Share with your friends
Call

The mass of an atom depends on the number of massive particles. These include (i) the protons, fundamental nuclear particles with unit positive charge, and (ii), the neutrons, fundamental neutral particles with ZERO electronic charge.

Now we have elemental xenon, and thus we KNOW that the nucleus contains $"54 protons"$. If it didn't possess 54 protons it would not be elemental xenon, and would be some other element. And thus the is the sum of the massive nuclear particles: $54+77=131$, and hence the $""^131Xe$ isotope. tells me that $""^131Xe$ has 21% isotopic abundance.

Because electrons have to a first approximation negligible mass, we don't really have to consider electronic mass for this problem.

Talk Doctor Online in Bissoy App