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In As 4 S 10, arsenic has a formal oxidation state of +2 in As 4 S 4 which features As-As bonds so that the total covalency of As is still 3. [38] Both orpiment and realgar, as well as As 4 S 3, have selenium analogs; the analogous As 2 Te 3 is known as the mineral kalgoorlieite, [39] and the anion As 2 Te − is known as a ligand in cobalt ...
Arsenic forms colorless, odorless, crystalline oxides As 2 O 3 ("white arsenic") and As 2 O 5 which are hygroscopic and readily soluble in water to form acidic solutions. Arsenic(V) acid is a weak acid and the salts are called arsenates , [ 5 ] the most common arsenic contamination of groundwater , and a problem that affects many people.
A 2007 study found that over 137 million people in more than 70 countries are probably affected by arsenic poisoning of drinking water. The problem became a serious health concern after mass poisoning of water in Bangladesh. [1] Arsenic contamination of ground water is found in many countries throughout the world, including the US. [2]
Arsenic typically occurs in the oxidation states (III) and (V), illustrated by the halides AsX 3 (X = F, Cl, Br, I) and AsF 5. Correspondingly, organoarsenic compounds are commonly found in these two oxidation states. [3] The hydroxyarsenic compounds are known: [3] arsonous acids (RAs(OH) 2), rare (arsenous acid (As(OH) 3) is well known)
Arsenic is a metalloid with an atomic number of 33, and its common oxidation states are +3 or +5, as arsenate(As III) and arsenite(As V). [12] Arsenic is primarily found as organic arsenic compounds, inorganic arsenic compounds, and arsine gas.
Arsenate is the major arsenic form in oxidizing environments; however, in one study, bacteria from arsenic-contaminated soil at a smelter site was able to reduce As(+5) to As(+3) under anaerobic conditions at arsenic concentration as high as 75 mg/L. [3] Arsenate-respiring bacteria and Archaea have also recently been isolated from a diversity of natural environments, including freshwater ...
In 1787, German physician Johann Metzger (1739-1805) discovered that if arsenic trioxide were heated in the presence of carbon, the arsenic would sublime. [4] This is the reduction of As 2 O 3 by carbon: 2 As 2 O 3 + 3 C → 3 CO 2 + 4 As
Pearceite is one of the four so-called "ruby silvers", pearceite Cu(Ag,Cu) 6 Ag 9 As 2 S 11, pyrargyrite Ag 3 SbS 3, proustite Ag 3 AsS 3 and miargyrite AgSbS 2. [6] It was discovered in 1896 and named after Dr Richard Pearce (1837–1927), a Cornish–American chemist and metallurgist from Denver , Colorado.