..... Click the link for more information. ); the stable form is a silver-gray, brittle crystalline solid that tarnishes rapidly in air, and at high temperatures burns to form a white cloud of arsenic trioxide. A yellow crystalline form and a black amorphous form are also known. Arsenic is a member of Group 5 of the periodic table periodic table, chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley . In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the
..... Click the link for more information. . It combines readily with many elements: with hydrogen to form arsine, an extremely poisonous gas; with oxygen to form a pentoxide and the above-mentioned trioxide (As2O3 or As4O6), a deadly poison also called arsenic (III) oxide, arsenious oxide, white arsenic, or, simply, arsenic; with the halogens; and with sulfur.
The element is used with other metals to make hard, strong, corrosion-resistant alloys. Its compounds are used in pigments, animal poisons, insecticides (e.g., Paris green Paris green, also called Schweinfurt green, an extremely poisonous, bright green powder that was formerly used extensively as a pigment (e.g., in wallpaper) and that is sometimes used as an insecticide or to kill plant fungi; it must be used with great caution
..... Click the link for more information. ), and poison gases poison gas, any of various gases sometimes used in warfare or riot control because of their poisonous or corrosive nature. These gases may be roughly grouped according to the portal of entry into the body and their physiological effects.
..... Click the link for more information. (such as lewisite) for chemical warfare. They are also used in glassmaking, in calico and indigo printing, in tanning and taxidermy (as preservatives), and in pyrotechnics. Small quantities of arsenic added to lead in the manufacture of shot assure perfectly spherical pellets by delaying the solidification of the molten lead, and thereby allowing it to flow more readily; the arsenic also contributes hardness. A small amount of arsenic is added to germanium in the production of semiconductor devices such as transistors and integrated circuits.
A number of organic compounds of arsenic are used in medicine; the best known is Salvarsan, formerly used extensively in the treatment of syphilis and yaws. On the other hand, many arsenic compounds are strong poisons. Even in dilute concentrations that are not poisonous, as are found in some water supplies, arsenic may be carcinogenic. One delicate test for the presence of even minute quantities of arsenic in compounds is the Marsh test Marsh test, method for the detection of arsenic , so sensitive that it can be used to detect minute amounts of arsenic in foods (the residue of fruit spray) or in stomach contents. The sample is placed in a flask with arsenic-free zinc and sulfuric acid.
..... Click the link for more information. .
Arsenic occurs in many ores, including realgar, orpiment, and arsenopyrite arsenopyrite (är'sĭnōpī`rīt, ärsĕn`ō–) or mispickel
..... Click the link for more information. , the chief commercial source. When it is prepared commercially from sulfide ores, e.g., arsenical pyrites, the ores are roasted (heated in the absence of air); the arsenic sublimes (passes directly from the solid to the gaseous state) and is condensed. In another method, white arsenic is reduced with carbon.
Although realgar, orpiment, and other arsenic minerals were known to the Greeks of Aristotle's time, the element itself was not. The "arsenic" so called by them and by the later alchemists was not true arsenic, but probably arsenic trioxide. The element was first described by Albertus Magnus in the 13th cent.
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