Arsenic is a chemical element that has the symbol As and atomic number 33. Its Atomic Mass is 74.92. Its Ionic Charge is (3-). This is a notoriously poisonous metalloid that has many allotropic forms: yellow (molecular non-metallic) and several black and gray forms (metalloids) are a few that are seen. Three metalloidal forms of arsenic with different crystal structures are found free in nature (the minerals arsenic sensu strictu and the much rarer arsenolamprite and pararsenolamprite), but it is more commonly found as arsenide and arsenate compounds. Several hundred such mineral species are known. Arsenic and its compounds are used as pesticides, herbicides, insecticides and various alloys.

The most common oxidation states for arsenic are -3 (arsenides: usually alloy-like intermetallic compounds), +3 (arsenates(III) or arsenites, and most organoarsenic compounds), and +5 (arsenates(V): the most stable inorganic arsenic oxycompounds). Arsenic also bonds readily to itself, forming, for instance, As-As pairs in the red sulfide realgar and square As43- ions in the arsenide skutterudite. In the +3 oxidation state, the stereochemistry of arsenic is affected by possession of a lone pair of electrons.

The term "arsenic" was found in the following pages:

Material database: Food Analysis Performance Assessment Scheme (FAPAS) - Test Material T07153 (Canned Fish)
Thermo Sponsors Postdoctoral Position for Speciation Analysis | EVISA's News
Material database: JRC - Joint Research Centre - BCR-414 - Trace elements in plankton
Link database: CBI: Austria legislation: Wood preserved with arsenic and chromium
Material database: IAEA - MEL International Atomic Energy Agency - IAEA-457 Marine Sediment
Material database: RECIPE Chemicals + Instruments GmbH - ClinChek 8842 Whole blood, lyophilized, trace elements level III: LOT 445
Material database: National Institute of Standards and Technology (NIST) - SRM 50c
Material database: International Atomic Energy Agency (IAEA) - IAEA-436A Tuna Fish Flesh Homogenate
Solid-phase extraction in speciation analysis | EVISA's News
Atomic Spectroscopy Virtual Symposium 'A is for Arsenic' | EVISA's Agenda of Events
Link database: Encyclopedia of Earth: Arsenic use in the United States
FDA Approves Inorganic Arsenic Limits in Baby Rice Cereal | EVISA's News
Link database: US EPA - Contaminant Focus - Arsenic
Material database: NIES - National Institute for Environmental Studies - CRM 28: Urban Aerosols
Material database: Canadian Certified Reference Materials Project (CCRMP) - CZN-3 Zinc Concentrate
Material database: National Institute of Standards and Technology (NIST) - SRM 2429 - Flue Gas Desulfurization Gypsum
Material database: Sigma-Aldrich - Matrix CRM - Soil, Sludge, Sediment: TCLP Metals - Sandy Loam 13
Arsenic, an element of archaic life ? | EVISA's News
Material database: IAEA - MEL International Atomic Energy Agency - IAEA-433 Trace Elements and Methylmercury in Marine Sediment
Material database: IRMM - Institute for Reference Materials and Measurements - BCR-422