a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250. A rsenic is a metalloid. It can exist in various allotropes, although only the gray form has important use in industry.

Arsenic was the poison of choice until its detection became easy. Combined with gallium it forms a semiconductor used in creating high-speed integrated circuits for supercomputers and cell phones.