What does mercurous mean?
Mercurous is a technical adjective meaning “relating to mercury in the +1 oxidation state.” In this state, mercury occurs as the diatomic ion Hg₂²⁺, with each mercury atom having an average oxidation number of +1. Compounds described as mercurous include mercurous chloride, mercurous oxide, and mercurous iodide. The term is especially important in analytical and historical chemistry because many compounds containing mercury(I) differ in stability and reactivity from their mercury(II), or mercuric, counterparts. Modern usage has declined as the older naming convention has increasingly been replaced by explicit Roman-numeral oxidation-state notation, such as mercury(I) chloride. Nevertheless, mercurous remains an established term in specialized references and discussions of the historical use and chemistry of mercury compounds.
adjectiveDenoting or containing mercury in the +1 oxidation state, particularly in the form of the diatomic ion Hg₂²⁺. The adjective distinguishes these compounds from mercuric compounds, in which mercury has the +2 oxidation state.
- Relating to mercury in the +1 oxidation state or to compounds containing the Hg₂²⁺ ion.
"The pigment was historically prepared from finely divided mercurous chloride."
"Mercurous chloride was historically used as a medicinal and laboratory compound."
"The analyst used a gravimetric procedure to determine the mercurous content of the sample."
Mercurous means “mercury with a positive charge,” while mercuric means “mercury with a bigger positive charge.”
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does mercurous come from?
The word derives from Latin Mercurius, the Roman name associated with the god Mercury, messenger and patron of merchants and travellers; the same name was later applied to the planet and the element mercury. The adjective was formed in English with the suffix “-ous” to designate the lower oxidation state of the element.
How mercurous is actually used
This is a specialist chemical term, normally used in technical writing. The “-ous” ending here follows the traditional convention for the lower oxidation state and should not be interpreted as indicating the presence of free mercury.
Easily confused with mercurous
Mercurous denotes mercury in the +1 oxidation state, whereas mercuric denotes mercury in the +2 oxidation state.