# What is the molar mass of the isotope strontium-87 (""^(87) Sr)?

Is it not $87.0 \cdot g \cdot m o {l}^{-} 1$?
This site tells me that ""^87Sr is approx. 7.00% abundant. The molar mass quoted on the Periodic Table is $87.62 \cdot g \cdot m o {l}^{-} 1$. As always this molar mass is the weighted average of the individual isotopic masses. ""^88Sr, at approx. 83% abundance, is the major isotope.