radical ion true MS This child of the former purgatory term ion chemical type was made obsolete. MS:1000376 OBSOLETE An ion, either a cation or anion, containing unpaired electrons in its ground state. The unpaired electron is denoted by a superscript dot alongside the superscript symbol for charge, such as for the molecular ion of a molecule M, that is, M+. Radical ions with more than one charge and/or more than one unpaired electron are denoted such as M(2+)(2). Unless the positions of the unpaired electron and charge can be associated with specific atoms, superscript charge designation should be placed before the superscript dot designation.