|Atomic mass||74.9216 amu|
Arsenic, was discovered about 1250.
Arsenic is classified as a semimetal. When heated, it sublimes.
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.