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Arsenic (As)

a semi-metal commonly used as a poison



atomic number 33
atomic mass 74.9216 amu

melting point 817.0C (1502.6F)
boiling point 613.0C (1135.4F)

When heated in the air, arsenic turns directly into a vapor (a process known as sublimation).

Arsenic conducts electricity easily.

Arsenic appears in yellow, black, and gray forms, with the gray form being the most common.

Occurence and Sources

Arsenic is found throughout the world, usually in conjuction with sulfur and metals, with the most common arsenic-bearing minerals being mispickel, orpiment, realgar, arsenolite, and arsenopyrite. It is usually recovered as a byproduct from the purification of copper, gold, or lead.



About 50% of the world arsenic supply comes from China, followed by Chile, Peru, and Morocco.


Arsenic has been used as a poison for hundreds of years, due to its extreme toxicity to insects, bacteria and fungi. Some arsenic compounds, however, are used in cancer medicines and stimulants. It is also used in semiconductors, and to strengthen alloys of copper, lead, and other metals.


Known since ancient times, arsenic was first isolated by Albertus Magnus about 1250. Its name comes from arsenikos, the ancient Greek word for "male" (the Greeks believed metals differed in sex).

See Also


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The Robinson Library >> Chemical Elements

This page was last updated on 08/14/2018.