Names for muonium and hydrogen atoms and their ions - (IUPAC recommendations 2001)

Muons are short-lived species with an elementary positive or negative charge and a mass 207 times that of the electron. These recommendations concern positive muons, given the short lifetime of negative muons. A positive muon mimics a light hydrogen nucleus, and names are given in analogy to existing names for hydrogen-containing compounds. A particle consisting of a positive muon and an electron (mu (+)e(-)) is named "muonium" and has the symbol Mu, Examples:''muonium chloride,'' MuCl, is the equivalent of deuterium chloride, (HCl)-H-2 or DCl; "muoniomethane":, CW:Mu. is the product of the muoniation of methane; and NaMu is "sodium muonide."