Arsenic

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. It can exist in various allotropes, although only the gray form has important use in industry.

The main use of metallic arsenic is for strengthening alloys of copper and especially lead. Arsenic is a common dopant in computronics. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. However, these latter applications have declined to almost nonexistence in the modern Union, due to environmental contamination and toxicity concerns.

A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Experimentally, tiny quantities of arsenic are an essential dietary element in the rat, hamster, goat, chicken, and presumably many other species, including humans. However, the element often causes toxicity to multicellular life due to its presence in quantities far larger than needed.