Arsenic, with the chemical symbol As, is a semi-metallic element whose discovery dates back to ancient times. It has been used since antiquity and was later isolated in the 13th century by the German alchemist Albertus Magnus. Arsenic is relatively common on Earth and is found in various minerals, including arsenopyrite and realgar.
The applications of arsenic are diverse, but due to its toxicity, its use is heavily restricted. Historically, it was used in medicine, in agriculture as a pesticide, and in the wood preservative industry. Modern applications include electronics, the semiconductor industry, and alloy manufacturing. Arsenic compounds are extensively researched to understand their role in cancer therapy and the treatment of certain diseases.