• Various kinds of mercury
  • Merit/Demerit of mercury
  • Minamata convention
  • Laws and regulations  about mercury

Basic knowledge of mercury

What impression do you have of mercury? Do you consider it to be a typical hazardous material that is represented by Minamata disease? Or a substance that is familiar because it is widely used in daily life? Let us now explore some basic facts about mercury.


Physical properties

Atomic number80
Atomic weight200.59
Melting point -38.9°C/234.3K
Boiling point357°C/630K
Thermal conductivity7.8W/m·K
Specific gravity13.6g/cm3@273K
Vapor pressure0.16Pa@293K

Elemental mercury

Atomic symbolHg (derived from hydrargyrum in Latin, i.e. quicksilver in English)
Denotation mercury in English (derived from Mercury)

Periodic table of elements

Periodic table of elements (PDF: 178KB)

Properties of mercury

Mercury is a metal with the following three unique characteristics, and has been familiar and valuable to human beings since before BC.

  • The pressure of mercury vapor is rather high and it easily forms amalgams with other metals.
  • The melting point of mercury is below freezing point, which makes mercury the only metal that is liquid at room temperature and normal pressure.
  • The specific gravity of mercury is so large that iron floats on liquid mercury.

Types of mercury

Type Symbol of element Main use and characteristics Toxicity
Metal mercury   Hg Alkali industry; fluorescent tube; cold cathode fluorescent lamp (CCFL); blood-pressure meter; thermometer; rectifier; relay contact; gold mining using amalgamation; plating; dental filling material (also contained in petroleum, coal, natural gas, shale gas, etc.) May cause amalgam poisoning, or mercury poisoning through long-period inhalation of high concentration of mercury
Inorganic mercury Mercury sulfide HgS Cinnabar; pigment; paint; vermilion inkpad Not substantially toxic. Even when it enters a body, it is excreted in short time.
Mercury oxide HgO Mercury cell; germicide, preservative, medicine for conjunctivitis
Mercuric (i) chloride Hg2Cl2 Purgative; diuretic
Mercuric (ii) chloride HgCl2 Vinyl chloride manufacture; disinfectant Highly toxic
Organic mercury Alkyl mercury   The general term of organic mercury compounds that are composed of mercury bound with the alkyl group (CnH2n+1-) such as the methyl group (CH3-) and the ethyl group (C2H5-).  
(1) Methyl mercury CH3HgX Seed disinfectant, catalyst for acetylene derivatives.
(There are compounds such as methyl mercury chloride, methyl mercury bromide, methyl mercury hydroxide, methyl mercuric acetate, and methyl mercury nitrate.)
A toxin that is soluble in oil and is susceptible to biological accumulation. The main cause of Minamata disease.
High toxicity that affects the nerve center
(2) Dimethyl mercury C2H6Hg Toxicology test
Flammable liquid that is transparent and has slightly sweet odor
One of most toxic neurotoxins
(3) Sodium ethylmercurithiosalicylate C9H9HgNaO2S Preservative for vaccines.
Suspected as one of causes of autism.
Germicidal effect
(4) Diethyl mercury C4H10Hg Toxicology test
Colorless combustible liquid having slightly sweet odor.
One of causes of Minamata disease.
Extremely high neurotoxicity.
Phenylmercuric acetate CH3COOHgC6H5 Germicide for agricultural chemicals.
Currently agricultural use prohibited
Highly toxic. Causes kidney disorder when taken into human body.


  • YAMAMOTO, Yoshihiro. “Harukanaru Suigin no Tabi (Long Journey of Mercury)”, Sanbunsha
  • “Suigin (Mercury)”, The Chemical Society of Japan (ed.), Maruzen
  • IKUSHIMA, Kenji. “Suigin-shorigijyutsu ga Nihon no Enerugi-kiki o Sukuu (Mercury Treatment Technology Saves the Energy Crisis in Japan)”, CMC Publishing Co. Ltd.

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