Antimony

tin ← antimony → tellurium As ↑ Sb ↓ Bi 51Sb Periodic table
Appearance
silvery lustrous gray
General properties
Name, symbol, number	antimony, Sb, 51
Pronunciation	/ˈæntɨmɵnɪ/ an-ti-mo-nee[note 1]
Element category	metalloid
Group, period, block	15, 5, p
Standard atomic weight	121.760(1)
Electron configuration	[Kr] 4d10 5s2 5p3
Electrons per shell	2, 8, 18, 18, 5 (Image)
Physical properties
Phase	solid
Density (near r.t.)	6.697 g·cm−3
Liquid density at m.p.	6.53 g·cm−3
Melting point	903.78 K, 630.63 °C, 1167.13 °F
Boiling point	1860 K, 1587 °C, 2889 °F
Heat of fusion	19.79 kJ·mol−1
Heat of vaporization	193.43 kJ·mol−1
Molar heat capacity	25.23 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 807 876 1011 1219 1491 1858
Atomic properties
Oxidation states	5, 3, -3
Electronegativity	2.05 (Pauling scale)
Ionization energies (more)	1st: 834 kJ·mol−1
	2nd: 1594.9 kJ·mol−1
	3rd: 2440 kJ·mol−1
Atomic radius	140 pm
Covalent radius	139±5 pm
Van der Waals radius	206 pm
Miscellanea
Crystal structure	trigonal
Magnetic ordering	diamagnetic[1]
Electrical resistivity	(20 °C) 417 nΩ·m
Thermal conductivity	24.4 W·m−1·K−1
Thermal expansion	(25 °C) 11 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 3420 m·s−1
Young's modulus	55 GPa
Shear modulus	20 GPa
Bulk modulus	42 GPa
Mohs hardness	3.0
Brinell hardness	294 MPa
CAS registry number	7440-36-0
Most stable isotopes
Main article: Isotopes of antimony
iso NA half-life DM DE (MeV) DP 121Sb 57.36% 121Sb is stable with 70 neutrons 123Sb 42.64% 123Sb is stable with 72 neutrons 125Sb syn 2.7582 y β− 0.767 125Te
· r

Antimony ( /ænˈtɪmɵni/ an-ti-mo-nee or  /ˈæntəˌmoʊni/ an-tə-moh-nee;^{[note 2]} Latin: stibium) is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb₂S₃). Although the use of antimony is limited by its toxicity, its compounds have been of fundamental value in chemistry – a prominent example being the development of superacids derived from antimony pentafluoride.^[2] Antimony compounds are prominent fire retardants found in many commercial and domestic products. Certain alloys are valuable for use in solders and ball bearings. An emerging application is the use of antimony in microelectronics.

Contents 1 History 1.1 Etymology 2 Characteristics 2.1 Properties 2.2 Isotopes 2.3 Occurrence 3 Production 4 Compounds 4.1 Oxides and hydroxides 4.2 Halides 4.3 Antimonides, hydrides, and organoantimony compounds 5 Applications 5.1 Flame retardants 5.2 Alloys 5.3 Other applications 5.4 Niche applications 5.4.1 Microelectronics 5.4.2 Medical 5.4.3 Other uses 6 Precautions 7 See also 8 Notes 9 References 10 Bibliography 11 External links

History

Antimony's sulfide compound, antimony(III) sulfide, Sb₂S₃ was recognized in antiquity, at least as early as 3000 BC.

An artifact, said to be part of a vase, made of antimony dating to about 3000 BC was found at Tello, Chaldea (part of present-day Iraq), and a copper object plated with antimony dating between 2500 BC and 2200 BC has been found in Egypt.^[3] One contemporary (Austen, at a lecture by Herbert Gladstone, published in 1892) was reported^[4] to comment that "we only know of antimony at the present day as a highly brittle and crystalline metal, which could hardly be fashioned into a useful vase, and therefore this remarkable 'find' must represent the lost art of rendering antimony malleable."^[4] However, Moorey was unconvinced that the artefact was indeed a vase, mentioning that Selimkhanov, after his analysis of the Telloh object (published in 1975), "attempted to relate the metal to Transcaucasian natural antimony" (i.e. native metal) and that "the antimony objects from Transcaucasia are all small personal ornaments."^[4] This weakens the evidence for a lost art "of rendering antimony malleable."

The first European description of a procedure for isolating antimony is in the book De la pirotechnia of 1540 by Vannoccio Biringuccio. This book predates the more famous 1556 book by Agricola, De re metallica, even though Agricola has been often incorrectly credited with the discovery of metallic antimony. A text describing the preparation of metallic antimony that was published in Germany in 1604 purported to date from the early fifteenth century, and if authentic it would predate Biringuccio. The book, written in Latin, was called "Currus Triumphalis Antimonii" (The Triumphal Chariot of Antimony), and its putative author was a certain Benedictine monk, writing under the name Basilius Valentinus.^[5][6] An English translation of the "Currus Triumphalis" appeared in English in 1660, under the title The Triumphant Chariot of Antimony. The work remains of great interest, chiefly because it documents how followers of the renegade German physician, Philippus Theophrastus Paracelsus von Hohenheim (of whom Thölde was one), came to associate the practice of alchemy with the preparation of chemical medicines.

Pure antimony was well known to Jābir ibn Hayyān, sometimes called "the Father of Chemistry", in the 8th century. Here there is still an open controversy: Marcellin Berthelot, who translated a number of Jābir's books, stated that antimony is never mentioned in them, but other authors^[7] claim that Berthelot translated only some of the less important books, while the more interesting ones (some of which might describe antimony) are not yet translated, and their content is completely unknown.

The first natural occurrence of pure antimony ('native antimony') in the Earth's crust was described by the Swedish scientist and local mine district engineer Anton von Swab in 1783. The type-sample was collected from the Sala Silver Mine in the Bergslagen mining district of Sala, Västmanland, Sweden.^[8]

Etymology

The ancient words for antimony mostly have, as their chief meaning, kohl, the sulfide of antimony. Pliny the Elder, however, distinguishes between male and female forms of antimony; his male form is probably the sulfide, while the female form, which is superior, heavier, and less friable, is probably native metallic antimony.^[9]

The Egyptians called antimony mśdmt; in hieroglyphs, the vowels are uncertain, but there is an Arabic tradition that the word is ميسديميت mesdemet.^[10][11] The Greek word, στίμμι stimmi, is probably a loan word from Arabic or Egyptian sdm , and is used by the Attic tragic poets of the 5th century BC; later Greeks also used στἰβι stibi, as did Celsus and Pliny, writing in Latin, in the first century AD. Pliny also gives the names stimi [sic], larbaris, alabaster, and the "very common" platyophthalmos, "wide-eye" (from the effect of the cosmetic). Later Latin authors adapted the word to Latin as stibium. The Arabic word for the substance, as opposed to the cosmetic, can appear as تحميض، ثمود، وثمود، وثمود ithmid, athmoud, othmod, or uthmod. Littré suggests the first form, which is the earliest, derives from stimmida, (one) accusative for stimmi.^[12]

The use of Sb as the standard chemical symbol for antimony is due to the 18th century chemical pioneer, Jöns Jakob Berzelius, who used this abbreviation of the name stibium.^[13] The medieval Latin form, from which the modern languages and late Byzantine Greek, take their names, is antimonium. The origin of this is uncertain; all suggestions have some difficulty either of form or interpretation. The popular etymology, from ἀντίμοναχός anti-monachos or French antimoine, still has adherents; this would mean "monk-killer", and is explained by many early alchemists being monks, and antimony being poisonous.^{[note 3]} So does the hypothetical Greek word ἀντίμόνος antimonos, "against one", explained as "not found as metal", or "not found unalloyed".^[3][14] Lippmann conjectured a Greek word, ανθήμόνιον anthemonion, which would mean "floret", and he cites several examples of related Greek words (but not that one) which describe chemical or biological efflorescence.^[15]

The early uses of antimonium include the translations, in 1050–1100, by Constantine the African of Arabic medical treatises.^[16] Several authorities believe that antimonium is a scribal corruption of some Arabic form; Meyerhof derives it from ithmid;^[17] other possibilities include Athimar, the Arabic name of the metal, and a hypothetical as-stimmi, derived from or parallel to the Greek.^[18]

Characteristics

Properties

Antimony is in the nitrogen group (group 15) and has an electronegativity of 2.05. As expected by periodic trends, it is more electronegative than tin or bismuth, and less electronegative than tellurium or arsenic.

Antimony is stable in air at room temperature but reacts with oxygen if heated to form antimony trioxide, Sb₂O₃.

Antimony is a silvery, lustrous gray metal that has a Mohs scale hardness of 3. Therefore, antimony by itself is not used to make hard objects: coins made of antimony were issued in China's Guizhou province in 1931, but because of their rapid wear their minting was discontinued.^[19] Antimony is resistant to attack by acids.

Four allotropes of antimony are known: a stable metallic form, and three metastable forms: explosive, black and yellow. Metallic antimony is a brittle, silver-white shiny metal. When molten antimony is slowly cooled, metallic antimony crystallizes in an hexagonal cell, isomorphic with that of the grey allotrope of arsenic. A rare explosive form of antimony can be formed from the electrolysis of antimony(III) trichloride. When scratched with a sharp implement, an exothermic reaction occurs and white fumes given off as metallic antimony is formed; alternatively, when rubbed with a pestle in a mortar, a strong detonation occurs. Black antimony is formed upon rapid cooling of gaseous metallic antimony. It has the same crystal structure as red phosphorus and black arsenic, it oxidizes in air and may ignite spontaneously. At 100 °C, it gradually transforms into the stable form. The yellow allotrope of antimony is the most unstable. It has only been generated by oxidation of stibine (SbH₃) at −90 °C. Above this temperature and in ambient light, this meta stable allotrope transforms into the more stable black allotrope.^[20]

Metallic antimony adopts a double-layered structure (space group R3m No. 166) consisting of many interlocked ruffled six-membered rings. Nearest and next-nearest neighbors form a distorted octahedral complex, with the three atoms in the same double-layer being slightly closer than the three atoms in the next. This relatively close packing leads to a high density of 6.697 g/cm³ whereas the low hardness and brittleness of antimony originate from the weak bonding among the layers.^[21]:758

Isotopes

Antimony exists as two stable isotopes, ¹²¹Sb with a natural abundance of 57.36% and ¹²³Sb with a natural abundance of 42.64%. It also has 35 radioisotopes, of which the longest-lived is ¹²⁵Sb with a half-life of 2.75 years. In addition, 29 metastable states have been characterised.

Occurrence

The abundance of antimony in the Earth's crust is estimated at 0.2 to 0.5 parts per million, comparable to thallium at 0.5 parts per million and silver at 0.07 ppm.^[22] Even though this element is not abundant, it is found in over 100 mineral species. Antimony is sometimes found native, but more frequently it is found in the sulfide stibnite (Sb₂S₃) which is the predominant ore mineral. Commercial forms of antimony are generally ingots, broken pieces, granules, and cast cake. Other forms are powder, shot, and single crystals.

In 2005, the People's Republic of China was the top producer of antimony with about 84% world share followed at a distance by South Africa, Bolivia and Tajikistan, reports the British Geological Survey. The mine with the largest deposits in China is Xikuangshan Mine in Hunan province with a estimated deposit of 2.1 million metric tons.^[23] In October 2011 a deposit of antimony was found in a shallow seabed about 50 km off Amami-Oshima Island in Kagoshima Prefecture. The discovery was the first time that antimony had been found at such shallow depths(480 meters), with this type of mineral deposit only ever having been found in depths in excess of 1000 meters.^[24]

Production

The extraction of antimony from ores depends on the quality of the ore, which is usually a sulfide. The sulfide is converted to an oxide and advantage is often taken of the volatility of antimony(III) oxide, which is recovered from roasting.^[2] This material is often used directly for the main applications, impurities being arsenic and sulfide. Antimony can be isolated from its ore by a reduction with scrap iron:

Sb₂S₃ + 3 Fe → 2 Sb + 3 FeS

Isolating antimony from its oxide is performed by a carbothermal reduction:^[25]

2 Sb₂O₃ + 3 C → 4 Sb + 3 CO₂

Antimony production in 2010^[22]

Country	Tonnes	% of total
People's Republic of China	120,000	88.9
South Africa	3,000	2.2
Bolivia	3,000	2.2
Russia	3,000	2.2
Tajikistan	2,000	1.5
Top 5	131,000	97.0
Total world	135,000	100.0

Compounds

Antimony compounds are often classified into those of Sb(III) and Sb(V).^[26] Relative to its neighboring element As, the 5+ oxidaton state is more stable.

Oxides and hydroxides

Antimony trioxide (Sb₄O₆) is formed when antimony is burnt in air.^[27] In the gas phase, this compound exists as Sb₄O₆, but it polymerises upon condensing.^[21] Antimony pentoxide, (Sb₄O₁₀) can only be formed by oxidation by concentrated nitric acid.^[28] Antimony also forms a mixed-valence oxide, antimony tetroxide (Sb₂O₄), which features both Sb(III) and Sb(V).^[28] Unlike phosphorus and arsenic, these various oxides are amphoteric and do not form well-defined oxoacids and react with acids to form antimony salts.

Antimonous acid Sb(OH)₃ is unknown but the conjugate base sodium antimonite ([Na₃SbO₃]₄) forms upon fusing sodium oxide and Sb₄O₆.^[21]:763 Transition metal antimonites are also known.^[29]:122 Antimonic acid exists only as the hydrate HSb(OH)₆, forming salts containing the antimonate anion Sb(OH)−
6. Dehydrating metal salts containing this anion yields mixed oxides.^[29]:143

Many antimony ores are sulfides, including stibnite (Sb₂S₃), pyrargyrite (Ag₃SbS₃), zinkenite, jamesonite, and boulangerite.^[21]:757 Antimony pentasulfide is non-stoichiometric and features antimony in the +3 oxidation state and S-S bonds.^[30] Several thioantimonides are known such as [Sb₆S₁₀]²⁻ and [Sb₈S₁₃]²⁻.^[31]

Halides

Antimony forms two series of halides, SbX₃ and SbX₅. The trihalides SbF₃, SbCl₃, SbBr₃, and SbI₃ are all molecular compounds having trigonal pyramidal molecular geometry. The trifluoride SbF₃ is prepared by the reaction of Sb₂O₃ with HF:^{[21]:761–762}

Sb₂O₃ + 6 HF → 2 SbF₃ + 3 H₂O

It is Lewis acidic and readily accepts fluoride ions to form the complex anions SbF−
4 and SbF2−
5. Molten SbF₃ is a weak electrical conductor. The trichloride SbCl₃ is prepared by dissolving Sb₂S₃ in hydrochloric acid:

Sb₂S₃ + 6 HCl → 2 SbCl₃ + 3 H₂S

The pentahalides SbF₅ and SbCl₅ have trigonal bipyramidal molecular geometry in the gas phase, but in the liquid phase, SbF₅ is polymeric, whereas SbCl₅ is monomeric.^[21]:761 SbF₅ is a powerful Lewis acid used to make the superacid fluoroantimonic acid ("HSbF₆").

Oxyhalides are more common for antimony than arsenic and phosphorus. Antimony trioxide dissolves in concentrated acid to form antimony oxo- (antimonyl) compounds such as SbOCl and (SbO)₂SO₄.^[21]:764

Antimonides, hydrides, and organoantimony compounds

Compounds in this class generally are described as derivatives of Sb^3-. Antimony forms antimonides with metals, such as indium antimonide (InSb), and silver antimonide (Ag₃Sb).^[21]:760 The alkali metal and zinc antimonides, e.g. Na₃Sb and Zn₃Sb₂, are more reactive. Treating these antimonides with acid produces the unstable gas stibine, SbH₃:^[32]

Sb³⁻ + 3 H⁺ → SbH₃

Stibine can also be produced by treating Sb³⁺ salts with hydride reagents such as sodium borohydride. Stibine decomposes spontaneously at room temperature. Because stibine is thermodynamically unstable (positive heat of formation), antimony does not react with hydrogen directly.^[26]

Organoantimony compounds are typically prepared by alkylation of antimony halides with Grignard reagents.^[33] A large variety of compounds are known with both Sb(III) and Sb(V) centers including mixed chloro-organic derivatives, anions, and cations. Examples include Sb(C₆H₅)₃ (triphenylstibine), Sb₂(C₆H₅)₄ (with an Sb-Sb bond), and cyclic [Sb(C₆H₅)]_n. Pentacoordinated organoantimony compounds are common, examples being Sb(C₆H₅)₅ and several related halides.

Applications

Flame retardants

The main use of antimony is in the form of antimony trioxide is used in the making of flame-proofing compounds. Markets for these flame-retardant applications include children's clothing, toys, aircraft and automobile seat covers. It is also used in the fiberglass composites industry as an additive to polyester resins for such items as light aircraft engine covers. The resin will burn while a flame is held to it but will extinguish itself as soon as the flame is removed. Fireproofing consumes about half of the annual production of antimony.^[2]

Alloys

Antimony forms a highly useful alloy with lead, increasing its hardness and mechanical strength. The Sb–Pb alloy is used in lead–acid batteries.^[2][34] It is used in antifriction alloys, such as Babbitt metal.^[35] It is used as an alloy in bullets and lead shot, cable sheathing, type metal (e.g. for linotype printing machines^[36]), solder – some "lead-free" solders contain 5% Sb,^[37] in pewter,^[38] and in hardening alloys with low tin content in the manufacturing of organ pipes.

Other applications

The second main application is as a catalyst for the production of the polymer polyethyleneterephthalate. It is an additive in some glasses. In the latter application, antimony oxides serve as fining agents, aiding in the removal of microscopic bubbles. This application is mainly used for TV screens.^[39]

Niche applications

Microelectronics

In tiny amounts, antimony is increasingly being used in the semiconductor industry as a dopant for ultra-high conductivity n-type silicon wafers^[40] in the production of diodes, infrared detectors, and Hall-effect devices.

In the 1950s, tiny beads of a lead-antimony alloy were used to dope the emitters and collectors of NPN alloy junction transistors with antimony.^[41]

Medical

Few biological or medical applications exist for antimony. Treatments principally containing antimony are known as antimonials and are used as emetics.

Antimony compounds are used as antiprotozoan drugs. Antimony potassium tartrate, or tartar emetic, was once used as an anti-schistosomal drug, subsequently replaced by praziquantel.

Antimony and its compounds are used in several veterinary preparations like anthiomaline or lithium antimony thiomalate, which is used as a skin conditioner in ruminants.

Antimony has a nourishing or conditioning effect on keratinized tissues, at least in animals. Antimony-based drugs, such as meglumine antimoniate, are also considered the drugs of choice for treatment of leishmaniasis in domestic animals. Unfortunately, as well as having low therapeutic indices, the drugs are poor at penetrating the bone marrow, where some of the Leishmania amastigotes reside, and so cure of the disease – especially the visceral form – is very difficult.

Elemental antimony as an antimony pill was once used as a medicine. It could be reused by others after ingestion.

Other uses

In the heads of some safety matches ^[42] and in nuclear reactors together with beryllium as startup neutron sources.

Antimony sulfides have been shown to help stabilize the friction coefficient in automotive brake pad materials.^[43] Antimony also is used in the making of bullets and bullet tracers. This element is also used in cosmetics and event paint and glass art crafts.

Precautions

Antimony and many of its compounds are toxic, and the effects of antimony poisoning are similar to arsenic poisoning. Inhalation of antimony dust is harmful and in certain cases may be fatal; in small doses, antimony causes headaches, dizziness, and depression. Larger doses such as prolonged skin contact may cause dermatitis; otherwise it can damage the kidneys and the liver, causing violent and frequent vomiting, and will lead to death in a few days.

Antimony is incompatible with strong oxidizing agents, strong acids, halogen acids, chlorine, or fluorine. It should be kept away from heat.^[44]

Antimony leaches from polyethylene terephthalate (PET) bottles into liquids.^[45] While levels observed for bottled water are below drinking water guidelines,^[46] fruit juice concentrates (for which no guidelines are established) produced in the UK were found to contain up to 44.7 µg/L of antimony, well above the EU limits for tap water of 5 µg/L.^[47][48] The guidelines are:

• World Health Organization: 20 µg/L
• Japan: 15 µg/L^[49]
• United States Environmental Protection Agency, Health Canada and the Ontario Ministry of Environment: 6 µg/L
• German Federal Ministry of Environment: 5 µg/L^[46]

See also

	Book: Antimony
Wikipedia books are collections of articles that can be downloaded or ordered in print.

• Antimonial
• Antimony pill
• Phase change memory
• Naturalis Historia
• Pliny the Elder

Notes

References

Bibliography

• Endlich, F.M. (1888). "On Some Interesting Derivations of Mineral Names". The American Naturalist 22 (253): 21–32. doi:10.1086/274630. JSTOR 2451020. 
• Edmund Oscar von Lippmann (1919) Entstehung und Ausbreitung der Alchemie, teil 1. Berlin: Julius Springer (in German).
• Public Health Statement for Antimony

External links

• National Pollutant Inventory – Antimony and compounds
• WebElements.com – Antimony
• Chemistry in its element podcast (MP3) from the Royal Society of Chemistry's Chemistry World: Antimony

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Large version

Antimony compounds SbBr3 Sb(C2H3O2)3 SbCl3 SbCl5 SbF3 SbF5 SbH3 SbI3 Sb2O3 Sb2O4 Sb2O5 Sb2S5 Sb2Se3