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The Element Argon

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18

Ar

Argon

39.948

Atomic Number: 18

Atomic Weight: 39.948

Melting Point: 83.80 K (-189.35°C or -308.83°F)

Boiling Point: 87.30 K (-185.85°C or -302.53°F)

Density: 0.0017837 grams per cubic centimeter

Phase at Room Temperature: Gas

Element Classification: Non-metal

Period Number: 3    Group Number: 18    Group Name: Noble Gas

What's in a name? From the Greek word for inactive, argos.

Say what? Argon is pronounced as AR-gon.

History and Uses:

Argon was discovered by Sir William Ramsay, a Scottish chemist, and Lord Rayleigh, an English chemist, in 1894. Argon makes up 0.93% of the earth's atmosphere, making it the third most abundant gas. Argon is obtained from the air as a byproduct of the production of oxygen and nitrogen.

Argon is frequently used when an inert atmosphere is needed. It is used to fill incandescent and fluorescent light bulbs to prevent oxygen from corroding the hot filament. Argon is also used to form inert atmospheres for arc welding, growing semiconductor crystals and processes that require shielding from other atmospheric gases.

Once thought to be completely inert, argon is known to form at least one compound. The synthesis of argon fluorohydride (HArF) was reported by Leonid Khriachtchev, Mika Pettersson, Nino Runeberg, Jan Lundell and Markku Räsänen in August of 2000. Stable only at very low temperatures, argon fluorohydride begins to decompose once it warms above -246°C (-411°F). Because of this limitation, argon fluorohydride has no uses outside of basic scientific research.

Estimated Crustal Abundance: 3.5 milligrams per kilogram

Estimated Oceanic Abundance: 4.5×10-1 milligrams per liter

Number of Stable Isotopes: 3   (View all isotope data)

Ionization Energy: 15.760 eV

Oxidation States: 0

Electron Shell Configuration:

1s2

2s2   2p6

3s2   3p6