Problem: Magnesium has three naturally occurring isotopes: 24 Mg (23.985 amu) with 78.99% abundance, 25 Mg (24.986 amu) with 10.00% abundance, and a third with 11.01% abundance.Look up the atomic weight of magnesium, and then calculate the mass of the third isotope.

FREE Expert Solution

We’re being asked to calculate the mass of the third isotope of magnesium. We can use the following equation:


Atomic Mass = [mass×f.a.]isotope 1+[mass×f.a.]isotope 2......



where atomic mass = average atomic mass of the element and f.a. = fractional abundance of the isotope. To get f.a., we simply need to divide the given percent abundance by 100.


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Problem Details

Magnesium has three naturally occurring isotopes: 24 Mg (23.985 amu) with 78.99% abundance, 25 Mg (24.986 amu) with 10.00% abundance, and a third with 11.01% abundance.

Look up the atomic weight of magnesium, and then calculate the mass of the third isotope.

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Isotopes concept. You can view video lessons to learn Isotopes. Or if you need more Isotopes practice, you can also practice Isotopes practice problems.

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