Mercury
transition metalProperties
| Property | Value |
|---|---|
| Atomic Mass | 200.59 amu |
| Category | transition metal |
| Group | 12 |
| Period | 6 |
| Electron Configuration | [Xe] 4f14 5d10 6s2 |
| Electronegativity | 2 (Pauling) |
| Oxidation States | 2, 1 |
| Melting Point | 234.32 K (-38.8 °C) |
| Boiling Point | 629.88 K (356.7 °C) |
| Density | 13.534 g/cm³ |
About Mercury
Mercury is the textbook case for relativistic chemistry. The 6s electrons orbit so fast that they contract toward the nucleus, the 6s² pair becomes inert, and the metallic bonding between atoms collapses — which is why Hg is liquid at room temperature when its neighbor cadmium melts at 594 K. The symbol Hg comes from hydrargyrum, Greek for water-silver, and the metal has been worked since antiquity. In the lab you mostly meet it as the dense (13.534 g/cm³) silvery liquid in old barometers and Toepler pumps, or as Hg(II) salts like HgCl₂. Its toxicology is what shapes modern handling: organomercury compounds like dimethylmercury cross the blood-brain barrier with grim efficiency, and Karen Wetterhahn's death in 1997 changed how chemists treat the entire class. The Minamata Convention is now phasing it out of thermometers, dental amalgam, and chlor-alkali cells, leaving fluorescent lamps and small-scale gold mining as the stubborn holdouts.
Fun Fact
Mercury is liquid at room temperature because of Einstein's relativity — its inner electrons move at about 58 percent the speed of light, causing relativistic mass increase that contracts electron orbitals and weakens the bonds between mercury atoms.
Common Uses
- Cold-cathode and fluorescent lamp fill gas
- Mercury cell chlor-alkali plants (being phased out under Minamata)
- Dental amalgam restorations (Hg/Ag/Sn alloy)
- Reference fluid in McLeod gauges and old barometers
- Amalgamation in artisanal gold and silver recovery