Arsenic is a semi-metallic element. Arsenic and its compounds are known to be toxic.

Arsenic has two forms. The grey metallic version has a density of 5.73g/cm3 and the yellow form that has a density of 1.97g/cm3.
Discovery

While arsenic has been in use since ancient times, in applications such as the hardening of bronze, its discovery has been attributed to Albertus Magnus in 1250AD. He isolated arsenic when he heated soap and orpiment (arsenic trisulphide, As2S3).
Occurrence

Although arsenic can be found in elemental form, it is most commonly found in minerals such as Mispickel (arsenopyrite, FeSAs) which is found in France, Germany, Italy, Romania, Siberia and North America.

Arsenic is also found in other minerals such as:

· Realgar As4S4

· Orpiment As2S3

· Arsenolite As2O3

· Loellingite FeAs2
Production

Arsenic is produce by heating arsenic-bearing minerals in the absence of air. E.g.

Key Properties

· Arsenic and its compounds are known to be toxic

· Arsenic does not melt, it sublimes, going directly from a solid to a gas



Property





Value

Symbol





As

Atomic Number





33

Atomic Weight





74.92

CAS Number





7440-38-2

Density





5.73g/cm3

Melting point





817˚C

Boiling Point





617˚C

Specific Heat





330J/kg.K

Electronegativity





2.18

Applications
Metallurgy

Arsenic is used as an additive for metallurgical purposes due to its semi-metallic properties. Examples include: adding 2% to lead to produce lead shot where the addition increases sphericity; a 3% addition to lead alloys increases mechanical properties and high temperature properties; and 0.15-0.50% addition to copper for high temperature applications.