# What is the isotopic composition of strontium metal?

This site reports the isotopic composition of strontium as ""^84Sr, 0.56%; ""^86Sr, 9.86%;""^87Sr, 7.00%;""^88Sr, 82.58%. The weighted average of the isotopes in $87.62 \left(1\right) \cdot \text{amu}$. The quoted atomic mass should be near to the weighted average of the isotopes.
Since for strontium, $Z = 38$, there are 84-38=??*"neutrons" in the ""^84Sr isotope.