| Attribute | Sodium × | Rubidium × |
|---|---|---|
| Atomic mass (u) | 22.9897693 | 85.468 |
| Standard state | Solid | Solid |
| Oxidation states |
|
|
| Electron configuration | [Ne]3s¹ | [Kr]5s¹ |
| Atomic radius (van der waals) (pm) | 227 | 303 |
| Electronegativity (pauling scale) | 0.93 | 0.82 |
| Electron affinity (eV) | 0.548 | 0.468 |
| Ionization energy (eV) | 5.139 | 4.177 |
| Boiling point (K) | 1156 | 961 |
| Melting point (K) | 370.95 | 312.46 |
| Density (g/cm³) | 0.97 | 1.53 |
| Atomic number | 11 | 37 |
| Group name | Alkali metal | Alkali metal |
| Discovered (year) | 1807 | 1861 |
| Symbol | Na | Rb |