- Atomic Radius (Å)
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.
2
Atomic Number
4 u
Atomic Mass
null K
Melting Point
4.22 K
Boiling Point
0.18 g/liter
Density
0.49 Å
Atomic Radius
0.28 Å
Covalent Radius
24.59 eV
First Ionization Energy
-48
Electron Affinity
1
Number of Shells
2
Electron Shell Occupations
5.19 J/g
Specific Heat