Mercury (Hg)
Mercury is element 80, a transition metal in group 12, period 6. A neutral atom has 80 protons, 121 neutrons and 80 electrons, 2 of them valence electrons.
Transition metal- Atomic number
- 80
- Atomic mass
- 200.59 u
- Valence electrons
- 2*
- Protons · neutrons
- 80 · 121
- Electrons per shell
- 2, 8, 18, 32, 18, 2
- At room temperature
- liquid
Bohr model of mercury
The Bohr model draws mercury as a nucleus of 80 protons and 121 neutrons, with its 80 electrons on 6 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 18 in shell 5, 2 in shell 6. Press Build the atom to watch the shells fill from the inside out. The outer ring (the P shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of mercury
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰
Short form (noble gas notation): [Xe] 6s² 4f¹⁴ 5d¹⁰. The [Xe] stands for the electrons of xenon, the noble gas before it.
How many valence electrons does mercury have?
Mercury has 2 valence electrons.
Mercury is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 2 electrons in its outermost shell (shell 6), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 80 | equal to the atomic number |
|---|---|---|
| Electrons | 80 | equal to the protons in a neutral atom |
| Neutrons | 121 | mass number 201 − 80 protons |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Mercury properties
| Symbol | Hg |
|---|---|
| Category | Transition metal |
| Group · period · block | 12 · 6 · d |
| Atomic mass | 200.59 u |
| State at 25 °C | liquid |
| Melting point | 234.3 K (-38.8 °C, -37.9 °F) |
| Boiling point | 629.9 K (357 °C, 674 °F) |
| Density | 13.5336 g/cm³ |
| Electronegativity (Pauling) | 2 |
| Atomic radius | 209 pm |
| First ionization energy | 10.438 eV |
| Electron affinity | — |
| Oxidation states | +2, +1 |
| Common ion charge | +2, +1 |
| Discovered | Known since ancient times |
Where mercury sits on the periodic table
Group 12: Zinc, Cadmium, Copernicium.
Questions about mercury
How many valence electrons does mercury have?
Mercury has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does mercury have?
A neutral mercury atom has 80 protons and 80 electrons. Its most common form has about 121 neutrons (mass number 201 − 80 protons).
What is the electron configuration of mercury?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰, written in short form as [Xe] 6s² 4f¹⁴ 5d¹⁰.
What does the Bohr model of mercury look like?
A nucleus of 80 protons and 121 neutrons, circled by 6 electron shells holding 2, 8, 18, 32, 18, 2 electrons.
What is the atomic number of mercury?
80. The atomic number is the number of protons in the nucleus, and it is what makes an atom mercury.