| Symbol |
He |
|
| Atomic Number |
2 |
Relative Atomic Mass
12C = 12.0000 |
4.002602 |
Atomic Radius
pm |
128 |
First Ionisation Energy
kJ mol-1 |
2372.3 |
| Electronegativity |
5.50 |
Density
kg m-3 |
124.8 [b.p.]
0.1785 [273 K] |
Molar Volume
cm3 |
32.07 [4K] |
Thermal Conductivity
W m-1 K-1 |
0.152 [300 K] |
Melting Point
K |
0.95 (under pressure) |
Boiling Point
K |
4.216 |
| Number of Isotopes |
5 |
Ground State Electron
Configuration |
1s2 = [He] |
| Term Symbol |
1S0 |
| Discovery |
Observed by N. Lockyer and E. Frankland in the sun's spectrum during the eclipse of 1868. Isolated by Sir W. Ramsey (London, England) in 1895 and also by P.T. Cleve and N.A. Langlet (Uppsala, Sweden) |
| Name Derived From |
Greek helios meaning 'sun' |
Name in Other
Languages |
 Croatian | Helij |
 Danish | helium |
 Dutch | helium |
 Finnish | helium |
 French | hélium |
 German | Helium |
 Italian | elio |
 Norwegian | helium |
 Portuguese | hélio |
 Spanish | helio |
 Swedish | helium |
| Peter van der Krogt's Element Multidict - element name translations in over 48 langauges |
