Helium vs Bromine
| Property | He Helium | Br Bromine |
|---|---|---|
| Atomic number | 2 | 35 |
| Symbol | He | Br |
| Name | Helium | Bromine |
| Category | noble-gas | halogen |
| Standard Atomic Weight | 4.002602 u | 79.904 u |
| Period | 1 | 4 |
| Group | 18 | 17 |
| Block | s | p |
| Phase at STP | gas | liquid |
| Electron configuration | 1s2 | [Ar]4s23d104p5 |
| Oxidation states | [0] | [-1, 1, 2, 3, 4, 5, 7] |
| Electronegativity (Pauling) | N/A | 2.96 |
| Electron affinity | -0.5 eV | 3.3635 eV |
| Density | 0.1785 kg/m³ | 3102.8 kg/m³ |
| Melting point | -272.2 °C | -7.2 °C |
| Boiling point | -268.93 °C | 58.8 °C |
| Discovery year | 1868 | 1825 |