Search results
Results from the WOW.Com Content Network
Arsenic is also found in food, water, soil, and air. [132] Arsenic is absorbed by all plants, but is more concentrated in leafy vegetables, rice, apple and grape juice, and seafood. [ 133 ] An additional route of exposure is inhalation of atmospheric gases and dusts. [ 134 ]
Arsenic compounds have been known for at least 5000 years, and the ancient Greek Theophrastus recognized the arsenic minerals called realgar and orpiment. Elemental arsenic was discovered in the 13th century by Albertus Magnus. [14] Antimony was well known to the ancients. A 5000-year-old vase made of nearly pure antimony exists in the Louvre.
Arsenic (33 As) has 32 known isotopes and at least 10 isomers. Only one of these isotopes, 75 As, is stable; as such, it is considered a monoisotopic element. The longest-lived radioisotope is 73 As with a half-life of 80 days.
Arsenic is used as the group 15 element in the III-V semiconductors gallium arsenide, indium arsenide, and aluminium arsenide. [10] The valence electron count of GaAs is the same as a pair of Si atoms, but the band structure is completely different which results in distinct bulk properties. [ 11 ]
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.
Other reactions of main group compounds with yellow arsenic have been shown to involve units of arsenic with more than four atoms. In reaction with the silylene compound [PhC(NtBu) 2 SiN(SiMe 3) 2], an aggregation of As 4 was observed to form a cage compound of ten arsenic atoms, including a seven-membered arsenic ring at its center. [9]
In its standard state arsine is a colorless, denser-than-air gas that is slightly soluble in water (2% at 20 °C) [1] and in many organic solvents as well. [citation needed] Arsine itself is odorless, [5] but it oxidizes in air and this creates a slight garlic or fish-like scent when the compound is present above 0.5 ppm. [6]
The sulfur atoms of the thiol groups are the site of interaction with arsenic. This is because the thiol groups are nucleophilic while the arsenic atoms are electrophilic. Once bound to the chelating agent the molecules can be excreted, and therefore free inorganic arsenic atoms are removed from the body.