Helium
| Latin name | Helium |
| English name | Helium |
| chemical symbol | He |
| atomic number | 2 |
| relative atomic mass | 4.002602 |
| period | 18 |
| group | VIII.A |
| classification | noble gases |
| discovery date | 1868 |
| discoverer | Janssen, Ramsey Frankland, Lockyer |
| melting point [°C] | -272,2 |
| boiling point [°C] | -268,93 |
| critical temperature [°C] | -267,96 |
| critical pressure [MPa] | 0,227 |
| density [g cm-3] | 0,0001787 |
| electronegativity [Pauling] | 3,89 |
| oxidation states | 0 |
| electron configuration | 1s2 |
| atomic radius [pm] | 31 |
| covalent radius [pm] | 32 |
| specific heat [J g-1K-1] | 5,193 |
| heat of fusion [kJ mol-1] | - |
| thermal conductivity [W m-1 K-1] | 0,1513 |
| 1. ionizing energy [kJmol-1] | 2372,323 |
| 2. ionizing energy [kJmol-1] | 5250,512 |
| state at normal conditions | gas |
Helium is a colorless, light, monoatomic noble gas. Under normal conditions, does not create any helium stable compounds.
Resources
- BÍNA, Jaroslav; et al. Malá encyklopedie chemie. Praha: SNTL, 1976.
- EMSLEY, John. The Elements. Oxford: Clarendon Press, 1998. ISBN 9780198558187.
- HARRIS, Robin. Helium-filled drives announced. In: ZDNet [online]. 2012-09-13 [cit. 2012-09-20]. Available from: http://www.zdnet.com/
- STWERTKA, Albert. A Guide to the Elements. Oxford: University Press, 2002. ISBN 0-19-515027-9.
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