Mercury

Mercury (chemical symbol Hg) is a liquid metallic element that historically was used in many medicines, but is now restricted due to legitimate concerns about mercury poisoning which is primarily found in seafood.

Chemistry

Basic chemistry

Mercury is a silvery liquid at standard temperature and pressure. It has the atomic number 80 and an atomic weight of 200.592.

Radiochemistry

Mercury exists in multiple stable isotopes on earth; mercury-202 is the most abundant, forming 29.7%, mercury-200 accounts for another 23.1%. Mercury-199, mercury-201, and mercury-198, account for 16.9%, 13.1%, and 10% respectively. Mercury-204 forms 6.8% of the total. Many other radioactive mercury isotopes are known, many with very short half-lives .

Toxicity

Unfortunately mercury demonstrates marked toxicity, see main article on mercury poisoning. The prototypical condition of mercury toxicity is Minamata disease.

Medical importance

• mercury has been a key ingredient for dental amalgam for many years, the elemental mercury is alloyed with other metals including silver, tin, copper, and occasionally zinc. It forms a silvery paste which is used to fill the carious cavity, which then sets to form a hard permanent dental filling.
• thimerosal, an organomercury antiseptic agent was for decades used as the main preservative in vaccines, but has now been largely phased out due to concerns about its toxicity
  • thimerosal is still used as a topical antiseptic for some applications

Radiological importance

• mercury-197 and mercury-203 were historically used as radiotracers in renal imaging

History and etymology

Mercury has been known about since prehistoric times. It was named quicksilver by Aristotle (384-322 BCE) and liquid silver by Dioscorides (40-90 CE) .

Historically mercury was a popular treatment for sexually-transmitted infections, in particular syphilis, but was abandoned many years ago due to mercury's inherent toxicity .