Helium
Main page |
| Other names/abbreviations: | He |
| Element no: | 2 |
| Element group: | 18 (IUPAC) VIII A (American labelling) VIII B (European labelling) Noble gasses |
| Element type: | Nonmetals |
| CAS-Number: | 7440-59-7 |
| EINECS-Number: | 231-168-5 |
Chemical properties
Reaction of hydrogen with waterHelium does not react with water. It does, however, dissolve slightly to the extent of about 8.61 cm3/kg at 20 °C (293 K) [1].
Solubility
Water: 8.6 g/l (20 °C) [2]
Organic solvents: Insoluble (20 °C) [2]
Safety
Symbol: -R-phrases: -
S-phrases: 3-7
Physical properties
Appearance | ||
| Physical state @ 20°C: | Gas [2] | |
| Color: | Colourless [2] | |
| Odor: | Almost odourless [2] | |
Bulk properties | ||
| Molecular weight (g/mol): | 4.002602(2) [1] | |
| Melting point (°C): | -272 [2] | |
| Boiling point (°C): | -268.93 [1] | |
| Density (g/cm3): | 0.00017850 [1] | |
| Molar volume (cm3): | 57 (Critical) [3] | |
| Velocity of sound (m/s): | 970 | |
Optical properties | ||
| Refractive index: | 1.000035 (g) 1.028 (l) | |
Thermodynamic properties | ||
| ΔH°vaporization (kJ/mol): | 0.08 [1] | |
| Critical temperature (°C): | -267.96 [3] | |
Electronic properties | ||
 |
Electron configuration: | 1s2 |
Conductivity | ||
| Thermal (W/m·K): | 0.1418 (0 °C) [1] | |
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: Merck. ChemDAT The Merck Chemical Database Ver. 1.1.5
3: CRC Handbook of Chemistry and Physics
75th edition (1994) Edited by Lide,D.R. , CRC Press Inc. Boca Raton, USA
© Michael Pilgaard
Created: April 29, 2006
Last update: October 31, 2008