Quick answerMercury (Hg) is a transition metal with atomic number 80 and an atomic mass of 200.59 (2023), in group 12, period 6. It has been known since ancient times. It is used for fluorescent lamps and dental amalgam. Its electron configuration is [Xe] 4f14 5d10 6s2.
Mercury is the only metal that is liquid at room temperature, a silvery poison that once filled thermometers, barometers, and the felt hats of the Mad Hatter's trade. Today it still lights fluorescent lamps, fills some industrial switches, and, controversially, fills dental amalgam. Its vapour is toxic, so old mercury devices are being phased out worldwide under the Minamata Convention.
Key facts
| Symbol | Hg |
|---|---|
| Atomic number | 80 |
| Atomic mass | 200.59 (IUPAC standard atomic weight, 2023) |
| Category | transition metal |
| Group | 12 |
| Period | 6 |
| Block | d-block |
| Electron configuration | [Xe] 4f14 5d10 6s2 |
| Discovered | Known since ancient times |
| Uses | fluorescent lamps, dental amalgam, industrial switches and relays, barometers and thermometers, gold mining |
Overview
Mercury is the only metal that is liquid at room temperature, a silvery poison that once filled thermometers, barometers and the felt hats of the Mad Hatter's trade. It has atomic number 80, an atomic mass of 200.59, and the electron configuration [Xe] 4f14 5d10 6s2, and it sits in group 12, period 6 of the periodic table. It has been known since ancient times, mined as the red ore cinnabar, and no single discoverer is credited with it. Mercury's liquid form made it the natural choice for instruments: it rises and falls evenly in thermometers and barometers, and it conducts electricity in switches and relays. Today it still lights fluorescent lamps, fills some industrial switches, and, controversially, fills dental amalgam, the silver filling that has repaired teeth for over a century. Its vapour is toxic, and it builds up in fish as methylmercury, which is why pregnant women are advised to limit oily fish. Old mercury devices are being phased out worldwide under the Minamata Convention, named after the Japanese town poisoned by mercury waste, and mercury is now mined mainly in China.
Frequently asked questions
What is mercury used for?
Mercury is still used in fluorescent lamps, in some industrial switches and relays, and in dental amalgam, the silver filling that has repaired teeth for over a century. It once filled thermometers and barometers, because it is the only metal liquid at room temperature. Old mercury devices are being phased out under the Minamata Convention.
What is the symbol for mercury?
The chemical symbol for mercury is Hg, from its Latin name hydrargyrum, meaning liquid silver, rather than from the English word mercury. It has atomic number 80 and a standard atomic mass of 200.59, and it sits in group 12 and period 6. Mercury has been known since ancient times, so no single person discovered it.
What is the atomic number of mercury?
Mercury has atomic number 80, so it is the eightieth element in the periodic table. Its atom holds eighty protons and eighty electrons, and its standard atomic mass is 200.59. It is a transition metal in group 12 and period 6, with the electron configuration [Xe] 4f14 5d10 6s2, and it is the only metal liquid at room temperature.
Is mercury a metal?
Yes, mercury is a metal, a transition metal in group 12 of the periodic table. It is the only metal that is liquid at room temperature, a silvery fluid that flows and forms droplets. Its vapour is toxic, and it builds up in fish as methylmercury, which is why mercury devices are being phased out worldwide.
Is mercury poisonous?
Yes, mercury is poisonous. Its vapour can damage the nervous system, and it builds up in fish as methylmercury, which is why pregnant women are advised to limit oily fish. The Mad Hatter's trade once poisoned hat-makers who used mercury to make felt. Old mercury devices are being phased out under the Minamata Convention.
Quick quiz
Three questions from the facts on this page. No sign-up, no score is saved.
Keep exploring
- Periodic table — all 118 elements
- Hafnium (Hf) — another transition metal, atomic number 72
- Tantalum (Ta) — another transition metal, atomic number 73
- Tungsten (W) — another transition metal, atomic number 74
- Rhenium (Re) — another transition metal, atomic number 75
- Osmium (Os) — another transition metal, atomic number 76
- Iridium (Ir) — another transition metal, atomic number 77
- Platinum (Pt) — another transition metal, atomic number 78
- Gold (Au) — another transition metal, atomic number 79
- Rutherfordium (Rf) — another transition metal, atomic number 104
- Dubnium (Db) — another transition metal, atomic number 105
- All transition metal elements — on the periodic table
Sources & last updated
Last updated: . Figures are shown with their year; where sources disagree, the value is left out rather than estimated.