Arsenic
Arsenic is a chemical element; it has symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a notoriously toxic metalloid. It has various allotropes, but only the grey form, which has a metallic appearance, is important to industry.
This article is about the chemical element. For the poison commonly called "arsenic", see arsenic trioxide. For other uses, see Arsenic (disambiguation).Arsenic
- /ˈɑːrsənɪk/
(AR-sən-ik) - as an adjective: /ɑːrˈsɛnɪk/
(ar-SEN-ik)
grey (most common), yellow, black (see Allotropes of arsenic)
metallic grey
$_$_$DEEZ_NUTS#1__answer--3DEEZ_NUTS$_$_$
33
[Ar] 3d10 4s2 4p3
2, 8, 18, 5
887 K (615 °C, 1137 °F)
grey: 5.782 g/cm3[3]
5.22 g/cm3
1090 K, 3628 kPa[4]
1673 K, ? MPa
grey: 24.44 kJ/mol
34.76 kJ/mol (?)
24.64 J/(mol·K)
Pauling scale: 2.18
- 1st: 947.0 kJ/mol
- 2nd: 1798 kJ/mol
- 3rd: 2735 kJ/mol
- (more)
empirical: 119 pm
119±4 pm
185 pm
grey: rhombohedral (hR2)
5.6 µm/(m⋅K)[7] (at r.t.)
50.2 W/(m⋅K)
333 nΩ⋅m (at 20 °C)
−5.5×10−6 cm3/mol[9]
8 GPa
22 GPa
3.5
1440 MPa
7440-38-2
Arabic alchemists (before AD 815)
The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices. It is also a component of the III–V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the increasing recognition of the toxicity of arsenic and its compounds.[11]
A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, goats, chickens, and presumably other species. A role in human metabolism is not known.[12][13] However, arsenic poisoning occurs in multicellular life if quantities are larger than needed. Arsenic contamination of groundwater is a problem that affects millions of people across the world.
The United States' Environmental Protection Agency states that all forms of arsenic are a serious risk to human health.[14] The United States' Agency for Toxic Substances and Disease Registry ranked arsenic as number 1 in its 2001 Priority List of Hazardous Substances at Superfund sites.[15] Arsenic is classified as a Group-A carcinogen.[14]
Environmental issues[edit]
Exposure[edit]
Naturally occurring sources of human exposure include volcanic ash, weathering of minerals and ores, and mineralized groundwater. Arsenic is also found in food, water, soil, and air.[123] Arsenic is absorbed by all plants, but is more concentrated in leafy vegetables, rice, apple and grape juice, and seafood.[124] An additional route of exposure is inhalation of atmospheric gases and dusts.[125] During the Victorian era, arsenic was widely used in home decor, especially wallpapers.[126]