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Arsenic is a chemical element with the symbol As and the atomic number 33. It is a metalloid and one of the pnictogens , and therefore shares many properties with its group 15 neighbors phosphorus and antimony .
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.
The soils hold 1 to 10 parts per million of arsenic, and seawater carries 1.6 parts per billion of arsenic. Arsenic comprises 100 parts per billion of a typical human by weight. Some arsenic exists in elemental form, but most arsenic is found in the arsenic minerals orpiment, realgar, arsenopyrite, and enargite. [14]
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Whereas the mass number simply counts the total number of neutrons and protons and is thus an integer, the atomic mass of a particular isotope (or "nuclide") of the element is the mass of a single atom of that isotope, and is typically expressed in daltons (symbol: Da), or universal atomic mass units (symbol: u).
This is a list of chemical elements and their atomic properties, ordered by atomic number (Z).. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.
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Arsenic is the chemical element with symbol As and atomic number 33. Arsenic may also refer to: Arsenic trioxide, a poison commonly referred to as simply as "arsenic" Arsenic acid, a chemical compound with the formula H 3 AsO 4; Arsenic Lake, a lake in Ontario, Canada; Ärsenik, a French rap group; Mr. Arsenic, an America anthology television ...