/28820-sodium.html
  6. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium
  7. https://www.webelements.com/sodium/crystal_structure.html
  8. https://periodictable.com/Properties/A/ThermalConductivity.an.html
  9. https://periodictable.com/Properties/A/ElectricalConductivity.an.html
  10. https://www-nds.iaea.org/livechart/
  11. https://www-pub.iaea.org/MTCD/Publications/PDF/te_1340_web.pdf
  12. https://www.nndc.bnl.gov/nudat3/
  13. https://atom.kaeri.re.kr/cgi-bin/nuclide?nuc=Na23
  14. https://www.sciencedirect.com/topics/chemistry/sodium
  15. https://ntrs.nasa.gov/api/citations/20030061082/downloads/20030061082.pdf
  16. https://www.osti.gov/servlets/purl/6373887
  17. https://chem.libretexts.org/Ancillary_Materials/Demos_Techniques_and_Experiments/Chemical_Safety/Reagent_Specific_Hazards/Sodium
  18. https://www.safety.pitt.edu/sites/default/files/02-005CombustibleMetals.pdf
  19. https://webbook.nist.gov/cgi/cbook.cgi?ID=C1310732&Mask=2
  20. https://www.chem.uci.edu/~unicorn/249/Handouts/RWFSodium.pdf
  21. https://pmc.ncbi.nlm.nih.gov/articles/PMC12529943/
  22. http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/electpot.html
  23. https://webbook.nist.gov/cgi/cbook.cgi?ID=C12401864&Mask=1000
  24. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-oxide
  25. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-peroxide
  26. https://www.chemicalbook.com/ChemicalProductProperty_EN_CB7853032.htm
  27. https://pubs.rsc.org/en/content/getauthorversionpdf/C6CP02286C
  28. https://srdata.nist.gov/solubility/IUPAC/SDS-11/SDS-11.pdf
  29. https://www.sciencedirect.com/science/article/abs/pii/S221334372403104X
  30. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-Hydroxide
  31. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-Carbonate
  32. https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Introductory_Chemistry_%28CK-12%29/11%253A_Chemical_Reactions/11.07%253A_Single_Replacement_Reactions
  33. https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Introduction_to_Organometallic_Chemistry_%28Ghosh_and_Balakrishna%29/02%253A_Organometallic_Chemistry_of_s-_and_p-block_Elements/2.02%253A_Organometallic_Compounds_of_Alkali_Metals_%28Sodium_and_Lithium%29
  34. https://pmc.ncbi.nlm.nih.gov/articles/PMC8487239/
  35. https://www.math.fsu.edu/~cogan/teaching/seminar/permeable.pdf
  36. https://www.sciencedirect.com/science/article/abs/pii/S095006182100026X
  37. https://pubs.acs.org/doi/10.1021/acs.inorgchem.4c02914
  38. https://www.sciencedirect.com/science/article/pii/S2451929422006052
  39. https://pubs.acs.org/doi/10.1021/acs.jpcb.9b03792
  40. https://pubs.acs.org/doi/10.1021/ic00310a023
  41. https://www.osti.gov/servlets/purl/4120472
  42. https://pubs.acs.org/doi/10.1021/acs.nanolett.3c02054
  43. https://ntrs.nasa.gov/api/citations/19710028766/downloads/19710028766.pdf
  44. https://www.si.edu/spotlight/ancient-egypt/mummies
  45. https://www.spurlock.illinois.edu/exhibits/online/mummification/materials.html
  46. https://www.etymonline.com/word/soda
  47. https://www.vanderkrogt.net/elements/element.php?sym=Na
  48. https://uwaterloo.ca/chem13-news-magazine/april-2019/feature/humphry-davy-and-voltaic-pile
  49. https://www.etymonline.com/word/sodium
  50. https://edu.rsc.org/resources/roman-glass-and-its-chemistry/1962.article
  51. https://link.springer.com/article/10.1007/s12520-016-0447-4
  52. https://www.sciencehistory.org/stories/magazine/science-and-celebrity-humphry-davys-rising-star/
  53. https://www.webelements.com/sodium/history.html
  54. https://patents.google.com/patent/US2802723A/en
  55. https://www.osti.gov/etdeweb/servlets/purl/20244555
  56. https://www.unav.es/gep/DevilleAPhysicianTurnedMetallurgist.pdf
  57. https://madar-ju.com/storage/images/files/file_1731197073iZqOJ.pdf
  58. https://www.researchgate.net/post/Castners-Process-for-sodium-production
  59. https://pubs.acs.org/doi/10.1021/cen-v026n036.p2604
  60. https://archives.sciencehistory.org/repositories/3/resources/153
  61. https://periodictable.com/Properties/A/UniverseAbundance.v.log.html
  62. https://pubs.usgs.gov/sir/2017/5118/sir20175118_element.php?el=11
  63. https://www.lenntech.com/composition-seawater.htm
  64. https://pubs.usgs.gov/periodicals/mcs2021/mcs2021_old.pdf
  65. https://www.osti.gov/servlets/purl/1645028
  66. https://iopscience.iop.org/article/10.3847/2041-8213/ac905a
  67. https://www.nature.com/articles/nature01292
  68. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/grl.50095
  69. https://ui.adsabs.harvard.edu/abs/1990ApJ...358..473W/abstract
  70. https://link.springer.com/article/10.1007/s11214-023-00952-4
  71. https://chem.libretexts.org/Bookshelves/General_Chemistry/Book%253A_General_Chemistry%253A_Principles_Patterns_and_Applications_%28Averill%29/19%253A_Electrochemistry/19.08%253A_Electrolysis
  72. https://corrosion-doctors.org/Electrowinning/Sodium.htm
  73. https://www.dynamicscience.com.au/tester/solutions1/chemistry/redox/downscell.htm
  74. https://www.sciencedirect.com/topics/chemistry/sodium-alloy
  75. https://patents.google.com/patent/US2863757A/en
  76. https://www.researchgate.net/post/Downs-Cell-Process-energy-requirements
  77. https://www.sciencedirect.com/science/article/abs/pii/S1004954125001284
  78. https://www.persistencemarketresearch.com/market-research/sodium-metal-market.asp
  79. https://www.factmr.com/report/sodium-metal-market
  80. https://en.institut-seltene-erden.de/seltene-erden-und-metalle/strategische-metalle-2/natrium/
  81. https://www.sfa-oxford.com/rare-earths-and-minor-metals/minor-metals-and-minerals/sodium-market-and-sodium-price-drivers/
  82. https://www.belfercenter.org/publication/sodium-alternative-white-gold-energy-transition
  83. https://www.sciencedirect.com/topics/engineering/kroll-process
  84. https://link.springer.com/article/10.1007/s11663-020-01898-6
  85. https://www.isu.edu/media/libraries/college-of-science-and-engineering/nuclear-engineering/documents/Sodium-Properties-Experience-and-Safety.pdf
  86. https://www.creativeengineers.com/physical-properties-of-nak
  87. https://edu.rsc.org/metallic-bonding/properties-of-alloys-finding-the-nak/2000056.article
  88. https://www.sciencedirect.com/science/article/abs/pii/S1003632609603526
  89. https://entechonline.com/how-glass-is-made-from-sand-soda-and-lime/
  90. https://chem.libretexts.org/Ancillary_Materials/Laboratory_Experiments/Wet_Lab_Experiments/General_Chemistry_Labs/Online_Chemistry_Lab_Manual/Chem_9_Experiments/12%253A_Making_Soap_-_Saponification_%28Experiment%29
  91. https://www.chlorineinstitute.org/sodium-hypochlorite
  92. https://www.globalbankingandfinance.com/global-consumption-of-sodium-metal-is-projected-to-surpass-127400-metric-tonnes-by-2024-end/
  93. https://www.cea.fr/english/Documents/scientific-and-economic-publications/nuclear-energy-monographs/CEA_Monograph7_Sodium-cooled-nuclear-reactors_2016_GB.pdf
  94. https://world-nuclear.org/information-library/current-and-future-generation/fast-neutron-reactors
  95. https://www-pub.iaea.org/MTCD/publications/PDF/CRCP_SOD_003web.pdf
  96. https://publications.anl.gov/anlpubs/2022/09/178161.pdf
  97. https://www.sciencedirect.com/topics/chemistry/sodium-sulfur-battery
  98. https://www.ngk-insulators.com/en/product/nas-about.html
  99. https://www.researchgate.net/publication/279215308_An_Experimental_Study_on_a_Sodium_Loop-type_Heat_Pipe_for_Thermal_Transport_from_a_High-temperature_Solar_Receiver
  100. https://www.ans.org/news/article-1999/seawolf-tries-sodium/
  101. https://www.navysite.de/ssn/ssn575.htm
  102. https://www.nytimes.com/1957/02/07/archives/navy-admits-leaks-in-seawolf-reactor.html
  103. https://sodiumbatteryhub.com/technical-aspects/sodium-ion-battery-components/
  104. https://www.azom.com/news.aspx?newsID=62389
  105. https://faradion.co.uk/technology-benefits/strong-performance/
  106. https://www.fastmarkets.com/insights/northvolt-first-company-outside-china-to-develop-sodium-ion-battery-with-160-wh-kg-energy-density/
  107. https://www.globenewswire.com/news-release/2025/10/09/3164228/28124/en/Sodium-Ion-Battery-Market-Analysis-and-Forecast-2025-2035-Focus-on-Application-Product-and-Regional-Analysis.html
  108. https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202510423
  109. https://www.blackridgeresearch.com/blog/list-of-global-top-sodium-na-ion-sib-battery-manufacturers-makers-companies-producers-suppliers-in-the-world
  110. https://www.sciencedirect.com/science/article/abs/pii/S0925838822043237
  111. https://www.sciencedirect.com/science/article/abs/pii/S0043135422002135
  112. https://www.chemanalyst.com/NewsAndDeals/NewsDetails/sinopec-and-lg-chem-partner-to-develop-sodium-ion-battery-materials-39887
  113. https://www.iberdrola.com/sustainability/environment/energy-efficiency/sodium-ion-batteries
  114. https://www.ncbi.nlm.nih.gov/books/NBK537088/
  115. https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf
  116. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sodium/how-much-sodium-should-i-eat-per-day
  117. https://www.who.int/news-room/fact-sheets/detail/sodium-reduction
  118. https://nutritionsource.hsph.harvard.edu/salt-and-sodium/
  119. https://www.ncbi.nlm.nih.gov/books/NBK538143/
  120. https://www.ncbi.nlm.nih.gov/books/NBK470339/
  121. https://pmc.ncbi.nlm.nih.gov/articles/PMC6770596/
  122. https://www.mayoclinic.org/diseases-conditions/hyponatremia/symptoms-causes/syc-20373711
  123. https://www.researchgate.net/publication/270287357_Potassium_Substitution_by_Sodium_in_Plants
  124. https://genomebiology.biomedcentral.com/articles/10.1186/gb-2002-3-6-reviews1017
  125. https://link.springer.com/article/10.1007/s11104-013-1801-2
  126. https://www.sciencedirect.com/science/article/pii/S1674205214600903
  127. https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.18278
  128. https://royalsocietypublishing.org/doi/10.1098/rstb.1971.0090
  129. https://pmc.ncbi.nlm.nih.gov/articles/PMC3059943/
  130. https://pmc.ncbi.nlm.nih.gov/articles/PMC11054196/
  131. https://pmc.ncbi.nlm.nih.gov/articles/PMC11073508/
  132. https://pmc.ncbi.nlm.nih.gov/articles/PMC11951978/
  133. https://www.ahajournals.org/doi/10.1161/hypertensionaha.115.05948
  134. https://www.nejm.org/doi/full/10.1056/NEJM200101043440101
  135. https://wwwn.cdc.gov/TSP/MMG/MMGDetails.aspx?mmgid=246&toxid=45
  136. https://pmc.ncbi.nlm.nih.gov/articles/PMC10715446/
  137. https://www.ccohs.ca/oshanswers/chemicals/chem_profiles/sodium_hydroxide.html
  138. https://nj.gov/health/eoh/rtkweb/documents/fs/1674.pdf
  139. https://chem.libretexts.org/Ancillary_Materials/Demos_Techniques_and_Experiments/Chemical_Safety/Reagent_Specific_Hazards/Sodium_Azide
  140. https://pmc.ncbi.nlm.nih.gov/articles/PMC8349855/
  141. https://www.cdc.gov/niosh/idlh/1310732.html
  142. https://web.stanford.edu/dept/EHS/cgi-bin/lcst/lcss/lcss77.html
  143. https://ehs.princeton.edu/book/export/html/516
  144. https://pubmed.ncbi.nlm.nih.gov/9426080/
  145. https://publications.ersnet.org/content/erj/10/11/2465.full.pdf
  146. https://ehs.princeton.edu/laboratory-research/chemical-safety/chemical-specific-protocols/sodium
  147. https://ehs.stonybrook.edu/_pdfs/standard_operating_procedure_sodium.pdf
  148. https://www.fishersci.com/store/msds?partNumber=S25556A&productDescription=SODIUM%2BMETAL%2B100G&vendorId=VN00115888&countryCode=US&language=en
  149. https://cameochemicals.noaa.gov/chemical/7794
  150. https://www.hazmattool.com/info.php?language=en&a=Sodium&b=UN1428&c=4.3
  151. https://www.sigmaaldrich.com/sds/aldrich/262714
  152. https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-C/part-173
  153. https://www.phmsa.dot.gov/hazmat/documents/offer/SP21977.pdf/offerserver/SP21977
  154. https://www.reachcentrum.eu/consortia/sodium-hydroxide-reach-consortium/
  155. https://environment.ec.europa.eu/news/battery-related-waste-codes-update-set-boost-circular-economy-2025-03-05_en
  156. https://environment.ec.europa.eu/news/new-rules-boost-recycling-efficiency-waste-batteries-2025-07-04_en
Add your contribution
Related Hubs
User Avatar
No comments yet.