Argon
Main page |
| Other names/abbreviations: | Ar |
| Element no: | 18 |
| Element group: | 18 (IUPAC) VIII A (American labelling) VIII B (European labelling) Noble gasses |
| Element type: | Nonmetals |
| CAS-Number: | 7440-37-1 |
| EINECS-Number: | 231-147-0 |
Chemical properties
Reaction of argon with waterArgon does not react with water. It does, however, dissolve slightly to the extent of about 33.6 cm3/kg at 20 °C (293 K) [1].
Solubility
Water: 34 g/L (20 °C) [3]
Organic solvents: Insoluble (20 °C) [3]
Physical properties
Appearance | ||
| Physical state @ 20°C: | Gas [3] | |
| Color: | Liquid: Colorless [2] Gas: Colorless [2,3] | |
| Odor: | Liquid: None [2] Gas: None [2] | |
Bulk properties | ||
| Molecular weight (g/mol): | 39.948(1) [1] | |
| Melting point (°C): | -189.37 [1] | |
| Boiling point (°C): | -185.86 [1] | |
| Density (g/cm3): | 0.0017838 [1] | |
| Molar volume (cm3): | 22.56 | |
| Velocity of sound (m/s): | 319 | |
Thermodynamic properties | ||
| ΔH°vaporization (kJ/mol): | 6.52 [1] | |
| Critical temperature (°C): | -122.28 [2] | |
Electronic properties | ||
 |
Electron configuration: | 1s2-2s2-2p6-3s2-3p6 |
Conductivity | ||
| Thermal (W/m·K): | 0.0169 (0 °C) [1] | |
Occurence, isolation & synthesis
OccurenceThe atmosphere contains 0.94% argon [2].
Isolation
Argon is prepared by fractionation of air [2].
History
DiscoveryThe existence of argon in air was suspected by Cavendish in 1785, but it wasn't discovered until 1894, by Lord Rayleigh and Sir William Ramsay [2].
Origin of name
From the Greek word "argos" meaning "inactive" [2].
References
1: Greenwood,N.N., Earnshaw,A. Chemistry of the elements2nd edition (1997) Edited by Greenwood,N.N., Earnshaw,A. pp. 1-1340, Butterworth-Heinemann. Oxford. Great Britain
2: CRC Handbook of Chemistry and Physics
75th edition (1994) Edited by Lide,D.R. , CRC Press Inc. Boca Raton, USA
3: Merck. ChemDAT The Merck Chemical Database Ver. 1.1.5
© Michael Pilgaard
Created: April 29, 2006
Last update: May 5, 2008