Helium vs Barium
| Property | He Helium | Ba Barium |
|---|---|---|
| Atomic number | 2 | 56 |
| Symbol | He | Ba |
| Name | Helium | Barium |
| Category | noble-gas | alkaline-earth-metal |
| Standard Atomic Weight | 4.002602 u | 137.327 u |
| Period | 1 | 6 |
| Group | 18 | 2 |
| Block | s | s |
| Phase at STP | gas | solid |
| Electron configuration | 1s2 | [Xe]6s2 |
| Oxidation states | [0] | [1, 2] |
| Electronegativity (Pauling) | N/A | 0.89 |
| Electron affinity | -0.5 eV | 0.1447 eV |
| Density | 0.1785 kg/m³ | 3620 kg/m³ |
| Melting point | -272.2 °C | 726.85 °C |
| Boiling point | -268.93 °C | 1896.85 °C |
| Discovery year | 1868 | 1808 |