Antimony

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Antimony (IPA: (North America) 'æntəməʊni (British English) 'æntəməni) is a chemical element in the periodic table that has the symbol Sb (Latin: stibium, meaning "mark") and atomic number 51. A metalloid, antimony has four allotropic forms. The stable form of antimony is a blue-white metalloid. Yellow and black antimony are unstable non-metals. Antimony is used in flame-proofing, paints, ceramics, enamels, a wide variety of alloys, electronics, and rubber.

[edit] Notable characteristics

Antimony in its elemental form is a silvery white, brittle, fusible, crystalline solid that exhibits poor electrical and heat conductivity properties and vaporizes at low temperatures. A metalloid, antimony resembles a metal in its appearance and in many of its physical properties, but does not chemically react as a metal. It is also attacked by oxidizing acids and halogens. Antimony and some of its alloys are unusual in that they expand on cooling. According to New Scientist (26 May 2007) the earth has an estimated thirty years supply left of this element.

Estimates of the abundance of antimony in the Earth's crust range from 0.2 to 0.5 ppm. Antimony is geochemically categorized as a chalcophile, occurring with sulfur and the heavy metals lead, copper, and silver.

[edit] Applications

Antimony is increasingly being used in the semiconductor industry in the production of diodes, infrared detectors, and Hall-effect devices. As an alloy, this metalloid greatly increases lead's hardness and mechanical strength. The most important use of antimony is as a hardener in lead for storage batteries. Uses include:

• Batteries
• antifriction alloys
• type metal
• small arms and tracer ammunition
• cable sheathing
• matches
• medicines, antiprotozoan drugs
• plumbing
• soldering - some "lead-free" solders contain 5% Sb
• main and big-end bearings in internal combustion engines (as alloy)
• used in the past to treat Schistosomiasis; today Praziquantel is universally used
• used in linotype printing machines

Antimony compounds in the form of oxides, sulfides, sodium antimonate, and antimony trichloride are used in the making of flame-proofing compounds, ceramic enamels, glass, paints, and pottery. Antimony trioxide is the most important of the antimony compounds and is primarily used in flame-retardant formulations. These flame-retardant applications include such markets as children's clothing, toys, aircraft and automobile seat covers. Also, antimony sulfide is one of the ingredients of safety matches.

The natural sulfide of antimony, stibnite, was known and used in Biblical times as medicine and as a cosmetic. Stibnite is still used in some developing countries as medicine. Antimony has been used for the treatment of schistosomiasis. Antimony attaches itself to sulfur atoms in certain enzymes which are used by both the parasite and human host. Small doses can kill the parasite without causing damage to the patient. 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. Tartar emetic is another antimony preparation which is used as an anti-schistosomal drug. Treatments chiefly involving antimony have been called antimonials.

A coin made of antimony was issued in the Keichow Province of China in 1931. The coins were not popular, being too soft and they wore quickly when in circulation. After the first issue no others were produced.^[1]

[edit] Names of antimony

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, the female form, which is superior, heavier, and less friable, is probably native metallic antimony.^[2]

The Egyptians called antimony mśdmt; in hieroglyphics, the vowels are uncertain, but there is an Arabic tradition that the word is mesdemet.^[3] The Greek word, stimmi, is probably a loan word from Arabic or Egyptian, and is used by the Attic tragic poets of the 5th century BC; later Greeks also used 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 ithmid, athmoud, othmod, or uthmod. Littré suggests the first form, which is the earliest, derives from stimmida, (one) accusative for stimmi.^[4]

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.

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 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.^[5] So does the hypothetical Greek word antimonos, "against one", explained as "not found as metal", or "not found unalloyed".^[6] Lippmann conjectured a Greek word, anthemonion, which would mean "floret", and he cites several examples of related Greek words (but not that one) which describe chemical or biological efflorescence.^[7]

The early uses of antimonium include the translations, in 1050-1100, by Constantine the African of Arabic medical treatises.^[8] Several authorities believe that antimonium is a scribal corruption of some Arabic form; Meyerhof derives it from ithmid;^[9] other possibilities include Athimar, the Arabic name of the metal, and a hypothetical *as-stimmi, derived from or parallel to, the Greek.^[10]

[edit] History

Antimony's sulfide compound, antimony (III) trisulfide, Sb₂S₃ was recognized in antiquity, at least as early as 3000 BC. Pastes of Sb₂S₃ powder in fat^[11] or in other materials have been used since that date as eye cosmetics in the Middle East and farther afield; in this use, Sb₂S₃ is called "kohl". It was used to darken the brows and lashes, or to draw a line around the perimeter of the eye.

An artifact 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.^[12] There is some uncertainty as to the description of the artifact from Tello. Although it is sometimes reported to be a vase, a recent detailed discussion of it reports it to be rather a fragment of indeterminate purpose.^[13]

According to the history of metallurgy, the first description of a procedure for isolating antimony is in the book De la pirotechnia of 1540 by Vannoccio Biringuccio, written in Italian. This book precedes the more famous 1556 book in Latin by Agricola, De re metallica, even though Agricola has been often incorrectly credited with the discovery of metallic antimony.

According to the traditional history of western alchemy, metallic antimony was described (previous to Biringuccio) by the putative Prior Basilius Valentinus in a Latin manuscript, Currus Triumphalis Antimonii, supposedly circa 1450. This manuscript was published in 1604 in English translation as The Triumphal Chariot of Antimony, by Johann Thölde (1565–1614). The marvelous discovery of a complete set of Valentinus' manuscripts, including the alchemical tales, is fully described by Jean-Jacques Manget in his Bibliotheca chemica curiosa (1702): the manuscripts had been enclosed for more than a century in a pillar of St. Peter's Abbey, at Erfurt, until the pillar was shattered by a thunderbolt. Many scholars have considered Basilius Valentinus a mythological personage. Gottfried Wilhelm Leibniz (1646–1716) declared, after careful enquiry, that no Prior Valentinus ever existed in the Abbey of Erfurt, rather that the name was only a pseudonym – probably of Thölde himself – used to merge poorly translated materials of various origins.

According to the traditional history of Middle Eastern alchemy, pure antimony was well known to Geber, sometimes called "the Father of Chemistry", in the 8th century. Here there is still an open controversy: Marcellin Berthelot, who translated a number of Geber's books, stated that antimony is never mentioned in them, but other authors 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.

[edit] Sources

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, 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.

Chiffres de 2003, métal contenue dans les minerais et concentrés, source : L'état du monde 2005

The largest mine in China is Xikuangshan mine in Hunan Province.

See also Antimonide minerals, Antimonate minerals.

[edit] Precautions

Antimony and many of its compounds are toxic. Clinically, antimony poisoning is very similar to arsenic poisoning. In small doses, antimony causes headache, dizziness, and depression. Larger doses cause violent and frequent vomiting, and will lead to death in a few days.

See also arsenic poisoning.

[edit] Leaching from PET

A study found that antimony is leaching from PET bottles (reported for some acidic fruit drinks),^{[citation needed]} but at levels below drinking water guidelines. The guidelines are:

• WHO, 20 µg l^–1
• Japan, 15 µg l^–1[14]
• US EPA, Health Canada and the Ontario Ministry of Environment, 6 µg l^–1
• German Federal Ministry of Environment, 5 µg l^–1[15]

The acidic nature of the drink is sufficient to dissolve small amounts of antimony oxide contained in the packaging of the drink;^{[citation needed]} modern manufacturing methods prevent this occurrence.^{[citation needed]} However, researchers are concerned that antimony levels correspond to duration the bottle is left to stand - the longer the beverage has been bottled, the higher the antimony leached.^{[citation needed]}

[edit] Compounds

• Antimony pentafluoride SbF₅
• Antimony trioxide Sb₂O₃
• Stibine (antimony trihydride SbH₃)
• Indium antimonide (InSb)

See also Antimony compounds.