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Antimony

Antimony

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Antimony (Sb) is a chemical element, a silvery-white, brittle metalloid with atomic number 51. It's known for being a poor conductor of heat and electricity. Antimony is primarily used to harden and strengthen other metals like lead, particularly in batteries. It also finds applications in flame retardants, semiconductors, and various alloys.

Antimony is primarily used to create alloys, flame retardants, and in the glass industry. It's a metalloid, meaning it has properties of both metals and nonmetals, making it useful in various applications.

Summary

Antimony is a chemical element; it has symbol Sb (from Latin stibium) and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name kohl. The earliest known description of this metalloid in the West was written in 1540 by Vannoccio Biringuccio.

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 (Sb) is a chemical element with atomic number 51, belonging to the group 15 (pnictogens) on the periodic table. It's a silvery-white, brittle metalloid, exhibiting metallic and non-metallic properties. Antimony is naturally found as the mineral stibnite (Sb2S3). It's used in alloys to increase hardness, in semiconductors, and as a flame retardant.

Details

antimony (Sb), a metallic element belonging to the nitrogen group (Group 15 [Va] of the periodic table). Antimony exists in many allotropic forms (physically distinct conditions that result from different arrangements of the same atoms in molecules or crystals). Antimony is a lustrous silvery bluish white solid that is very brittle and has a flaky texture. It occurs chiefly as the gray sulfide mineral stibnite (Sb2S3).

Element Properties

atomic number  :  51
atomic weight  :  121.76
melting point  :  630.5 °C (1,166.9 °F)
boiling point  :  1,380 °C (2,516 °F)
density  :  6.691 gram/{cm}^{3} at 20 °C (68 °F)
oxidation states     :  −3, +3, +5

History

The ancients were familiar with antimony both as a metal and in its sulfide form. Fragments of a Chaldean vase made of antimony have been estimated to date to about 4000 bce. Stibnite was used in ancient Egypt as eye makeup. Pliny the Elder, during the 1st century ce, wrote of seven different medicinal remedies using what he called stimi or stibi (stibium), which likely refers to antimony sulfide. Early writings of Dioscorides, dating from about the same time, mention metallic antimony. Records of the 15th century show the use of the substance in alloys for type, bells, and mirrors. In 1615 Andreas Libavius, a German physician, described the preparation of metallic antimony by the direct reduction of the sulfide with iron, and a chemistry textbook published in 1675 by Nicolas Lémery also describes methods of preparation of the element. In the same century, a book summarizing available knowledge of antimony and its compounds was published that had purportedly been written by a Basil Valentine, allegedly a Benedictine monk of the 15th century, whose name appears on chemical writings over a span of two centuries. The name antimony comes from the medieval Latin antimonium, whose origin is uncertain.

Occurrence and distribution

Antimony is about one-fifth as abundant as math, contributing on the average about one gram to every ton of Earth’s crust. Its cosmic abundance is estimated as about one atom to every five million atoms of silicon. Small deposits of native metal have been found, but most antimony occurs in the form of more than a hundred different minerals. The most important of these is stibnite, Sb2S3. Stibnite deposits are found in Algeria, Bolivia, China, Mexico, Peru, South Africa, and parts of the Balkan Peninsula. Some economic value also attaches to kermesite (2Sb2S3 · Sb2O3), argentiferous tetrahedrite [(Cu,Fe)12Sb4S13], livingstonite (HgSb4S7), and jamesonite (Pb4FeSb6S14). As of 2020 about half of the antimony mined in the world came from China, and much of the rest came from Russia and Tajikistan. Small amounts are also recoverable from the production of copper and lead. Some antimony is reclaimed from scrap lead alloy from old batteries, to which antimony had been added to provide hardness.

Two stable isotopes, antimony-121 and antimony-123, nearly equal in abundance, occur in nature. Many radioactive isotopes have been prepared.

Commercial production and uses

High-grade or enriched stibnite reacts directly with scrap iron in the molten state, liberating antimony metal. The metal can also be obtained by conversion of stibnite to the oxide, followed by reduction with carbon. Sodium sulfide solutions are effective leaching agents for the concentration of stibnite from ores. Electrolysis of these solutions produces antimony. After further purification of the crude antimony, the metal, called regulus, is cast into cakes.

About half of this antimony is used metallurgically, principally in alloys. Because some antimony alloys expand on solidifying (a rare characteristic that they share with water), they are particularly valuable as castings and type metal; the expansion of the alloy forces the metal to fill the small crevices of casting molds. Moreover, the presence of antimony in type metal, which also includes lead and small amounts of tin, increases the hardness of the type and gives it a sharp definition. Even when added in minor quantities, antimony imparts strength and hardness to other metals, particularly lead, with which it forms alloys used in plates of automobile storage batteries, in bullets, in coverings for cables, and in chemical equipment such as tanks, pipes, and pumps. Combined with tin and lead, antimony forms antifriction alloys called babbitt metals, which are used as components of machine bearings. With tin, antimony forms such alloys as britannia metal and pewter, used for utensils. Antimony is also used as an alloy in solder. Highly purified antimony is used in semiconductor technology to prepare the intermetallic compounds indium, aluminum, and gallium antimonide for diodes and infrared detectors.

Antimony compounds (especially the trioxide) are widely used as flame retardants in paints, plastics, rubber, and textiles. Several other antimony compounds are used as paint pigments, and tartar emetic (an organic salt of antimony) is used in the textile industry to aid in binding certain dyes to fabrics and in medicine as an expectorant and a nauseant.

Properties and reactions

The most stable form of elemental antimony is a brittle silvery solid of high metallic luster. Electrolytic deposition of antimony under certain conditions produces an unstable amorphous form called “explosive antimony,” because, when bent or scratched, it will change in a mildly explosive manner to the more stable metallic form. There is also an amorphous black form of antimony that results from sudden quenching of the vapor, and a yellow form is produced by low-temperature oxidation of stibine, SbH3, with air or chlorine. Metallic antimony is not affected by air or moisture under ordinary conditions, but it is gradually converted to an oxide if the air is moist. Antimony can be oxidized easily by sulfur and the halogens when heated. When it is heated in air, it burns with a brilliant blue flame and gives off white fumes of the trioxide Sb2O3. The trioxide of antimony is soluble in either acids or alkalies.

The electronic structure of antimony closely resembles that of math, having three half-filled orbitals in the outermost shell. Thus, it can form three covalent bonds and exhibit +3 and −3 oxidation states. The electronegativity of antimony is lower than that of math. It can act as an oxidizing agent and reacts with many metals to form antimonides that, in general, resemble nitrides, phosphides, and math but are somewhat more metallic. The promotion of one of the lone-pair electrons to an outer d orbital apparently occurs more easily with antimony than with math, since antimony exhibits the +5 oxidation state in forming both the pentafluoride and the pentachloride.

Analytical chemistry

Antimony may be separated and weighed for analysis as the sulfide, Sb2S3. Alternatively, the sulfide may be converted to the oxide and, after careful ignition, weighed as Sb4O6. Numerous volumetric methods are also available, including several methods of oxidizing antimony in the +3 oxidation state with potassium permanganate, potassium bromate, or iodine. In the absence of math, small amounts of antimony may be determined by a modified Gutzeit method.

Biological and physiological significance

Antimony and a number of its compounds are highly toxic. In fact, the use of antimony compounds for medicinal purposes was temporarily outlawed several centuries ago because of the number of fatalities they had caused. A hydrated potassium antimonyl tartrate called “tartar emetic” is currently used in medicine as an expectorant, diaphoretic, and emetic. The maximum tolerable concentration of antimony dust in air is about 0.5 milligram per cubic meter.

Additional Information:

Appearance

Antimony is a semi-metal. In its metallic form it is silvery, hard and brittle.

Uses

Antimony is used in the electronics industry to make some semiconductor devices, such as infrared detectors and diodes.

It is alloyed with lead or other metals to improve their hardness and strength. A lead-antimony alloy is used in batteries. Other uses of antimony alloys include type metal (in printing presses), bullets and cable sheathing.

Antimony compounds are used to make flame-retardant materials, paints, enamels, glass and pottery.

Biological role

Antimony and many of its compounds are toxic.

Natural abundance

Antimony is not an abundant element but is found in small quantities in over 100 mineral species. It is most often found as antimony(III) sulfide. It is extracted by roasting the antimony(III) sulfide to the oxide, and then reducing with carbon. Antimony can also be found as the native metal.

China produces 88% of the world’s antimony. Other producers are Bolivia, Russia and Tajikistan.

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