Copper has two naturally occurring isotopes. Cu-63 has a mass of 62.939 amu and Cu-65 has a mass of 64.928 amu. Based on the atomic mass of copper, which isotope has a higher fractional abundance?
A) Cu-63
B) Cu-65
C) Cu-63 and Cu-65 have equal fractional abundances.
D) Insufficient data
E) Fractional abundance is independent of isotopes.

Question

Quizplus · Accepted Answer

The atomic mass of copper is the weighted average of the masses of its isotopes, taking into account their natural abundances. So, the higher fractional abundance would correspond to the isotope with the lower mass (Cu-63), which would contribute more to the overall atomic mass of copper. Therefore, Cu-63 has a higher fractional abundance.

Copper Has Two Naturally Occurring Isotopes