The only naturally occurring isotopes of nitrogen are N-14 and N-15. Based on the atomic mass of the element nitrogen on the Periodic Table, compare the relative abundances of the naturally occurring isotopes of nitrogen

Isotope N–14 = 99%

Isotope N–15 = 1%

Explanation:

Let isotope A be N-14

Let isotope B be N-15

From the question given above, the following data were obtained:

For isotope A (N-14):

Mass of A = 14

Abundance of A = A%

For isotope B (N-15):

Mass of B = 15

Abundance of B = (100 – A%)%

Atomic mass of nitrogen = 14.01 amu

Thus, we can obtain the relative abundances of the naturally occurring isotopes of nitrogen as illustrated below:

Atomic mass = [(Mass of A × A%)/100] + [(Mass of B × B%)/100]

14.01 = [(14 × A%)/100] + [(15 × (100 – A%)/100]

14.01 = 0.14A% + 0.15(100 – A%)

14.01 = 0.14A% + 15 – 0.15A%

Collect like terms

14.01 – 15 = 0.14A% – 0.15A%

– 0.99 = – 0.01A%

Divide both side by – 0.01

A% = – 0.99 / –0.01

A% = 99%

Abundance of B = (100 – A%)%

Abundance of B = (100 – 99)%

Abundance of B = 1%

Thus, the relative abundances of the naturally occurring isotopes of nitrogen are:

Isotope N–14 = 99%

Isotope N–15 = 1%

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