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Barium, 56Ba
Barium
Pronunciation/ˈbɛəriəm/ ⓘ ​(BAIR-ee-əm)
Appearancesilvery gray; with a pale yellow tint[1]
Standard atomic weight Ar°(Ba)
Barium 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
Sr
↑
Ba
↓
Ra
caesium ← barium → lanthanum
Atomic number (Z)56
Groupgroup 2 (alkaline earth metals)
Periodperiod 6
Block  s-block
Electron configuration[Xe] 6s2
Electrons per shell2, 8, 18, 18, 8, 2
Physical properties
Phase at STPsolid
Melting point1000 K ​(727 °C, ​1341 °F)
Boiling point2118 K ​(1845 °C, ​3353 °F)
Density (at 20° C)3.594 g/cm3 [4]
when liquid (at m.p.)3.338 g/cm3
Heat of fusion7.12 kJ/mol
Heat of vaporization142 kJ/mol
Molar heat capacity28.07 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 911 1038 1185 1388 1686 2170
Atomic properties
Oxidation statescommon: +2
+1[5]
ElectronegativityPauling scale: 0.89
Ionization energies
  • 1st: 502.9 kJ/mol
  • 2nd: 965.2 kJ/mol
  • 3rd: 3600 kJ/mol
Atomic radiusempirical: 222 pm
Covalent radius215±11 pm
Van der Waals radius268 pm
Color lines in a spectral range
Spectral lines of barium
Other properties
Natural occurrenceprimordial
Crystal structure ​body-centered cubic (bcc) (cI2)
Lattice constant
Body-centered cubic crystal structure for barium
a = 502.5 pm (at 20 °C)[4]
Thermal expansion20.47×10−6/K (at 20 °C)[4]
Thermal conductivity18.4 W/(m⋅K)
Electrical resistivity332 nΩ⋅m (at 20 °C)
Magnetic orderingparamagnetic[6]
Molar magnetic susceptibility+20.6×10−6 cm3/mol[7]
Young's modulus13 GPa
Shear modulus4.9 GPa
Bulk modulus9.6 GPa
Speed of sound thin rod1620 m/s (at 20 °C)
Mohs hardness1.25
CAS Number7440-39-3
History
Namingfrom Greek βαρὺς (barys), meaning 'heavy'
DiscoveryCarl Wilhelm Scheele (1772)
First isolationHumphry Davy (1808)
Isotopes of barium
Main isotopes[8] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
130Ba 0.11% (0.5–2.7)×1021 y εε 130Xe
131Ba synth 11.52 d β+ 131Cs
132Ba 0.1% stable
133Ba synth 10.538 y ε 133Cs
134Ba 2.42% stable
135Ba 6.59% stable
136Ba 7.85% stable
137Ba 11.2% stable
138Ba 71.7% stable
140Ba synth 12.753 d β− 140La
 Category: Barium
| references

Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element.

The most common minerals of barium are barite (barium sulfate, BaSO4) and witherite (barium carbonate, BaCO3). The name barium originates from the alchemical derivative "baryta" from Greek βαρὺς (barys), meaning 'heavy'. Baric is the adjectival form of barium. Barium was identified as a new element in 1772, but not reduced to a metal until 1808 with the advent of electrolysis.

Barium has few industrial applications. Historically, it was used as a getter for vacuum tubes and in oxide form as the emissive coating on indirectly heated cathodes. It is a component of YBCO (high-temperature superconductors) and electroceramics, and is added to steel and cast iron to reduce the size of carbon grains within the microstructure. Barium compounds are added to fireworks to impart a green color. Barium sulfate is used as an insoluble additive to oil well drilling fluid. In a purer form it is used as X-ray radiocontrast agents for imaging the human gastrointestinal tract. Water-soluble barium compounds are poisonous and have been used as rodenticides.

Characteristics

[edit]

Physical properties

[edit]
Oxidized barium

Barium is a soft, silvery-white metal, with a slight golden shade when ultrapure.[9]: 2  The silvery-white color of barium metal rapidly vanishes upon oxidation in air yielding a dark gray layer containing the oxide. Barium has a medium specific weight and high electrical conductivity. Because barium is difficult to purify, many of its properties have not been accurately determined.[9]: 2 

At room temperature and pressure, barium metal adopts a body-centered cubic structure, with a barium–barium distance of 503 picometers, expanding with heating at a rate of approximately 1.8×10−5/°C.[9]: 2  It is a soft metal with a Mohs hardness of 1.25.[9]: 2  Its melting temperature of 1,000 K (730 °C; 1,340 °F)[10]: 4–43  is intermediate between those of the lighter strontium (1,050 K or 780 °C or 1,430 °F)[10]: 4–86  and heavier radium (973 K or 700 °C or 1,292 °F);[10]: 4–78  however, its boiling point of 2,170 K (1,900 °C; 3,450 °F) exceeds that of strontium (1,655 K or 1,382 °C or 2,519 °F).[10]: 4–86  The density (3.62 g/cm3)[10]: 4–43  is again intermediate between those of strontium (2.36 g/cm3)[10]: 4–86  and radium (≈5 g/cm3).[10]: 4–78 

Chemical reactivity

[edit]

Barium is chemically similar to magnesium, calcium, and strontium, but more reactive. Its compounds are almost invariably found in the +2 oxidation state. As expected for a highly electropositive metal, barium's reaction with chalcogens is highly exothermic (release energy). Barium reacts with atmospheric oxygen in air at room temperature. For this reason, metallic barium is often stored under oil or in an inert atmosphere.[9]: 2  Reactions with other nonmetals, such as carbon, nitrogen, phosphorus, silicon, and hydrogen, proceed upon heating.[9]: 2–3  Reactions with water and alcohols are also exothermic and release hydrogen gas:[9]: 3 

Ba + 2 ROH → Ba(OR)2 + H2↑ (R is an alkyl group or a hydrogen atom)

Barium reacts with ammonia to form the electride [Ba(NH3)6](e−)2, which near room temperature gives the amide Ba(NH2)2.[11]

The metal is readily attacked by acids. Sulfuric acid is a notable exception because passivation stops the reaction by forming the insoluble barium sulfate on the surface.[12] Barium combines with several other metals, including aluminium, zinc, lead, and tin, forming intermetallic phases and alloys.[13]

Compounds

[edit]
Selected alkaline earth and zinc salts densities, g/cm3
O2− S2− F− Cl− SO2−4 CO2−3 O2−2 H−
Ca2+[10]: 4–48–50  3.34 2.59 3.18 2.15 2.96 2.83 2.9 1.7
Sr2+[10]: 4–86–88  5.1 3.7 4.24 3.05 3.96 3.5 4.78 3.26
Ba2+[10]: 4–43–45  5.72 4.3 4.89 3.89 4.49 4.29 4.96 4.16
Zn2+[10]: 4–95–96  5.6 4.09 4.95 2.91 3.54 4.4 1.57 —

Barium salts are typically white when solid and colorless when dissolved.[14] They are denser than the strontium or calcium analogs (see table; zinc is given for comparison).

Barium hydroxide ("baryta") was known to alchemists, who produced it by heating barium carbonate. Unlike calcium hydroxide, it absorbs very little CO2 in aqueous solutions and is therefore insensitive to atmospheric fluctuations. This property is used in calibrating pH equipment.

Barium compounds burn with a green to pale green flame, which is an efficient test to detect a barium compound. The color results from spectral lines at 455.4, 493.4, 553.6, and 611.1 nm.[9]: 3 

Organobarium compounds are a growing field of knowledge: recently discovered are dialkylbariums and alkylhalobariums.[9]: 3 

Isotopes

[edit]
Main article: Isotopes of barium
All nuclear data not otherwise stated is from the standard source:[15]

Barium found in the Earth's crust is a mixture of seven primordial nuclides, barium-130, 132, and 134 through 138. Barium-130 undergoes very slow radioactive decay to xenon-130 by double beta plus decay, with a half-life of (0.5–2.7)×1021 years (about 1011 times the age of the universe). Its abundance is about 0.11% that of natural barium. Though barium-132 can theoretically undergo the same decay, giving xenon-132, experimental evidence has not detected this.

Of the stable isotopes, barium-138 composes 71.7% of all barium; other isotopes have decreasing abundance with decreasing mass number (except for a probable inversion for the p-nuclei 130Ba and 132Ba).

In total, barium has 41 known isotopes, ranging in mass between 114 and 154. The most stable artificial radioisotope is barium-133 with a half-life of 10.538 years. Five other isotopes have half-lives longer than a day. The longest-lived isomers are 133mBa at 38.90 hours and 135m1Ba at 28.11 hours. The analogous 137m1Ba (half-life 2.552 minutes) occurs in the decay of the common fission product caesium-137.


History

[edit]
Portrait of Sir Humphry Davy by Thomas Lawrence, 1821. Sir Humphry Davy was the first to isolate barium metal.

Alchemists in the early Middle Ages knew about some barium minerals. Smooth pebble-like stones of mineral baryte were found in volcanic rock near Bologna, Italy, and so were called "Bologna stones". Alchemists were attracted to them because after exposure to light they would glow for years.[16] The phosphorescent properties of baryte heated with organics were described by V. Casciorolus in 1602.[9]: 5 

Carl Scheele determined that baryte contained a new element in 1772, but could not isolate barium, only barium oxide. Johan Gottlieb Gahn also isolated barium oxide two years later in similar studies. Oxidized barium was at first called "barote" by Guyton de Morveau, a name that was changed by Antoine Lavoisier to baryte (in French) or baryta (in Latin). Also in the 18th century, English mineralogist William Withering noted a heavy mineral in the lead mines of Cumberland, now known to be witherite. Barium was first isolated by electrolysis of molten barium salts in 1808 by Sir Humphry Davy in England.[17] Davy, by analogy with calcium, named "barium" after baryta, with the "-ium" ending signifying a metallic element.[16] Robert Bunsen and Augustus Matthiessen obtained pure barium by electrolysis of a molten mixture of barium chloride and ammonium chloride.[18][19]

The production of pure oxygen in the Brin process was a large-scale application of barium peroxide in the 1880s, before it was replaced by electrolysis and fractional distillation of liquefied air in the early 1900s. In this process barium oxide reacts at 500–600 °C (932–1,112 °F) with air to form barium peroxide, which decomposes above 700 °C (1,292 °F) by releasing oxygen:[20][21]

2 BaO + O2 ⇌ 2 BaO2

Barium sulfate was first applied as a radiocontrast agent in X-ray imaging of the digestive system in 1908.[22]

Occurrence and production

[edit]

The abundance of barium is 0.0425% in the Earth's crust and 13 μg/L in sea water. The primary commercial source of barium is baryte (also called barytes or heavy spar), a barium sulfate mineral.[9]: 5  with deposits in many parts of the world. Another commercial source, far less important than baryte, is witherite, barium carbonate. The main deposits are located in Britain, Romania, and the former USSR.[9]: 5 

alt1
alt2
alt3
Barite, left to right: appearance, graph showing trends in production over time, and the map showing shares of the most important producer countries in 2010.

The baryte reserves are estimated between 0.7 and 2 billion tonnes. The highest production, 8.3 million tonnes, was achieved in 1981, but only 7–8% was used for barium metal or compounds.[9]: 5  Baryte production has risen since the second half of the 1990s from 5.6 million tonnes in 1996 to 7.6 in 2005 and 7.8 in 2011. China accounts for more than 50% of this output, followed by India (14% in 2011), Morocco (8.3%), US (8.2%), Iran and Kazakhstan (2.6% each) and Turkey (2.5%).[23]

The mined ore is washed, crushed, classified, and separated from quartz. If the quartz penetrates too deeply into the ore, or the iron, zinc, or lead content is abnormally high, then froth flotation is used. The product is a 98% pure baryte (by mass); the purity should be no less than 95%, with a minimal content of iron and silicon dioxide.[9]: 7  It is then reduced by carbon to barium sulfide:[9]: 6 

BaSO4 + 2 C → BaS + 2 CO2

The water-soluble barium sulfide is the starting point for other compounds: treating BaS with oxygen produces the sulfate, with nitric acid the nitrate, with aqueous carbon dioxide the carbonate, and so on.[9]: 6  The nitrate can be thermally decomposed to yield the oxide.[9]: 6  Barium metal is produced by reduction with aluminium at 1,100 °C (2,010 °F). The intermetallic compound BaAl4 is produced first:[9]: 3 

3 BaO + 14 Al → 3 BaAl4 + Al2O3

The remaining barium oxide reacts with the aluminium oxide formed...[9]: 3 

BaO + Al2O3 → BaAl2O4

...and the overall reaction is:[9]: 3 

4 BaO + 2 Al → 3 Ba↓ + BaAl2O4

Note that not all barium is reduced.[9]: 3 

Barium vapor is condensed and packed into molds in an atmosphere of argon.[9]: 3  This method is used commercially, yielding ultrapure barium.[9]: 3  Commonly sold barium is about 99% pure, with main impurities being strontium and calcium (up to 0.8% and 0.25%) and other contaminants contributing less than 0.1%.[9]: 4 

A similar reaction with silicon at 1,200 °C (2,190 °F) yields barium and barium metasilicate.[9]: 3  Electrolysis is not used because barium readily dissolves in molten halides and the product is rather impure.[9]: 3 

Benitoite crystals on natrolite. The mineral is named for the San Benito River in San Benito County where it was first found.

Gemstone

[edit]

The barium mineral, benitoite (barium titanium silicate), occurs as a very rare blue fluorescent gemstone, and is the official state gem of California.

Barium in seawater

[edit]

Barium exists in seawater as the Ba2+ ion with an average oceanic concentration of 109 nmol/kg.[24] Barium also exists in the ocean as BaSO4, or barite.[25] Barium has a nutrient-like profile[26] with a residence time of 10,000 years.[24]

Barium shows a relatively consistent concentration in upper ocean seawater, excepting regions of high river inputs and regions with strong upwelling.[27] There is little depletion of barium concentrations in the upper ocean for an ion with a nutrient-like profile, thus lateral mixing is important.[27] Barium isotopic values show basin-scale balances instead of local or short-term processes.[27]

Applications

[edit]

Metal and alloys

[edit]

Barium, as a metal or when alloyed with aluminium, is used to remove unwanted gases (gettering) from vacuum tubes, such as TV picture tubes.[9]: 4  Barium is suitable for this purpose because of its low vapor pressure and reactivity towards oxygen, nitrogen, carbon dioxide, and water; it can even partly remove noble gases by dissolving them in the crystal lattice. This application has gradually disappeared due to the popularity of the tubeless LCD, LED, and plasma sets.[9]: 4 

Other uses of elemental barium are minor and include an additive to silumin (aluminium–silicon alloys) that refines their structure, as well as[9]: 4 

Barium sulfate and baryte

[edit]
Amoebiasis as seen in a radiograph of a barium-filled colon

Barium sulfate (the mineral baryte, BaSO4) is important to the petroleum industry as a drilling fluid in oil and gas wells.[10]: 4–5  The precipitate of the compound (called "blanc fixe", from the French for "permanent white") is used in paints and varnishes; as a filler in ringing ink, plastics, and rubbers; as a paper coating pigment; and in nanoparticles, to improve physical properties of some polymers, such as epoxies.[9]: 9 

Barium sulfate has a low toxicity and relatively high density of ca. 4.5 g/cm3 (and thus opacity to X-rays). For this reason it is used as a radiocontrast agent in X-ray imaging of the digestive system ("barium meals" and "barium enemas").[10]: 4–5  Lithopone, a pigment that contains barium sulfate and zinc sulfide, is a permanent white with good covering power that does not darken when exposed to sulfides.[28]

Other barium compounds

[edit]
Green barium fireworks

Other compounds of barium find only niche applications, limited by the toxicity of Ba2+ ions (see § Toxicity), which is not a problem for the insoluble BaSO4.

Palaeoceanography

[edit]

The lateral mixing of barium is caused by water mass mixing and ocean circulation.[34] Global ocean circulation reveals a strong correlation between dissolved barium and silicic acid.[34] The large-scale ocean circulation combined with remineralization of barium show a similar correlation between dissolved barium and ocean alkalinity.[34]

Dissolved barium's correlation with silicic acid can be seen both vertically and spatially.[35] Particulate barium shows a strong correlation with particulate organic carbon or POC.[35] Barium is becoming more popular as a base for palaeoceanographic proxies.[35] With both dissolved and particulate barium's links with silicic acid and POC, it can be used to determine historical variations in the biological pump, carbon cycle, and global climate.[35]

The barium particulate barite (BaSO4), as one of many proxies, can be used to provide a host of historical information on processes in different oceanic settings (water column, sediments, and hydrothermal sites).[25] In each setting there are differences in isotopic and elemental composition of the barite particulate.[25] Barite in the water column, known as marine or pelagic barite, reveals information on seawater chemistry variation over time.[25] Barite in sediments, known as diagenetic or cold seeps barite, gives information about sedimentary redox processes.[25] Barite formed via hydrothermal activity at hydrothermal vents, known as hydrothermal barite, reveals alterations in the condition of the earth's crust around those vents.[25]

Toxicity

[edit]
Barium
Hazards
GHS labelling:[36]
GHS02: Flammable GHS05: Corrosive GHS06: Toxic
Danger
H228, H260, H301, H314
P210, P231+P232, P260, P280, P303+P361+P353, P304+P340+P310, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
3
1
W

Soluble barium compounds have an LD50 near 10 mg/kg (oral, rats). Symptoms include "convulsions... paralysis of the peripheral nerve system ... severe inflammation of the gastrointestinal tract".[9]: 18  The insoluble sulfate is nontoxic and is not classified as a dangerous goods in transport regulations.[9]: 9 

Little is known about the long term effects of barium exposure.[37] The US EPA considers it unlikely that barium is carcinogenic when consumed orally. Inhaled dust containing insoluble barium compounds can accumulate in the lungs, causing a benign condition called baritosis.[38]

Barium carbonate has been used as a rodenticide.[39] Though considered obsolete, it may still be in use in some countries.[40]

See also

[edit]

References

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

Barium

View on Grokipedia
from Grokipedia
Barium is a with the symbol Ba and 56, classified as an in group 2 of the periodic table. It appears as a soft, silvery-white metal that is highly reactive, rapidly oxidizing in air to form a dark layer and reacting vigorously with water to produce hydrogen gas and . Due to this reactivity, barium does not occur in its free elemental form in but is found in combined states, primarily in the minerals barite (, BaSO4) and witherite (, BaCO3). The element was first isolated in pure form in 1808 by English chemist Sir Humphry Davy through the of molten (baryta), following earlier recognition of barium compounds by Carl Scheele in 1774. Barium's chemical behavior closely resembles that of calcium and , its fellow alkaline earth metals, due to similar electron configurations, though it exhibits greater reactivity. Its atomic weight is 137.327, and it has seven stable isotopes, with barium-138 being the most abundant at about 71.66%. Barium and its compounds have diverse industrial applications, leveraging properties like high density and chemical reactivity. Barite, the most common barium mineral, serves as a weighting agent in and gas drilling muds to control pressure and prevent blowouts, accounting for over 90% of U.S. barite consumption. Soluble barium salts produce a characteristic color in and , while barium is used in as a radiopaque for gastrointestinal X-rays due to its insolubility and low toxicity. Other uses include barium in ceramics, glass manufacturing, and rat poisons, as well as barium compounds in paints, plastics, and rubber production for stabilization and pigmentation. However, soluble barium compounds are toxic, causing symptoms like , , and gastrointestinal distress upon or , necessitating careful handling.

Properties

Physical properties

Barium is a soft, silvery-white that can be cut with a due to its low . Upon exposure to air, it rapidly oxidizes, forming a dark gray to layer on its surface that protects the underlying metal from further rapid . The of barium is 3.51 g/cm³ at 20°C, positioning it among the denser stable elements relative to lighter alkaline earth metals. It melts at 727°C and boils at 1897°C, exhibiting typical metallic phase behavior with a relatively low for a heavy metal. Barium adopts a body-centered cubic (bcc) at , with lattice parameter a ≈ 502.8 pm. Barium demonstrates high electrical conductivity, with a specific resistivity of approximately 3.32 × 10⁻⁷ Ω·m at 20°C, comparable to other and alkaline earth metals. Its thermal properties include a linear coefficient of 20.6 × 10⁻⁶ ⁻¹ and a molar specific heat capacity of 28.07 J/(mol·) at 25°C. Although insoluble in , barium reacts vigorously with it, producing gas and .

Chemical properties

Barium possesses an of 56 and an of [Xe] 6s², which includes two valence electrons that typically yield a +2 in its chemical compounds. The element exhibits an of 0.89 on the Pauling scale, consistent with its classification as an . Its first is 502.9 kJ/mol, and the second is 965.2 kJ/mol, values that highlight the relative ease of removing its outer s electrons compared to inner-shell electrons. Barium displays high reactivity, igniting spontaneously upon exposure to air owing to its strong reducing nature and affinity for oxygen. It also reacts vigorously with water, liberating hydrogen gas and forming barium hydroxide, as represented by the balanced equation: \ceBa+2H2O−>Ba(OH)2+H2\ce{Ba + 2H2O -> Ba(OH)2 + H2} This behavior positions barium as one of the more reactive members of group 2 in the periodic table./Descriptive_Chemistry/Elements_Organized_by_Block/1_s-Block_Elements/Group__2_Elements:_The_Alkaline_Earth_Metals/1Group_2:_Chemical_Reactions_of_Alkali_Earth_Metals/Reactions_of_Group_2_Elements_with_Water) As a , barium surpasses magnesium in strength, evidenced by its more negative of -2.912 for the Ba²⁺/Ba couple versus -2.372 for Mg²⁺/Mg, though it is comparable to sodium at -2.714 for Na⁺/Na. This electrochemical profile enables its application in organometallic synthesis, where it serves as a potent reductant for generating low-valent barium and related complexes under mild conditions. The Ba²⁺ ion's large of 1.35 Å contributes to the formation of predominantly ionic compounds, characterized by lower than those of analogous compounds with smaller group 2 cations; this arises from the inverse relationship between interionic distance and magnitude./08:_Ionic_versus_Covalent_Bonding/8.03:_Lattice_Energies_in_Ionic_Solids) Post-2020 computational investigations have examined barium's incorporation into high-entropy configurations, such as in superhydride systems like BaH₁₂, revealing potential for elevated superconducting transition temperatures under high pressure due to enhanced electron-phonon coupling in these disordered structures.

Isotopes

Barium has 35 known isotopes, with mass numbers ranging from ¹¹³Ba to ¹⁵³Ba. Of these, seven are and constitute the naturally occurring isotopic composition of barium, while the remainder are radioactive with half-lives generally shorter than two weeks, except for a few longer-lived ones. The stable isotopes and their natural abundances are listed in the following table:
IsotopeNatural Abundance (%)
¹³⁰Ba0.11
¹³²Ba0.10
¹³⁴Ba2.42
¹³⁵Ba6.59
¹³⁶Ba7.85
¹³⁷Ba11.23
¹³⁸Ba71.70
Among the radioactive isotopes, ¹³³Ba has the longest at 10.539(6) years and decays primarily by to stable ¹³³Cs, with principal gamma emissions at 80 keV, 303 keV, and 356 keV. It is produced through on stable barium isotopes in nuclear reactors and serves as a standard for detection equipment due to its well-characterized gamma and suitable half-life for laboratory use. Another notable is ¹⁴⁰Ba, with a of 12.75 days, which undergoes beta-minus decay to ¹⁴⁰La and is utilized in , particularly in applications for imaging and therapy owing to its daughter product's emissions. Barium isotopes play a key role in and . The isotopic ratio ¹³⁰Ba/¹³⁶Ba in provides insights into , serving as a for dust formation timelines in core-collapse supernovae by distinguishing s-process and r-process contributions. Additionally, stable ¹³⁷Ba is the end product of the ¹³⁷Cs , where ¹³⁷Cs ( 30.17 years) beta-decays to metastable ¹³⁷mBa, which then emits a 662 keV before reaching stable ¹³⁷Ba; this chain is monitored in environmental assessments following nuclear events. Nuclear properties of barium isotopes highlight their astrophysical significance. ¹³⁸Ba acts as an endpoint nuclide in the slow neutron-capture process (s-process), where neutron capture and beta decay terminate at this stable isotope due to its low neutron-capture cross-section, influencing the production of heavier elements in asymptotic giant branch stars. Recent astrophysical observations from 2023 to 2025 have leveraged barium isotopic ratios in metal-poor stars to trace heavy element formation, providing constraints on neutron star mergers as r-process sites and linking gravitational wave events like GW170817 to galactic chemical evolution.

History

Discovery and isolation

In 1774, Swedish chemist identified a new "heavy earth," termed terra ponderosa (Latin for heavy earth), while analyzing the mineral heavy spar, now known as barite or (BaSO₄). Scheele distinguished this substance from lime (calcium oxide, CaO), noting its greater density and distinct chemical properties during experiments involving the reduction of . Building on this, German chemist contributed to the characterization of barium compounds in the late 18th century. In 1793, Klaproth published methods for separating from barium salts, further clarifying the distinct nature of baryta through analytical techniques, including precipitation and . The element barium itself was first isolated in pure form in 1808 by British chemist Sir Humphry Davy at the Royal Institution in . Davy achieved this through of molten baryta () using a mercury , which produced a barium-mercury amalgam. The amalgam was then heated to distill off the mercury, yielding impure metallic barium. Davy named the element "barium" after the Greek word barys, meaning "heavy," reflecting the density of its compounds.

Early industrial development

The commercialization of barium began in the early with the mining of barite () primarily for use as a white in paints and fillers. Commercial barite started in and in the early 1800s, followed by in 1835, driven by the growing demand for high-density, inert white materials during industrialization. Barite's adoption as a pigment in the West occurred around this time, valued for its brightness and opacity in artistic and industrial applications. Early industrial processes focused on barium compounds rather than the metal itself, with significant advancements in the mid-19th century. emerged as a key for acid dyes in dyeing, aiding in color fixation on fabrics and enabling more vibrant, durable results amid the rise of synthetic dyes. By the 1870s, found application in , where it served as an oxidizer to produce brilliant green flames, enhancing and signal flares during a period of expanding recreational and military uses. Key milestones included the establishment of the U.S. barite industry in during the 1880s, where deposits in the southeast region supported growing domestic needs for pigments and chemicals; led national production from 1885 onward. In the 1890s, gained traction as a bleaching agent for textiles and other materials. By the , barium was employed in vacuum tubes as a getter material to maintain high vacuums by absorbing residual gases, a critical innovation for early radio and amid overlooked environmental considerations in historical assessments. Efforts to produce pure barium metal faced persistent challenges from impurities in early reduction methods, such as electrolysis of or aluminothermic reduction, which often yielded contaminated products unsuitable for advanced applications. These issues persisted until , when vacuum distillation techniques enabled higher-purity barium by volatilizing and separating impurities like metals at reduced pressures.

Occurrence

Terrestrial sources

Barium is a relatively abundant element in the , comprising approximately 0.0425% by weight and ranking 14th in elemental abundance. This concentration places it behind common elements like oxygen, , and aluminum but ahead of rarer ones such as and . The element occurs primarily in mineral forms, with barite (BaSO₄) serving as the dominant source, accounting for roughly 77% of global barium production. (BaCO₃) contributes about 3%, while lesser minerals like hyalophane (a barium ) provide minor amounts. These minerals form through sedimentary and hydrothermal processes, with barite often crystallizing in veins or beds due to its low in aqueous environments. Major terrestrial deposits are concentrated in several regions, with holding approximately 35% of known global reserves, primarily in the southern and Jiangnan areas (110 million tons as of 2025). and follow as significant holders, the latter featuring extensive sedimentary-hosted barite in the High region. In the United States, identified resources total 150 million tons (reserves not separately estimated), mainly in Nevada's barite districts and Missouri's residual deposits from weathered . Barium minerals frequently associate with sulfides such as and within formations, reflecting their precipitation in reducing environments. (BaTiSi₃O₉), a rare blue containing barium, occurs notably in hydrothermally altered in . Geochemically, barium exhibits low mobility during , as it binds to iron oxides and clay minerals, limiting its transport in soils. This immobility promotes its accumulation in sequences, where barite forms through sulfate precipitation in arid basins.

Marine and extraterrestrial occurrence

Barium occurs in marine environments primarily as dissolved Ba²⁺ ions, with concentrations in typically ranging from 4 to 20 µg/L. This dissolved form is largely associated with , existing in equilibrium with barite (BaSO₄) , which limits higher concentrations to approximately 37–52 µg/L at 25°C and 1 atm. Vertical profiles of dissolved barium in the exhibit nutrient-like , with depletion in surface waters due to biological uptake and remineralization, and enrichment in deeper layers from particle regeneration. The main sources of barium to the oceans include riverine input from continental weathering and hydrothermal vents at mid-ocean ridges. Rivers deliver barium primarily as dissolved ions and particulates from barite-rich soils, contributing to coastal and open-ocean inventories. Hydrothermal vent fluids are significantly enriched in barium, up to several hundred µg/L, though much precipitates as barite upon mixing with sulfate-rich seawater, adding to deep-sea particulate fluxes. In marine sediments, microcrystals of authigenic barite accumulate as a proxy for paleoproductivity, reflecting organic carbon export from surface waters. These microcrystals form in microenvironments within organic aggregates in the and preserve in sediments with minimal diagenetic alteration, allowing reconstruction of past export production rates. Barite accumulation rates correlate with availability and primary in overlying waters. In paleoceanography, Ba/Ca ratios preserved in foraminiferal shells serve as tracers for reconstructing ancient circulation patterns. incorporate barium in proportion to Ba/Ca, which varies with runoff and distributions, enabling inferences about past hydrographic conditions near estuaries. further record bottom-water barium levels influenced by ventilation and oxygen minimum zones, linking to deep circulation changes. Atmospheric barium derives mainly from aeolian dust transport and anthropogenic pollution, with concentrations in ambient air typically below 1 µg/m³ near emission sources. from barite-bearing regions contributes to global loading, while industrial emissions, such as from fluids, elevate local levels. particles in aerosols participate in climate studies as components of stratospheric sulfate layers, influencing through scattering. Extraterrestrially, barium is present in lunar at concentrations around 50–170 ppm in Apollo mission samples, reflecting basaltic and impact-derived compositions. In meteorites, carbonaceous chondrites contain barium at 2–6 ppm, with isotopic variations indicating presolar nucleosynthetic origins. Barium lines, particularly in barium stars, reveal enhancements from nucleosynthesis in stars, tracing heavy element production in galactic .

Production

Extraction from ores

Barium is primarily extracted from barite (BaSO₄) ores through operations that target shallow and deeper deposits. is commonly used for shallow barite deposits near the surface, involving the removal of with heavy machinery such as excavators and haul trucks to access the ore body. For deeper vein deposits, underground methods are employed, utilizing techniques like room-and-pillar or cut-and-fill to extract ore while maintaining structural stability. Global barite production reached approximately 8.2 million metric tons in 2024, driven by demand in drilling fluids and industrial applications, with major producers including , , and . Barite occurs in two primary ore types relevant to extraction: bedded sedimentary deposits, formed in marine environments through , and replacement deposits, where barite replaces host rocks like in hydrothermal settings. Bedded deposits are typically tabular and easier to mine via open-pit methods, while replacement deposits often form irregular veins suited to underground extraction. Common impurities in these ores include iron oxides, silica (as ), and , which must be managed to avoid contamination in . Following extraction, beneficiation begins with crushing the to reduce , followed by grinding to liberate barite crystals from materials. is then applied, using collectors like sodium oleate to selectively float barite particles, achieving concentrates with over 90% BaSO₄ purity. Gravity separation, leveraging barite's high (specific gravity 4.2–4.6), is also utilized via jigs or shaking tables to separate it from lighter impurities, often in combination with flotation for optimal recovery. Environmental considerations in barite extraction focus on mitigating generation and managing rock. Dust control measures, such as sprays and enclosed conveyor systems, are essential during , blasting, and hauling to prevent respiratory hazards and airborne particulate spread. rock management involves stockpiling and revegetation to minimize and land disturbance, with barium's low environmental mobility reducing leaching risks near mine sites. In , a major barite producer, the revised Mineral Resources Law (effective July 1, 2025) mandates ecological restoration plans prior to , emphasizing sustainable techniques like pollution prevention and protection to address . Byproduct recovery enhances economic viability, particularly from associated minerals in polymetallic deposits. Fluorite (CaF₂) and zinc sulfides are often recovered alongside barite through selective flotation, with historical U.S. operations yielding these as valuable co-products from fluorspar and lead-zinc mines.

Industrial refining processes

The industrial refining of barium from beneficiated barite concentrate involves a series of chemical and metallurgical steps to yield pure metal or compounds, starting with the processed ore as feedstock. Barite (BaSO₄) undergoes roasting via thermal decomposition at 800–1000°C to form barium oxide (BaO), which serves as an intermediate for metal production. A common route for barium metal involves aluminothermic reduction of BaO using aluminum at elevated temperatures (around 1100°C) in a , generating barium vapor that is condensed to solid metal; this process is energy-intensive but effective for commercial-scale output. For high-purity applications, electrolytic production employs of (BaCl₂) at approximately 800–900°C, yielding barium metal with purity exceeding 99.9% through cathodic deposition. Barium compounds are refined via targeted precipitation and reaction sequences. Precipitated (BaSO₄) is obtained by mixing aqueous solutions of (BaCl₂) and (Na₂SO₄), resulting in immediate formation of fine BaSO₄ particles that are filtered, washed, and dried to achieve high whiteness and purity for industrial fillers. (BaCO₃) is produced through a variant, where (BaS, derived from prior coke reduction of barite) reacts with (Na₂CO₃) solution or is carbonated with CO₂ gas, precipitating BaCO₃ for use in ceramics and . In small-scale operations, the aluminum thermite method offers a simpler alternative for barium metal, utilizing the exothermic reaction 3BaO + 2Al → 3Ba + Al₂O₃ to achieve rapid reduction without large furnaces.

Compounds

Barium sulfate

Barium sulfate, with the chemical formula BaSO4BaSO_4, is the most prevalent and stable compound of barium, occurring naturally as the mineral barite. It adopts an orthorhombic crystal structure, characterized by lattice parameters a=8.896a = 8.896 Å, b=5.462b = 5.462 Å, and c=7.171c = 7.171 Å. The compound exhibits a density of 4.50 g/cm³ and is virtually insoluble in water, with a solubility product constant Ksp=1.1×10−10K_{sp} = 1.1 \times 10^{-10} at 25°C, which underscores its low solubility of approximately 0.00024 g/100 mL at 20°C. Preparation of barium sulfate typically involves the precipitation reaction of a soluble barium salt, such as , with a sulfate source like : BaCl2+Na2SO4→BaSO4↓+2NaClBaCl_2 + Na_2SO_4 \rightarrow BaSO_4 \downarrow + 2NaCl. This method yields a highly pure precipitate suitable for use. In nature, it is mined directly as barite ore, which constitutes the primary commercial source. Physically, barium sulfate manifests as a white to yellowish, odorless powder, prized for its opacity arising from a high of approximately 1.64, enabling its role in light-scattering applications. The compound demonstrates exceptional thermal stability, decomposing only at 1580°C into and : BaSO4→BaO+SO3BaSO_4 \rightarrow BaO + SO_3. Due to its extreme insolubility, is non-toxic and does not release bioavailable barium ions, in stark contrast to soluble barium salts that can induce toxicity. This property renders it safe for ingestion in medical contexts. In , serves as the standard precipitate in for ion determination, where sulfate-containing samples are treated with excess to form the insoluble BaSO4BaSO_4, which is then filtered, dried, and weighed to quantify content. Recent advancements include 2023 formulations of barium-doped mesoporous silica nanoparticles (<50 nm), which enhance X-ray attenuation for improved computed tomography (CT) contrast while maintaining biocompatibility due to the inherent insolubility of the core material.

Other barium compounds

Barium carbonate (BaCO₃) is a white solid that exhibits low solubility in water, with a solubility product constant (Ksp) of 5.1 × 10−9 at 25°C, making it sparingly soluble under neutral conditions. It is typically prepared through the carbonation of barium hydroxide by bubbling carbon dioxide gas into an aqueous solution of Ba(OH)2, yielding BaCO3 precipitate via the reaction Ba(OH)2 + CO2 → BaCO3 + H2O. This compound serves as a key precursor for synthesizing other barium salts due to its relative stability and ease of conversion. Barium oxide (BaO) is a white to yellowish, hygroscopic powder that behaves as a strong basic oxide, readily reacting with water to form barium hydroxide and exhibiting basic properties in reactions with acids. It is produced industrially via the thermal decomposition of barium carbonate at elevated temperatures (above 800°C), following the equation BaCO3 → BaO + CO2. Notably, BaO reacts with carbon dioxide in the atmosphere to regenerate barium carbonate, as in BaO + CO2 → BaCO3, which underscores its role in reversible carbonate-oxide cycles. Barium chloride (BaCl2) exists commonly as the dihydrate (BaCl2·2H2O), a colorless crystalline solid with high solubility of 35.8 g per 100 mL at 20°C, reflecting its ionic nature and dissociation into Ba2+ and Cl− ions. It is synthesized by dissolving in , producing the soluble chloride alongside and : BaCO3 + 2HCl → BaCl2 + CO2 + H2O. Barium nitrate (Ba(NO3)2) adopts a cubic and is highly soluble in (approximately 9 g/100 mL at 20°C), functioning as a strong due to the group's ability to release oxygen. Preparation involves dissolving in , with filtration to remove impurities and subsequent for : BaCO3 + 2HNO3 → Ba(NO3)2 + CO2 + H2O. Its cubic lattice consists of Ba2+ cations coordinated by nitrate anions, contributing to its stability and . Among barium organometallics, barium acetylide (BaC2) is notable for its use in , particularly in forming carbon-carbon bonds via reactions with electrophiles, akin to other alkaline earth acetylides. It is prepared by reacting barium metal with in liquid , yielding a crystalline powder. However, its stability is limited by high reactivity toward moisture and oxygen, as well as low in organic solvents, necessitating inert handling conditions. Barium titanate (BaTiO3) exemplifies advanced perovskite-structured compounds, where the ABO3 framework features Ba2+ at A-sites and Ti4+ at B-sites, enabling ferroelectric properties through Ti displacement. Recent variants, such as nonstoichiometric tin-doped BaTiO3, have been developed in 2024 to achieve ultrahigh piezoelectric coefficients (up to 825 pC/N) by optimizing defect structures and phase boundaries, enhancing suitability for electronic devices like sensors. These doped perovskites maintain the cubic-to-tetragonal but exhibit improved electromechanical coupling via controlled .

Applications

Industrial and material uses

Barium sulfate, commonly known as barite, serves as a primary weighting agent in fluids for oil and wells, accounting for approximately 80-90% of global barite consumption. This application leverages barite's high specific gravity of 4.2-4.5 g/cm³ to increase mud density up to 2.5 g/cm³, helping to control formation pressures, prevent blowouts, and stabilize wellbores during operations. In pigments and fillers, precipitated barium sulfate, or blanc fixe, is widely used in paints, coatings, and plastics to provide opacity, brightness, and corrosion resistance. Its inert nature and fine particle size make it an effective extender for pigments, enhancing durability without affecting color stability in industrial coatings and formulations. Barium forms alloys with metals like aluminum and for specialized industrial applications. Barium-aluminum alloys improve machinability and deoxidize castings in , while barium- alloys contribute to materials due to enhanced absorption properties. In and ceramics manufacturing, is incorporated into specialty for tubes to absorb X-rays, owing to barium's high and density. Barium , a key compound, is employed in multilayer capacitors, exhibiting a high constant of around 4,000 that enables compact, high-capacitance components for . Barium nitrate is utilized in to produce vibrant green flames in and signal flares, resulting from the excitation of barium ions in the process.

Medical and diagnostic uses

serves as a primary in , particularly for fluoroscopic and radiographic examinations of the gastrointestinal () tract, due to its high and insolubility in , which prevents systemic absorption and minimizes toxicity risks. Administered as a suspension, typically at concentrations of 60% weight/volume (w/v) for upper studies, it coats the mucosal lining to enhance visibility of structures like the , , and during procedures. This non-absorbable property makes it suitable for oral or , with formulations often including suspending agents to maintain uniformity and patient tolerance. The use of barium sulfate in diagnostic imaging originated in the early , with the first clinical applications as a "barium meal" for esophageal and gastric studies emerging around 1906-1910, pioneered by American physiologist Walter and others who recognized its potential to outline GI anatomy under X-rays. By the 1920s, refined suspensions like I-X Barium Meal were commercially available, enabling widespread adoption for evaluating swallowing disorders, ulcers, and obstructions. This historical technique, known as the upper GI series or barium swallow, remains a standard for dynamic assessment of esophageal motility and function. In procedures such as the upper GI series, patients typically ingest 200-500 mL of on an empty , followed by serial imaging in various positions to track its passage through the and . The process, lasting 30-60 minutes, allows real-time to detect abnormalities like strictures or , with post-procedure hydration and laxatives recommended to counteract common side effects such as or impaction from residual barium. These side effects are generally mild and self-limiting, occurring in a minority of cases due to the agent's inert . Beyond imaging, certain barium compounds find limited pharmaceutical applications, primarily in where barium-impregnated spheres (BIPS) serve as an alternative to liquid suspensions for radiographic evaluation of GI transit in small animals. Soluble forms like barium acetate are rarely used in human or veterinary therapeutics owing to their high toxicity potential, including risks of and cardiac arrhythmias, restricting them to niche roles such as laboratory reagents rather than clinical medications. While advancements in cross-sectional imaging have introduced alternatives like computed tomography (CT) with iodinated contrasts or magnetic resonance imaging (MRI) for GI evaluation, barium sulfate retains value for its cost-effectiveness in routine diagnostics, particularly in resource-limited settings where it provides comparable sensitivity for mucosal lesions at a fraction of the expense of iodine-based agents or MRI scans. For instance, barium studies cost significantly less than CT with contrast, making them preferable for initial screening of dysphagia or uncomplicated cases, though CT and MRI are increasingly favored for their multiplanar capabilities and avoidance of radiation in younger patients.

Scientific and environmental uses

Barium plays a specialized role in through the production of cosmogenic isotopes in meteorites. Cosmic rays interacting with barium in meteoritic material generate ¹²⁶Xe via reactions, allowing researchers to calculate exposure ages that reveal the duration meteoroids spent in space before impacting . This method complements other nuclide-based techniques and provides insights into the ejection histories of meteorites from their parent bodies. In , barium vapor lamps serve as precise wavelength standards due to the sharp emission lines of barium ions. The Ba II line at 455.4 nm is particularly valued for calibrating instruments in the , enabling high-resolution measurements in atomic and molecular . These lamps offer stable output for referencing spectra and other short-wavelength transitions, supporting advancements in precision . Barium also enhances catalytic processes in scientific research on synthesis. In variants of the Haber-Bosch process, barium-promoted iron catalysts, often alloyed with and supported on carbon, improve reaction efficiency by modifying electronic properties and structures. This promotion effect facilitates lower-temperature operation and higher yields, informing studies on sustainable . Emerging applications in leverage barium ions for trapped-ion qubits. Barium-137 isotopes, enriched for stability, enable high-fidelity gate operations exceeding 99.9% and programmable entanglement via Rydberg states, addressing scalability challenges in quantum processors. Recent developments, including IonQ's barium-based systems and commercial isotope production, highlight barium's advantages in coherence times and integration with optical systems, marking a post-2020 growth in this field. Environmentally, dissolved barium acts as a conservative tracer for mixing rates and mass circulation. Its nutrient-like distribution, with surface depletions and deep enrichments, reflects biological uptake and remineralization, allowing quantification of vertical and lateral mixing on timescales of years to millennia. Barium isotopes further delineate influences from continental margins and high-latitude inputs. Barite (BaSO₄) precipitation in and its accumulation in marine sediments serve as indicators of productivity. Formed in microenvironments around decaying , barite correlates with particulate organic carbon from surface waters, providing a proxy unaffected by in oxic sediments. This makes it reliable for reconstructing historical carbon cycling in low-oxygen zones. In paleoceanography, Ba/Al ratios in sediment cores proxy nutrient cycling and paleo-productivity over millennia. Excess barium (beyond detrital inputs) signals biogenic barite formation linked to and export, with ratios distinguishing biological from lithogenic sources. This approach reveals past ocean ventilation and intensities, particularly in regions like the .

Health effects

Biological role

Barium has no known essential biological role in humans or other higher organisms, though its allows it to mimic calcium (Ca²⁺) in certain physiological processes, often leading to disruption rather than function. In microorganisms, barium plays a role in processes mediated by certain . Sulfate-reducing bacteria, such as those found in cold sulfur-spring environments, facilitate the precipitation of (barite, BaSO₄) crystals within microbial mats, counteracting oxidation and maintaining dysoxic conditions. Similarly, sulfur-oxidizing bacteria at marine cold seeps promote barite encrustation on bacterial filaments, contributing to barium cycling in sulfidic settings. Plants do not require barium but can accumulate it from soil, particularly in contaminated environments. Members of the family, such as (Indian mustard), act as hyperaccumulators, tolerating and sequestering barium in their tissues under stress conditions. Typical barium concentrations in plants range from 1 to 198 mg kg⁻¹ dry weight, though hyperaccumulators may reach higher levels in barium-rich soils to aid in . In animal physiology, barium occurs at trace levels, substituting for calcium in skeletal structures due to . Human contains approximately 7–10 ppm barium, primarily incorporated during mineralization, while similar substitutions occur in and shells. These low concentrations reflect environmental exposure rather than any functional necessity. Barium's , driven by microbial processes, has influenced in extreme environments. In ancient marine systems, bacterial of barium and mobilization shaped early microbial communities in redox-variable settings, such as hydrothermal vents and anoxic basins, potentially expanding habitable niches over geological time.

Toxicity and safety

Soluble barium salts, such as (BaCl₂), exhibit high acute toxicity primarily through ingestion, leading to severe by blocking efflux channels in cell membranes. This blockade inhibits the inward rectifier current, causing rapid shifts of into cells and resulting in symptoms like gastrointestinal distress, , , and potentially fatal cardiac arrhythmias. The (LD50) for administered orally to rats is 118 mg/kg, highlighting the potency of soluble forms compared to insoluble compounds. Chronic exposure to soluble barium compounds can induce and cardiac arrhythmias due to sustained interference with balance and cardiovascular function. In contrast, insoluble (BaSO₄) is generally considered non-toxic when ingested, as its low limits systemic absorption; however, prolonged inhalation of dust, as in occupational settings, poses a risk of baritosis, a benign form of characterized by radiographic lung opacities without significant functional impairment. Primary exposure routes include inhalation of barite (barium sulfate ore) dust during mining or processing, with the (OSHA) setting permissible exposure limits at 15 mg/m³ for total dust and 5 mg/m³ for the respirable fraction over an 8-hour workday. Ingestion occurs via contaminated , where levels exceeding 2 mg/L— the U.S. Environmental Protection Agency (EPA) maximum contaminant level—may contribute to adverse health effects, while the (WHO) guideline value is 0.7 mg/L based on cardiovascular risks. Dermal absorption is minimal due to barium's poor skin permeability. At the cellular level, the Ba²⁺ ion mimics calcium (Ca²⁺) in signaling pathways, entering cells through voltage-gated calcium channels and disrupting excitation-contraction coupling in muscles, which can lead to from sarcolemmal and calcium overload. This interference exacerbates hypokalemia-induced neuromuscular effects, underscoring the need for prompt intervention in cases. Regulatory frameworks classify soluble barium compounds (excluding ) as Group D—not classifiable as to carcinogenicity—by the EPA due to inadequate evidence from and studies. Acute barium is treated with intravenous supplementation to restore serum levels and oral sodium or to precipitate insoluble in the gut, reducing absorption; supportive measures like may be required for severe cases. Environmentally, barium from runoff can leach into waterways, facilitating in aquatic organisms and subsequent transfer through food chains, potentially elevating concentrations in and consumed by humans.

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