Helium
Elemental State He
Electron Configuration 1s2
First Ionization Potential 24.587 eV
Electron Affinity  
Z* 1.688 (Clementi-Raimondi)
Pauling Electronegativity  
Covalent Radius  
Metallic Radius  
Ionic Radius  
van der Waal's Radius 1.40 Å
Melting Point less than –272.2 oC at 26 atm
Boiling Point –268.93 oC
Density 0.1785 g/L (0 oC)
Other Properties