Argon

Symbol: Ar
Atomic number: 18
Category: noble gases
Group: 18
Period: 3
Block: p
Atomic weight: 39.948 g/mol
Electrons per shell: 2, 8, 8
CAS number: 7440-37-1
Phase: gas
Density: 1.784 g/l (0C, 101.325 kPa)
Melting point: 83.80 K (-189.35C, -308.83F)
Boiling point: 87.30 K (-185.85C, -302.53F)
Crystal structure: cubic face centered
Oxidation states: 0
Electronegativity: inert
Name's origin: argon
Name's meaning: a Greek word which means 'inactive' due to the element's inactivity
Facts:
- is present in the Earth's atmosphere at 0.93% by volume
- is the most abundant and most frequently used of the noble gases
- is colorless, odorless, tasteless and nontoxic in both its liquid and gaseous forms
- up until 1957 its symbol was o
- argon was thought to be inert and unable to form any compounds, but in August 2000 the first argon compound was formed by the researchers in Finland - by shining ultraviolet light onto frozen argon containing a small amount of hydrogen fl
- is used e.g as a fire extinguisher gas, metal inert gas welding, as a preservative and in laboratory gloveboxes
- cryosurgery procedures such as cryoablation use liquefied argon to destroy cancer cells
- although argon is non-toxic, it does not satisfy the body's need for oxygen and is thus an asphyxiant