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Gray, or metallic arsenic, pictured under an argon atmosphere. Gray arsenic, also called grey arsenic or metallic arsenic, is the most stable allotrope of the element at room temperature, and as such is its most common form. [1] This soft, brittle allotrope of arsenic has a steel gray, metallic color, and is a good conductor. [2]
This compound is generally regarded as stable, since at room temperature it decomposes only slowly. At temperatures of 250–300 °C decomposition to arsenic and hydrogen is rapid. [34] Several factors, such as humidity, presence of light and certain catalysts (namely aluminium) facilitate the rate of decomposition. [35]
The contribution of the muscle to the specific heat of the body is approximately 47%, and the contribution of the fat and skin is approximately 24%. The specific heat of tissues range from ~0.7 kJ · kg−1 · °C−1 for tooth (enamel) to 4.2 kJ · kg−1 · °C−1 for eye (sclera).
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]
Arsenic is a grey, metallic looking solid. It has a density of 5.727 g/cm 3 and is brittle, and moderately hard (more than aluminium; less than iron). [332] It is stable in dry air but develops a golden bronze patina in moist air, which blackens on further exposure. Arsenic is attacked by nitric acid and concentrated sulfuric acid.
The following table gives the crystalline structure of the most thermodynamically stable form(s) for elements that are solid at standard temperature and pressure. Each element is shaded by a color representing its respective Bravais lattice, except that all orthorhombic lattices are grouped together.
Arsenic trioxide powder.. Compounds of arsenic resemble in some respects those of phosphorus which occupies the same group (column) of the periodic table.The most common oxidation states for arsenic are: −3 in the arsenides, which are alloy-like intermetallic compounds, +3 in the arsenites, and +5 in the arsenates and most organoarsenic compounds.
Arsenic poisoning is a global problem arising from naturally occurring arsenic in ground water. The evidence that arsenic may be a beneficial nutrient at trace levels below the background to which living organisms are normally exposed has been reviewed. [3]