Element charge lookup

What Is the Charge of Mercury?

Mercury commonly forms Hg+ Hg2+ in introductory ionic compounds.

Mercury has two faces: ordinary mercury(II), Hg2+ (HgCl2, HgS — the crimson pigment vermilion), and the peculiar mercury(I), which is never a lone Hg+ but always the dimer Hg2 2+ — two mercury atoms holding hands, sharing a +2 charge, as in calomel Hg2Cl2.

Element	Mercury
Symbol	Hg
Atomic number	80
Common ionic charge	+1, +2
Common ions	Hg+, Hg2+

Visual reference

Mercury element image and atomic model

Images are used as visual references; charge rules still depend on the compound.

Mercury element sample — **Mercury sample image**Hi-Res Images of Chemical Elements, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/mercury.phpOriginal image source

**Mercury Bohr model**Atomic model image from the open Periodic-Table-JSON dataset. It is a simplified electron-shell reference, not a scale drawing.Original Bohr model source

Where Mercury's charge options come from

Mercury is [Xe]4f14 5d10 6s2, its 6s pair relativistically clenched — the grip so strong that mercury atoms barely bond each other, leaving the metal liquid. Losing both 6s electrons gives Hg2+; losing one per atom is only viable if two ions share a covalent Hg–Hg bond, hence the unique stable diatomic cation Hg2 2+.

This is a classroom reference range, not an exhaustive list of all oxidation states.

The trap in Mercury problems

Writing mercury(I) chloride as HgCl. The numeral I refers to +1 per mercury, but the real species is Hg2 2+, so calomel is Hg2Cl2 — the formula every general-chemistry exam loves to catch students on.

Worked example: Hg in a formula problem

Name Hg2Cl2 and HgCl2, and note the danger difference.

Hg2Cl2 is mercury(I) chloride (calomel), insoluble and once used in medicine; HgCl2 is mercury(II) chloride, soluble and violently toxic ('corrosive sublimate'). One charge state apart, historically the difference between remedy and poison.

Hg+ and Hg2+ in real compounds

HgCl

Mercury chloride

Hg+ balances chloride ions.

Hg2O

Mercury oxide

Mercury can form oxides where total positive and negative charge balances.

Questions students ask about mercury

What charge is the mercury in old thermometers?

Zero — liquid metal, atoms uncharged. The vapor those atoms shed is the neutral-atom hazard; the ionic hazards (Hg2+ and methylmercury) arise after environmental conversion.

What is methylmercury's charge story?

Microbes attach CH3- to Hg2+, making CH3Hg+ — a +1 organometallic ion fat-soluble enough to climb food chains into tuna. The charge is why it binds protein sulfurs; the methyl is why it reaches your nervous system.

How do I verify mercury(I) is really a dimer?

Classic evidence: calomel solutions are diamagnetic (a lone Hg+ would have an unpaired electron and be magnetic), and X-ray structures show the Hg–Hg bond outright. A tidy case of formulas following measurement.

How do I use this charge in formulas?

Combine positive and negative ions so the total charge is zero — or let the ionic compound calculator do the crossing for you. The full chart lives on the periodic table with charges.

Where this data comes from

Charges and element facts on this page are checked against the primary references below. Found an error? Email hello@periodictablewithcharges.com — corrections ship in the next content update. See how this site is edited.

PubChem Periodic Table

Used as a reference source for element identity and chemistry context.

Royal Society of Chemistry Periodic Table

Used as a reference source for element identity and chemistry context.

Neighbors of Hg on the table

Zinc chargeZn: +2 Cadmium chargeCd: +2 Dysprosium chargeDy: +3 Cesium chargeCs: +1 Barium chargeBa: +2