Metalloid
Antimony is a chemical element with the symbol Sb (from Latin stibium) and atomic number 51. A lustrous grey metal or metalloid, it occurs in nature mainly in the form of the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient history and were powdered for use as cosmetics (often known by the Arabic name kohl) and as medicine.
China is the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. The industrial methods for refining antimony from stibnite are roasting followed by reduction with carbon, or direct reduction of stibnite with iron.
The most common applications for metallic antimony are in alloys with lead and tin, which have improved properties for solders, bullets, and plain bearings. It improves the rigidity of lead-alloy plates in lead–acid batteries. Antimony trioxide is a prominent additive for halogen-containing flame retardants. Antimony is used as a dopant in semiconductor devices.
Antimony(III) sulfide, Sb2S3, was recognized in predynastic Egypt as an eye cosmetic (kohl) as early as about 3100 BC, when the cosmetic palette was invented.
An artifact, said to be part of a vase, made of antimony dating to about 3000 BC was found at Telloh, 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. Austen, at a lecture by Herbert Gladstone in 1892, commented 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' (artifact mentioned above) must represent the lost art of rendering antimony malleable."
The British archaeologist Roger Moorey was unconvinced the artifact was indeed a vase, mentioning that Selimkhanov, after his analysis of the Tello 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." This weakens the evidence for a lost art "of rendering antimony malleable".
The Roman scholar Pliny the Elder described several ways of preparing antimony sulfide for medical purposes in his treatise Natural History, around 77 AD. …
Antimony is a member of group 15 of the periodic table. As one of the elements called pnictogens, it has an electronegativity of 2.05. In accordance with periodic trends, it is more electronegative than tin or bismuth, and less electronegative than tellurium or arsenic. As a metalloid, it has a Mohs scale hardness of 3.
Antimony is a silvery, lustrous gray solid that is stable in air at room temperature. If heated, it reacts with oxygen to produce antimony trioxide,Sb2O3. Antimony is attacked by oxidizing acids.
The stable allotrope of antimony crystallises in a trigonal cell, isomorphic with bismuth and the gray allotrope of arsenic.
A yellow allotrope of antimony, assumed to be analogous to yellow arsenic, forms by oxidation of stibine (SbH3) with air or oxygen at −90 °C. At ambient temperatures and in ambient light, it transforms into the more stable black allotrope. A rare explosive form of antimony can be formed from the electrolysis of antimony trichloride, but it always contains appreciable chlorine and is not really an antimony allotrope. When scratched with a sharp implement, an exothermic reaction occurs and white fumes are given off as metallic antimony forms; when rubbed with a pestle in a mortar, a strong detonation occurs.
Elemental antimony adopts a layered structure (space group R3m No. 166) whose layers consist of fused, ruffled, six-membered rings. …
The abundance of antimony in the Earth's crust is estimated at 0.2 parts per million, comparable to thallium at 0.5 ppm and silver at 0.07 ppm. It is the 63rd most abundant element in the crust. Even though this element is not abundant, it is found in more than 100 mineral species. Antimony is sometimes found natively (e.g. on Antimony Peak), but more frequently it is found in the sulfide stibnite (Sb2S3) which is the predominant ore mineral.
In 2017, approximately 48% of antimony was consumed in flame retardants, 33% in lead–acid batteries, and 8% in plastics.
Antimony is mainly used as the trioxide for flame-proofing compounds, always in combination with halogenated flame retardants except in halogen-containing polymers. The flame retarding effect of antimony trioxide is produced by the formation of halogenated antimony compounds, which react with hydrogen atoms, and probably also with oxygen atoms and OH radicals, thus inhibiting fire. Markets for these flame-retardants include children's clothing, toys, aircraft, and automobile seat covers. They are also added to polyester resins in fiberglass composites for such items as light aircraft engine covers. The resin will burn in the presence of an externally generated flame, but will extinguish when the external flame is removed. Antimony trioxide is also used as a synergist with brominated flame retardants in housings and plastic parts for electrical and electronic equipment (e.g., HIPS/ABS enclosures) to meet flammability standards such as UL 94.
Antimony forms a highly useful alloy with lead, increasing its hardness and mechanical strength. When casting it increases fluidity of the melt and reduces shrinkage during cooling. For most applications involving lead, varying amounts of antimony are used as alloying metal. In lead–acid batteries, this addition improves plate strength and charging characteristics. …
Antimony has two stable isotopes: 121Sb with a natural abundance of 57.21% and 123Sb with a natural abundance of 42.79%. There are 37 artificial radioactive isotopes known with mass numbers 104 to 142, of which the longest-lived is the fission product 125Sb with a half-life of 2.758 years. Numerous meta states are known, of which the most stable is 120m1Sb with a half-life of 5.76 days. Isotopes that are lighter than the stable 123Sb tend to undergo β+ decay, and those that are heavier experience β− decay, with some exceptions.
Antimony and many of its compounds are toxic, and the effects of antimony poisoning are similar to arsenic poisoning. The toxicity of antimony is far lower than that of arsenic; this might be caused by the significant differences of uptake, metabolism, and excretion between arsenic and antimony. The uptake of antimony(III) or antimony(V) in the gastrointestinal tract is at most 20%. Antimony(V) is not quantitatively reduced to antimony(III) in the cell (in fact antimony(III) is oxidised to antimony(V) instead).
Since biomethylation of antimony does not occur, the excretion of antimony(V) in urine is the main way of elimination. Like arsenic, the most serious effect of acute antimony poisoning is cardiotoxicity and the resulting myocarditis; however, it can also manifest as Adams–Stokes syndrome, which arsenic does not. Reported cases of intoxication by antimony equivalent to 90 mg antimony potassium tartrate dissolved from enamel has been reported to show only short-term effects. An intoxication with 6 g of antimony potassium tartrate was reported to result in death after three days.
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, or damage the kidneys and the liver, causing violent and frequent vomiting, leading to death in a few days. …