Elements

Electron configuration of Mercury (Hg)

Read the Mercury electron configuration, noble-gas shorthand, valence shell, orbital filling logic, and the mistakes to avoid when writing Hg.

Guide: Guía práctica Read: 6 min Updated: 2026-06-21

Element guide

Electron configuration of Mercury (Hg)

The electron configuration of Mercury is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2. In shorthand form it is written as [Xe] 4f14 5d10 6s2.

Use this page to connect the notation with atomic number 80, the d-block, and the exceptional valence pattern of this unique liquid metal.

How to write the configuration

Configuration at a glance

Mercury has atomic number 80, so a neutral atom has 80 electrons. The configuration is a long one because mercury sits far down the periodic table. It includes a filled 4f subshell (14 electrons) and a filled 5d subshell (10 electrons), plus two electrons in the 6s orbital.

The shorthand [Xe] 4f14 5d10 6s2 compresses the 54 electrons of xenon's configuration plus the 24 more electrons in 4f, 5d, and 6s.

A fully filled d-subshell

Mercury has a completely filled 5d10 subshell, giving it unusual chemical behaviour. Along with zinc and cadmium, mercury completes group 12. The filled d-subshell means mercury has no d-electrons available for bonding, which contributes to its reluctance to form many compounds and its unique liquid state at room temperature.

Step-by-step filling walkthrough: 1. Start with atomic number 80. 2. Follow the Aufbau sequence through 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p. 3. Keep a running total: 2+2+6+2+6+2+10+6+2+10+6+2+14+10 = 80. 4. Write the noble-gas shorthand by replacing the filled core with xenon [Xe]. 5. Verify: add every superscript and confirm the total equals 80.

Relativistic effects and the liquid state

Mercury's unique properties come from relativistic effects. The 6s electrons move at a significant fraction of the speed of light near the mercury nucleus, causing the 6s orbital to contract and stabilise. This relativistic contraction makes the 6s2 pair exceptionally inert, explaining why mercury is liquid (weak metallic bonding) and why it shows a stable +1 oxidation state (Hg2 2+ dimer) in addition to Hg2+.

Real-world applications

  • Thermometers and barometers historically used mercury's uniform thermal expansion.
  • Fluorescent lamps contain mercury vapour that emits UV light when excited.
  • Dental amalgams use mercury's ability to form alloys with other metals.
  • Mercury is used in gold mining to form amalgams, though this practice is being phased out due to toxicity.

Common ions: Hg2 2+ (mercurous, losing one 6s electron per atom, dimeric) and Hg2+ (mercuric, losing both 6s electrons).

Mercury reference table

Item Value
Atomic number 80
Full configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2
Noble-gas notation [Xe] 4f14 5d10 6s2
Valence clue 6s2
Block d-block

Use the table as a learning reference, then verify advanced oxidation-state questions with your course material.

Before you submit an answer

  • The superscripts add up to 80 for a neutral Mercury atom.
  • The notation follows the filling order used in your course.
  • The last occupied subshell matches the periodic-table block.
  • Any transition-metal or actinide exception is checked against a reference.
  • The shorthand core is a noble gas, not a random previous element.

Common questions

What is the electron configuration of Mercury?

The neutral Mercury atom is written as 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2. The shorthand form is [Xe] 4f14 5d10 6s2.

How many valence electrons does Mercury have?

Mercury has two valence electrons in the 6s orbital (6s2). The filled 4f14 and 5d10 subshells are core levels and do not participate in typical bonding.

Why is Mercury liquid at room temperature?

Relativistic effects contract and stabilise the 6s2 pair, making the electrons less available for metallic bonding. Weaker metallic bonds mean mercury melts at a much lower temperature than its neighbours.

What oxidation states does Mercury show?

Mercury shows Hg2 2+ (mercurous, +1 oxidation state, a dimer with a Hg-Hg bond) and Hg2+ (mercuric, +2 oxidation state, losing both 6s electrons). The Hg2 2+ dimer is unique among group 12 elements.

Study notes and practice checks

Element-specific practice problems

Problem 1: Write the full electron configuration for neutral Mercury and verify the electron count against 80.

Problem 2: Convert the full configuration to noble-gas shorthand notation.

Problem 3: Compare the configuration of Mercury (Z=80) with Gold (Z=79) and Thallium (Z=81). How does the filling order explain the transition from 5d10 to 6p1?

Problem 4: Explain why Hg2 2+ (a dimer with a Hg-Hg bond) exists while Zn2 2+ and Cd2 2+ do not. How does the 4f14 filled subshell contribute?

Problem 5: Mercury is toxic, yet it was widely used in thermometers. How does its electron configuration relate to its chemical inertness and hence its historical usefulness?

Elena Marquez

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Elena Marquez

Chemistry educator and study-guide editor

Elena explains electron configurations, orbital diagrams, and periodic trends for learners who need clear steps before memorization. Her guides focus on counting, notation, and common classroom mistakes.

Credenciales: Editorial specialization in introductory chemistry, periodic trends, and student reference material.

Experiencia: More than eight years preparing practical chemistry explainers, worksheets, and reference material for independent learners.

Actualizado: 2026-06-21 Politica editorial Correcciones

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