Arsenic

ARSENIC is a chemical element with 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 metalloid and has various allotropes, but only the gray form is important to industry. Arsenic is naturally present at high levels in the groundwater of a number of countries including the United States & Canada. The primary use of metallic arsenic is in alloys of lead (ex: in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the second most commonly used semiconductor after doped silicon. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides.