Of the 80 elements with at least one stable isotope, 26 have only one stable isotope, and the mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element.
26 have only one stable isotope. This is of the 80 elements with at least one stable isotope. The mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element. This is of the 80 elements with at least one stable isotope.