Albertus Magnus discovered the first element, Arsenic, in 1250. The element had been suspected for thousands of years before it was ever purified and identified.
Arsenic is an element in the Earth's crust that occurs naturally. It is usually with a variety of other elements including oxygen, sulfur and chlorine to form an inorganic compound. People may be exposed to arsenic if they work at hazardous waste sites. Exposure to high levels of this element can eventually cause death, and repeated exposure to low levels of arsenic can cause a discoloration on the skin and even the appearance of warts or corns.