Topic summary
Mononuclidic
Extracted from the Wikipedia article Mononuclidic element.
Use in metrology
Mononuclidic elements are also of scientific importance because their atomic weights can be measured to high accuracy, since there is minimal uncertainty associated with the isotopic abundances present in a given sample. Another way of stating this, is that, for these elements, the standard atomic weight and (isotopic) atomic mass are the same.