Helium

Latin nameHelium
English nameHelium
chemical symbolHe
atomic number2
relative atomic mass4.002602
period18
groupVIII.A
classificationnoble gases
discovery date1868
discovererJanssen, 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 states0
electron configuration1s2
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 conditionsgas

Helium facts

Helium is a colorless, light, monoatomic noble gas. Under normal conditions, does not create any helium stable compounds.

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