Argon vs Francium
| Property | Ar Argon | Fr Francium |
|---|---|---|
| Atomic number | 18 | 87 |
| Symbol | Ar | Fr |
| Name | Argon | Francium |
| Category | noble-gas | alkali-metal |
| Standard Atomic Weight | 39.948 u | 223 u |
| Period | 3 | 7 |
| Group | 18 | 1 |
| Block | p | s |
| Phase at STP | gas | solid |
| Electron configuration | [Ne]3s23p6 | [Rn]7s1 |
| Oxidation states | [0] | [1] |
| Electronegativity (Pauling) | N/A | 0.7 |
| Electron affinity | -1 eV | 0.491 eV |
| Density | 1.7837 kg/m³ | 1870 kg/m³ |
| Melting point | -189.35 °C | 26.85 °C |
| Boiling point | -185.85 °C | -273.15 °C |
| Discovery year | 1894 | 1939 |