Helium vs Europium
| Property | He Helium | Eu Europium |
|---|---|---|
| Atomic number | 2 | 63 |
| Symbol | He | Eu |
| Name | Helium | Europium |
| Category | noble-gas | lanthanide |
| Standard Atomic Weight | 4.002602 u | 151.964 u |
| Period | 1 | 6 |
| Group | 18 | N/A |
| Block | s | s |
| Phase at STP | gas | solid |
| Electron configuration | 1s2 | [Xe]6s24f7 |
| Oxidation states | [0] | [0, 2, 3] |
| Electronegativity (Pauling) | N/A | N/A |
| Electron affinity | -0.5 eV | 0.116 eV |
| Density | 0.1785 kg/m³ | 5240 kg/m³ |
| Melting point | -272.2 °C | 821.85 °C |
| Boiling point | -268.93 °C | 1528.85 °C |
| Discovery year | 1868 | 1896 |