Relative atomic mass: 39.948 +- 0.001

English: Argon
French: Argon
Croatian: Argon
German: Argon
Italian: Argo
Spanish: Argon

Atomic number: 18
Group numbers: 18
Period: 3
Standard state (20 oC): gas

Discovery: 1894 Lord Raleigh, Sir William Ramsay (GB)
Argon was discovered by Lord Raleigh and Sir William Ramsay (GB) in 1894. The origin of the name comes from the Greek word argos meaning inactive. It is a colourless and odourless noble gas, chemically inert. Argon is the third most abundant element in the earth's atmosphere and makes up about 1%. Argon is continuously released into the air by decay of radioactive potassium-40. Pure form is obtained from fractional distillation of liquid air. It is used in lighting products, and is often used in filling incandescent light bulbs. Some is mixed with krypton in fluorescent lamps. Crystals in the semiconductor industry are grown in argon atmospheres. The price of 99.999 % pure argon gas costs 169.90 /dm3 in small quantities (1 dm3) and about 1.84 /dm3 in large quantities (300 dm3).
Electronic configuration: [Ne] 3s2 3p6
Formal oxidation number: 0
Atomic radius: 188 pm

Electronegativities: -
Thermal conductivity: 0.0179 W/(m K)
Electrical resistivity (20 oC): - microOhm cm

Melting point: -189.34 oC
Boiling point: -185.89 oC

Heat of fusion: 1.21 kJ/mol
Heat of vaporization: 6.53 kJ/mol
Heat of atomization: 0 kJ/mol

17Cl <= 18Ar => 19K

ASCII Periodic Table of the Elements
29 Aug. 2017
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