Noble gas (data page) Atomic properties Atomic properties

| Atomic_property | Helium | Neon | Argon | Krypton | Xenon | Radon |
|---|---|---|---|---|---|---|
| Atomic number | 2 | 10 | 18 | 36 | 54 | 86 |
| Relative atomic mass | 4.002602(2) | 20.1797(6) | 39.948(1) | 83.80(1) | 131.29(2) | (222) |
| Number of natural s isotope | 2 | 3 | 3 | 6 | 9 | (1) |
| Outer shell electron configuration | 1s 2 | 2s 2 2p 6 | 3s 2 3p 6 | 4s 2 4p 6 | 5s 2 5p 6 | 6s 2 6p 6 |
| Atomic radius ( pm ) | 130 | 160 | 192 | 198 | 218 | – |
| Ionization energy (kJ/mol) | 2372 | 2080 | 1520 | 1351 | 1170 | 1037 |
| Static polarizability (Å 3 ) | 0.204 | 0.392 | 1.63 | 2.465 | 4.01 | – |
| Average Valence Electron Energy (AVEE) | 4.16 | 4.79 | 3.24 | 2.97 | 2.58 | – |