- 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