Argon vs Rubidium
| Property | Ar Argon | Rb Rubidium |
|---|---|---|
| Atomic number | 18 | 37 |
| Symbol | Ar | Rb |
| Name | Argon | Rubidium |
| Category | noble-gas | alkali-metal |
| Standard Atomic Weight | 39.948 u | 85.4678 u |
| Period | 3 | 5 |
| Group | 18 | 1 |
| Block | p | s |
| Phase at STP | gas | solid |
| Electron configuration | [Ne]3s23p6 | [Kr]5s1 |
| Oxidation states | [0] | [-1, 1] |
| Electronegativity (Pauling) | N/A | 0.82 |
| Electron affinity | -1 eV | 0.4859 eV |
| Density | 1.7837 kg/m³ | 1530 kg/m³ |
| Melting point | -189.35 °C | 39.31 °C |
| Boiling point | -185.85 °C | 687.85 °C |
| Discovery year | 1894 | 1861 |