Isotopomeric ion true OBSOLETE Isomeric ion having the same numbers of each isotopic atom but differing in their positions. Isotopomeric ions can be either configurational isomers in which two atomic isotopes exchange positions or isotopic stereoisomers. The term isotopomer is a shortening of isotopic isomer. MS:1000367 This child of the former purgatory term ion chemical type was made obsolete. MS