Mercury vs Bromine
The periodic table’s only two liquids at room temperature — one a shiny metal, one a red-brown fuming nonmetal.
Side by side
| Property | Mercury | Bromine |
|---|---|---|
| Symbol | Hg | Br |
| Atomic number (Z) | 80 | 35 |
| Atomic mass | 200.59 u | 79.904 u |
| Category | Transition metal | Halogen |
| Group | 12 | 17 |
| Period | 6 | 4 |
| Phase at room temp | liquid | liquid |
| Electron configuration | [Xe] 4f^14 5d^10 6s^2 | [Ar] 3d^10 4s^2 4p^5 |
| Valence electrons | 2 | 7 |
| Atomic radius | 171 pm | 94 pm |
| Electronegativity | 2 | 2.96 |
| First ionisation energy | 1007 kJ/mol | 1140 kJ/mol |
The verdicts
- Bigger atom: Mercury — the lower an element sits in its group, the more shells it wears.
- Greedy electron-taker: Bromine — higher electronegativity means it pulls shared electrons harder.
- Heavier: Mercury — compare the atomic masses in the table above.
Want the visual version with bars for radius, electronegativity and ionisation energy? Open the interactive compare tool with this pair already loaded.