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This is arsenic.

Symbol As
Atomic number 33
Atomic mass 74.9216 amu

Arsenic, was discovered about 1250.

Distinguishing properties

Arsenic is classified as a semimetal. When heated, it sublimes.


Like antimony and bismuth, arsenic occurs in nature sulfide ores, As2S3, orpiment. It can also be found in ores of various metals such as copper, lead, silver, and mercury.

  • Orpigment
    The name orpigment is derived from the latin aurpigmentum meaning 'gold pigment'. This mineral was widely used by medieval artists as a gold yellow colourant.
    Gold imitation
    This arsenic compound was widely used to make many colours and to imitate gold.


Although all arsenic compounds are poisonous, some of its compounds were once medicines. But most of their uses in this area are now banned. Although 0.1 gram doses of arsenic are lethal to humans, traces of arsenic can stimulate the production of red blood cells.

See also

Periodic table of the elements