Element Antimony, Sb, Metalloid
About AntimonyWith antimony we commence the consideration of the metals of the tin group, in which a number of elements are classed together belonging to different natural families and forming corresponding sub-groups. Their common characteristic is the predominating tendency to form acid compounds in place of the basic ones yielded by the other metals. Their oxides, especially those comparatively rich in oxygen, behave as the anhydrides of acids, and their sulphur compounds dissolve in the solutions of the alkali sulphides with formation of thio-salts (vide infra). The last characteristic which is of importance in analytical chemistry has given rise to the formation of the whole group, and the relations which are here met with will be presently discussed in greater detail.
On account of the manifold and widely extending affinity relations existing between the elements, we shall repeatedly find resemblances to other groups, and it would be possible to class several of the elements considered here along with others previously discussed. By reason, however, of the variety of the relationships, a system of the elements, sufficient in all respects, cannot be framed, and the arrangement which has here been retained has therefore been determined chiefly by didactic considerations.
Antimony is allied on the one hand to bismuth, and on the other, to arsenic and phosphorus. It therefore forms a transition element between the metals and the non-metals, but is still essentially on the side of the metals. Its combining weight is Sb = 120.2.
Antimony is a grey-white, lustrous metal, having the density 6.7; from the fused mass it solidifies in a distinctly crystalline form, and is at all temperatures so brittle that it can be easily ground or pounded to a powder. It melts at a red-heat, and volatilises at a high temperature. The vapour exhibits a variable molar weight in the neighbourhood of 290. This number corresponds to no simple formula, but lies between Sb2 and Sb3; probably, therefore, we are dealing with a mixture of different kinds of vapour, perhaps Sb4 and Sb.
In the potential series antimony stands beside bismuth; it does not, therefore, decompose dilute acids, and it also remains unchanged in the air. On being heated it readily oxidises; a piece of antimony fused on charcoal before the blowpipe, continues to glow even after the flame has been removed, the antimony burning to antimony oxide. If a small globe of strongly heated antimony is thrown on a piece of paper with upturned edges, it skips about on this, burning all the while, and leaves very regularly marked, hyperbolic trails.
Besides the ordinary antimony, an allotropic form of less stability is known, which is obtained as a silver-white metal, of density 5.78, by slowly decomposing a concentrated solution of antimony chloride in hydrochloric acid with the electric current. The metal which is deposited falls to a powder with slight explosion on being scratched by a sharp body, ordinary grey antimony being formed with considerable evolution of heat. This allotropic metal is not pure, but contains antimony chloride, the amount of which varies with the conditions of the experiment. |
Antimony History| Antimony is known from high antiquity. Oriental countries were familiar with Antimony houseware at least as early as 3000 BC. In ancient Egypt in 19th century BC antimonite powder (natural Sb2S3) called mesten or stem was used for eyebrows blacking. In ancient Greek it was known as as stimi and stibi, from which Latin stibium derived. This element is called antimonium since 12-14 centuries BC. In 1789 Lavoisier put Antimony into the chemical elements list under the name antimoine related to English antimony. Spanish and Italian antimonio, German Antimon. Russian "surma" appears from Turkish powder surme, lead glance PbS, also used for eyebrows blacking (alternative interpretation: comes from Persian word "surma" which means "metal"). 15th century German alchemist Basilius Valentinus, also known as Basil Valentine, gave detailed description of antimony's properties and extraction methods. |
Antimony OccurrenceAverage crustal abundance of antimony is 5x10-5 % by mass. Antimony is dispersed in magma and biosphere. It is concentrated in hydrothermal sources from hot underground waters. Antimony forms its own deposits as well as antimony-mercury, antimony-lead, gold-antimony, antimony-tungsten ones. Among 27 antimonial minerals stibnite, sometimes also called antimonite (Sb2S3) is the most important commercially. Due to its sulphur affinity antimony often forms an impurity in sulphides of such elements as arsenic, bismuth, nickel, lead, mercury, argentum and others elements.
Antimony's abundance per 100 g of dry matter is 0.006 mg, 0.02 mg in organisms of sea creatures and 0.0006 mg in terrestrial animals. Human and animals organisms are supplied with antimony through respiratory organs or digestive tract. It is extracted from organism by faces and, in insignificant amounts, with urine. Antimony's biological role remains unknown. It is separated in the thyroid liver and the spleen. Antimony is accumulated in erythrocytes mostly as Sb+3, in blood plasma. Antimony Maximum Permissible Concentration (MPC) is 10-5 - 10-7 g per 100 g of dry fabric. When MPC is exceeded antimony deactivates enzymes of lipid, carbohydrate and protein metabolism, perhaps as a result of sulfhydryl groups blocking. |
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