Helium vs Iridium
| Property | He Helium | Ir Iridium |
|---|---|---|
| Atomic number | 2 | 77 |
| Symbol | He | Ir |
| Name | Helium | Iridium |
| Category | noble-gas | transition-metal |
| Standard Atomic Weight | 4.002602 u | 192.217 u |
| Period | 1 | 6 |
| Group | 18 | 9 |
| Block | s | s |
| Phase at STP | gas | solid |
| Electron configuration | 1s2 | [Xe]6s24f145d7 |
| Oxidation states | [0] | [-3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9] |
| Electronegativity (Pauling) | N/A | 2.2 |
| Electron affinity | -0.5 eV | 1.565 eV |
| Density | 0.1785 kg/m³ | 2.256220e+4 kg/m³ |
| Melting point | -272.2 °C | 2445.85 °C |
| Boiling point | -268.93 °C | 4427.85 °C |
| Discovery year | 1868 | 1803 |