Helium vs Beryllium
| Property | He Helium | Be Beryllium |
|---|---|---|
| Atomic number | 2 | 4 |
| Symbol | He | Be |
| Name | Helium | Beryllium |
| Category | noble-gas | alkaline-earth-metal |
| Standard Atomic Weight | 4.002602 u | 9.012183 u |
| Period | 1 | 2 |
| Group | 18 | 2 |
| Block | s | s |
| Phase at STP | gas | solid |
| Electron configuration | 1s2 | [He]2s2 |
| Oxidation states | [0] | [0, 1, 2] |
| Electronegativity (Pauling) | N/A | 1.57 |
| Electron affinity | -0.5 eV | -0.52 eV |
| Density | 0.1785 kg/m³ | 1850 kg/m³ |
| Melting point | -272.2 °C | 1286.85 °C |
| Boiling point | -268.93 °C | 2470.85 °C |
| Discovery year | 1868 | 1797 |