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Arsenic is the 53rd most abundant element in the Earth's crust, comprising about 1.5 parts per million (0.00015%). [45] Typical background concentrations of arsenic do not exceed 3 ng/m 3 in the atmosphere; 100 mg/kg in soil; 400 μg/kg in vegetation; 10 μg/L in freshwater and 1.5 μg/L in seawater. [46]
Radon is a chemical element; it has symbol Rn and atomic number 86. It is a radioactive noble gas and is colorless and odorless. Of the three naturally occurring radon isotopes, only 222 Rn has a sufficiently long half-life (3.825 days) for it to be released from the soil and rock where it is generated.
Arsenic is a ubiquitous naturally occurring chemical element, and the 20th most common element on Earth. [13] Arsenic levels in the groundwater vary from around 0.5 parts per billion to 5000 parts per billion, depending on an area's geologic features, and possible presence on industrial waste.
Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow. Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry. The alternation of abundance between even and odd atomic number is ...
Standard atomic weight Ar° (As) 74.921 595 ± 0.000 006[2] 74.922 ± 0.001 (abridged) [3] view. talk. edit. 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.
Arsenide. Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). In chemistry, an arsenide is a compound of arsenic with a less electronegative element or elements. Many metals form binary compounds containing arsenic, and these are called arsenides.
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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.