antimony

—antimonial, adj., n.

/an"teuh moh'nee/, n. Chem.

a brittle, lustrous, white metallic element occurring in nature free or combined, used chiefly in alloys and in compounds in medicine. Symbol: Sb; at. no.: 51; at. wt.: 121.75.

[1375-1425; late ME antimonie < ML antimonium, perh. < dial. Ar uthmud]

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Semimetallic to metallic chemical element (see metal), chemical symbol Sb, atomic number 51.

Of its various allotropes, the most common is a lustrous, bluish, brittle, flaky solid. In nature antimony occurs chiefly as the gray sulfide mineral stibnite, Sb₂S₃. Pure antimony metal has no important uses, but its alloys and compounds are extremely useful. Some antimony alloys have the rare quality of expanding on solidifying; these are used for castings and for type metal. Alloys with lead are used in car batteries, bullets, and cable sheaths. Antifriction alloys with tin and lead (babbitt metals) are used as components of machine bearings. Antimony compounds (valences 3, 4, and 5) are widely used as flame retardants in paints, plastics, rubber, and textiles; others are used as paint pigments.

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▪ chemical element

  a metallic element belonging to the nitrogen family (Group 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). One method of obtaining antimony from stibnite is by roasting the ore to form the oxide Sb₂O₃, which is then reduced to the element by heating it with carbon. Another is to melt the ore with scrap iron in a furnace; as the iron combines with the sulfur to form a liquid layer of molten iron sulfide, the heavier liquid antimony settles to the bottom and is drawn off.

      Because it is a poor conductor of heat and electricity, antimony tarnishes only slightly in dry air, but it is gradually converted to an oxide if the air is moist. 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.

      In its pure state antimony has no important uses, but, when combined physically or chemically with other substances, it is an extremely useful metal. 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 (lead processing), with which it forms alloys used in plates of automobile storage batteries, in bullets, and in coverings for cables. Combined with tin and lead, antimony forms antifriction alloys called babbitt metals (babbitt metal) that are used as components of machine bearings.

      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; 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.

atomic number

51

atomic weight

121.75

melting point

630.5 °C (1,166.9 °F)

boiling point

1,380 °C (2,516 °F)

density

6.691 g/cm³ at 20 °C (68 °F)

oxidation states

−3, +3, +5

electron config.

1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰5s²5p³

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