Arsenic is 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. Arsenic is a metalloid.
Three reasons Arsenic stands out
- 1
Historically used in poison and pesticides.
- 2
Its trioxide compound is used in modern medicine to treat a specific form of leukaemia.
- 3
Victorian green wallpaper pigments often contained a highly toxic compound of this element, potentially sickening residents.
A metalloid with a dark reputation
Arsenic is infamous as a poison, but its story also includes pigments, medicines, semiconductors, and natural groundwater contamination. Different chemical forms vary greatly in toxicity. Gallium arsenide, for example, is a crystalline electronic material whose behavior bears little resemblance to elemental arsenic.