Argon vs Astatine
| Property | Ar Argon | At Astatine |
|---|---|---|
| Atomic number | 18 | 85 |
| Symbol | Ar | At |
| Name | Argon | Astatine |
| Category | noble-gas | halogen |
| Standard Atomic Weight | 39.948 u | 210 u |
| Period | 3 | 6 |
| Group | 18 | 17 |
| Block | p | p |
| Phase at STP | gas | solid |
| Electron configuration | [Ne]3s23p6 | [Xe]6s24f145d106p5 |
| Oxidation states | [0] | [-1, 1, 3, 5, 7] |
| Electronegativity (Pauling) | N/A | 2.2 |
| Electron affinity | -1 eV | 2.391 eV |
| Density | 1.7837 kg/m³ | 7000 kg/m³ |
| Melting point | -189.35 °C | 301.85 °C |
| Boiling point | -185.85 °C | -273.15 °C |
| Discovery year | 1894 | 1940 |