Why is mercury a liquid at room temperature?

Mercury's liquid state at room temperature is largely a consequence of relativistic effects. The 6s electrons in Hg travel fast enough that their relativistic mass increase contracts and stabilises the 6s orbital, weakening metallic bonding. The result is a very low melting point (−38.83 °C) compared to neighbouring heavy metals, leaving mercury liquid across a wide everyday temperature range.

Why does Mercury have the symbol Hg?

The symbol Hg comes from the Latin "Hydrargyrum," meaning liquid silver (from Greek hydrargyros: hydor = water, argyros = silver). The element has been known since antiquity under names referencing its liquid, silvery appearance.

How toxic is mercury?

Mercury and many of its compounds are highly toxic. Elemental mercury vapour is rapidly absorbed through the lungs and is a potent neurotoxin. Organic mercury species — especially methylmercury — bioaccumulate in the food chain and cause severe neurological damage (Minamata disease). Inorganic mercury salts damage the kidneys. Handling requires strict controls; thermometers, switches, and other mercury-containing items must be disposed of as hazardous waste.

What are mercury's main modern uses?

Despite heavy restrictions, mercury is still used in fluorescent and CFL lamps (small sealed amounts produce UV radiation), dental amalgam fillings (silver–tin–mercury alloy), some specialty electrical switches and relays, gold and silver artisanal mining (amalgamation), laboratory instruments (manometers, tilt switches), and skin-lightening cosmetics (now illegal in many jurisdictions).

What oxidation states does mercury commonly show?

Mercury has two main oxidation states: Hg⁺ (+1), which exists almost exclusively as the diatomic mercurous ion Hg₂²⁺ (e.g., Hg₂Cl₂, calomel), and Hg²⁺ (+2), which forms a wide range of mercuric compounds such as HgCl₂ (corrosive sublimate) and HgO. The 0 oxidation state occurs in the liquid metal itself.

How many stable isotopes does mercury have?

Mercury has seven stable naturally occurring isotopes: Hg-196, Hg-198, Hg-199, Hg-200, Hg-201, Hg-202, and Hg-204. Hg-202 is the most abundant at 29.86%. This isotopic diversity makes mercury useful in isotope-ratio studies and environmental tracing.

Mercury Element Properties

Look up every key property of Mercury (Hg, Z=80) — from atomic mass and electron configuration to melting point, toxicity, and industrial uses.

Toxicity Warning. Mercury and its compounds are highly toxic. Elemental mercury vapour causes irreversible neurological damage. Methylmercury bioaccumulates in the food chain (Minamata disease). Mercury-containing items must be handled and disposed of as hazardous waste. Do not break mercury thermometers or fluorescent bulbs indoors.

Hg 80

Mercury (Hydrargyrum)

Atomic number 80 · Group 12 · Period 6 · Post-Transition Metal

The only metal that is liquid at room temperature — known since antiquity for its silvery, flowing appearance and extreme density.

Copied!

Identity & Classification

Atomic Structure

Physical Properties

Thermodynamic Properties

Chemical Properties

Notable Isotopes

Click any value to copy it to the clipboard.

Summary

Mercury (symbol Hg, atomic number 80) is the only metallic element that is liquid at standard room temperature and pressure. A heavy post-transition metal in Group 12, Period 6, mercury has been known since antiquity and was central to early alchemy, medicine, and metallurgy. Its distinctive liquid silvery appearance, high density (13.534 g/cm³), and ability to form amalgams with most metals made it invaluable for centuries. Today its use is heavily restricted due to significant neurotoxicity and environmental persistence. Modern applications include fluorescent lighting, specialty electronics, dental amalgams, and scientific instruments. This reference card consolidates its atomic, physical, chemical, electronic, and thermodynamic properties in a single searchable view.

How it works

The page loads a complete, curated dataset of Mercury (Hg) properties.
Properties are grouped into thematic sections: identity, atomic structure, physical, thermodynamic, and chemical.
Use the search box to filter any property by name or value.
Click any value to copy it to the clipboard.
Notable isotopes are listed with abundance and half-life data.
A prominent toxicity warning summarises the health and environmental hazards of mercury.

Use cases

Quick reference during chemistry homework or exams.
Verify data for lab reports or research papers.
Compare Mercury with neighboring elements (Cd, Tl, Au).
Study periodic trends — atomic radius, ionization energy, electronegativity across Period 6.
Understand why mercury is liquid at room temperature (relativistic effects).
Teaching hazardous-substance awareness and toxicology fundamentals.
Research on fluorescent lamps, amalgam dentistry, or mercury remediation.
Environmental science studies on bioaccumulation and methylmercury hazards.

Frequently Asked Questions

Last updated: 2026-06-02 · Reviewed by Nham Vu