Unlike oxides of phosphorus and arsenic, these oxides are amphoteric, do not form well-defined oxoacids, and react with acids to form antimony salts.ģ is unknown, but the conjugate base sodium antimonite ( [NaĦ. Antimony also forms a mixed-valence oxide, antimony tetroxide ( SbĤ), which features both Sb(III) and Sb(V). Antimony pentoxide ( Sbġ0) can be formed only by oxidation with concentrated nitric acid. In the gas phase, the molecule of the compound is SbĦ, but it polymerizes upon condensing. The +5 oxidation state is more stable.Īntimony trioxide is formed when antimony is burnt in air.
: 758 Isotopes Īntimony compounds are often classified according to their oxidation state: Sb(III) and Sb(V). This relatively close packing leads to a high density of 6.697 g/cm 3, but the weak bonding between the layers leads to the low hardness and brittleness of antimony. The nearest and next-nearest neighbors form an irregular octahedral complex, with the three atoms in each double layer slightly closer than the three atoms in the next. 166) whose layers consist of fused, ruffled, six-membered rings. Įlemental antimony adopts a layered structure ( space group R 3m No. Above this temperature and in ambient light, this metastable allotrope transforms into the more stable black allotrope. The yellow allotrope of antimony is the most unstable it has been generated only by oxidation of stibine (SbH 3) at −90 ☌. At 100 ☌, it gradually transforms into the stable form. It has the same crystal structure as red phosphorus and black arsenic it oxidizes in air and may ignite spontaneously. Black antimony is formed upon rapid cooling of antimony vapor. 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. A rare explosive form of antimony can be formed from the electrolysis of antimony trichloride. When slowly cooled, molten antimony crystallizes into a trigonal cell, isomorphic with the gray allotrope of arsenic. Elemental antimony is a brittle, silver-white, shiny metalloid. Antimony is resistant to attack by acids.įour allotropes of antimony are known: a stable metallic form, and three metastable forms (explosive, black, and yellow).
Coins of antimony were issued in China's Guizhou province in 1931 durability was poor, and minting was soon discontinued. : 758Īntimony is a silvery, lustrous gray metalloid with a Mohs scale hardness of 3, which is too soft to mark hard objects. Antimony is stable in air at room temperature, but reacts with oxygen if heated to produce antimony trioxide, Sb 2O 3. In accordance with periodic trends, it is more electronegative than tin or bismuth, and less electronegative than tellurium or arsenic. Antimony is used as a dopant in semiconductor devices.Ĭrystal structure common to Sb, AsSb and gray AsĪntimony is a member of group 15 of the periodic table, one of the elements called pnictogens, and has an electronegativity of 2.05. Antimony trioxide is a prominent additive for halogen-containing flame retardants. It improves the rigidity of lead-alloy plates in lead–acid batteries. The largest applications for metallic antimony are in alloys with lead and tin, which have improved properties for solders, bullets, and plain bearings. The industrial methods for refining antimony from stibnite are roasting followed by reduction with carbon, or direct reduction of stibnite with iron. The earliest known description of the metal in the West was written in 1540 by Vannoccio Biringuccio.Ĭhina is the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name kohl. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb 2S 3). Antimony is a chemical element with the symbol Sb (from Latin: stibium) and atomic number 51.
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