General Information

Sb, from Latin stibium), 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, 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 that are used as components of machine bearings.

Occurrence, uses, and properties.

Antimony is about one-fifth as abundant as arsenic, contributing on the average about one gram to every ton of the Earth's crust. Its cosmic abundance is estimated as about one atom to every 5,000,000 atoms of silicon. Small deposits of native metal have been found, but most antimony occurs in the form of more than 100 different minerals. The most important of these is stibnite, Sb2S3. Small stibnite deposits are found in Algeria, Bolivia, China, Mexico, Peru, South Africa, and in parts of the Balkan Peninsula. Some economic value also attaches to kermesite (2Sb2S3 Sb2O3), argentiferous tetrahedrite [(Cu,Fe)12Sb4S13], livingstonite (HgSb4S7), and jamesonite (Pb4FeSb6S14). Small amounts are also recoverable from the production of copper and lead. About half of all the antimony produced is reclaimed from scrap lead alloy from old batteries, to which antimony had been added to provide hardness.

History

Chemical compounds