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Hg

Mercury

Mercury (Hg) is a transition metal with atomic number 80 and an atomic mass of 200.59. Its electron configuration is [Xe] 4f14 5d10 6s2.

Mercury key data

Symbol Hg
Atomic number 80
Atomic mass (standard atomic weight) 200.59
Molar mass 200.59 g/mol
Protons 80
Neutrons (most abundant isotope, mercury-202) 122
Electrons (neutral atom) 80
Category Transition metal
Period 6
Group 12
Block d-block
Noble gas notation [Xe] 4f14 5d10 6s2
Full electron configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2
Electrons per shell 2, 8, 18, 32, 18, 2

Atomic mass: IUPAC CIAAW abridged standard atomic weights, 2024. Most abundant isotope: NIST Atomic Weights and Isotopic Compositions.

The values are facts and free to use; this page’s selection and presentation are © 2026 ScienceQuest.

Measured properties of mercury

From PubChem, the US National Institutes of Health. Public domain. PubChem’s periodic table gives no value for the rows not shown.

Melting point 234.32 K (−38.83 °C), 92nd of 103 by melting point
Boiling point 629.88 K (356.73 °C), 79th of 93 by boiling point
Density 13.53 g/cm³, 14th of 96 by density
State at room temperature Liquid
Electronegativity 2 (Pauling), joint 31st of 95 by electronegativity
Van der Waals radius 209 pm, joint 48th of 99 by atomic radius
First ionisation energy 10.438 eV (1007.1 kJ/mol), 16th of 102 by first ionisation energy
Common oxidation states +2, +1
Discovered Ancient

Each rank counts down from the highest value, among the elements PubChem’s table gives one for, and links to that property ranked across the whole table. All of them are collected under periodic trends.

Mercury electron configuration

The full electron configuration of mercury is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2. With the noble-gas core collapsed it is [Xe] 4f14 5d10 6s2, and the outermost subshell is 6s2.

Bohr model of mercury (Hg): a nucleus and six shells holding 2, 8, 18, 32, 18 and 2 electrons from the inside out.
Bohr model of mercury (Hg). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.
Orbital box diagram of mercury (Hg), [Xe] 4f14 5d10 6s2, with the xenon core drawn as one bar: one box per orbital, filled by Hund’s rule, showing every orbital drawn holds a pair of electrons.
Orbital diagram of mercury (Hg). Image © ScienceQuest, CC BY 4.0: free to reuse with credit to ScienceQuest and a link to this page, as the image licence explains.

Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.

Mass of one mercury atom

A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.

Mass of one atom

  1. one atom = 200.59 / (6.02214076 × 10²³)
  2. = 3.3309 × 10⁻²² g

Atoms in one gram

  1. atoms per gram = 6.02214076 × 10²³ / 200.59
  2. = 3.0022 × 10²¹ atoms

Mercury on the periodic table

Mercury is in period 6, group 12, in the d-block.

The other elements of group 12 are zinc, cadmium and copernicium.

The rest of period 6

Work with mercury