Discovered | Name | Characteristics | Found | Prepared | Reactions | Uses

Antimony is in period 5 of the nitrogen group (Group VA), and is variously classed as a nonmetal or a metalloid. It may have oxidation numbers of -3, +3, and +5 in its compounds. Other members of Group VA are nitrogen (N), phosphorus (P), arsenic (As), and bismuth (Bi).

Compounds of antimony were recognized by the ancients, and it is said to have been separated from stibnite ore as a metal by Basilium Valentinus at the beginning of the seventeenth century. However, there is serious doubt about the validity of this or even of the existence of Valentinus. Antimony was first adequately described as an element by Leméry in 1707.

The name is derived from Latin anthemonium, which is probably derived from the Arabic word al ithymid, the name of Sb2S3 (stibnite), a compound that was used for mascara. The symbol Sb is derived from Latin stibium, which means "a mark".

As a crystalline solid Sb is silvery white and brittle, or it may be a gray powder. It is a poor conductor of heat and electricity.

In nature the element is sometimes found nearly pure, but more frequently as the sulfide, stibnite (Sb2S3), as antimonides and sulfantimonides of the heavy metals, or as oxides. There are extensive deposits of stibnite in China.

The element is extracted from the sulfide by roasting to the oxide,

2 Sb2S3(s) + 9 O2(g) 2 Sb2O3(s) + 6 SO2(g)

which is reduced by scrap iron or carbon.

Sb2O3(s) + 3 C(s) 2 Sb(s) + 3 CO(g)

Sb is not readily attacked by water, but it does react with air when heated to give white Sb2O3 and yellow Sb2O5.

The element reacts with fluorine, chlorine, and bromine and unites with hydrogen to form stibine, an unstable, poisonous gas.

Sb(s) + 3/2 H2(g) SbH3(g)

Metallic antimony is available commercially with a purity of 99.999+% and is widely used in alloys in a percentage varying from one to twenty. Alloys include Britannia metal, type metal, babbit metal, and sometimes pewter. All are hard, brittle, have low melting points, and expand upon solidifying, thereby retaining fine details of a mold. Antimony greatly increases the hardness and mechanical strength of lead.

Batteries, antifriction alloys, type metal, cable sheathing, and minor products use about half of the metal. Compounds taking up the other half are oxides, sulfides, sodium antimonate, and antimony trichloride. These are used in the manufacture of flame-proofing compounds, as red pigment in paints, in ceramic enamels, glass and pottery.

Antimony and some of its compounds are toxic, and the maximum allowable concentration of antimony dust in the air is recommended to be no more than 0.5 mg/m3. Nonetheless, the introduction of antimony compounds to treat parasitic diseases is regarded as "one of the milestones in the history of therapeutics." For example, tartar emetic (hydrated potassium antimonyl tartrate) is still used as a medicine to treat schistosoma.

Antimony has been mixed with soot and other substances to make kohl, an eye cosmetic used for centuries, and its compounds are used as mordants to fix dyes to fabrics.