Question

Xenon has an atomic number of $54$. A particular isotope of xenon has a mass number of $131$. How many protons and how many neutrons does each atom of that isotope have?

Answer 1

Xenon is a chemical element which is represented by the symbol $Xe$ and has the atomic number $54$. It is a colourless, dense and odourless noble gas found in the Earth’s atmosphere in very little amount. Xenon is in the group $18$ of the modern periodic table.

Complete answer:
The mass of an atom depends upon the number of particles in the nucleus. This includes the protons and the neutrons. The protons are the nuclear particles with unit positive charge whereas the neutrons are the fundamental neutral particles having zero electronic charges.
Now in this question, we have a Xenon element. The atomic number of the Xenon is $54$ thus it contains $54$ protons as we know that the atomic number of the element is equal to the number of protons present in the nucleus. As it is given that the mass number of Xenon is $131$ this number of neutrons in the nucleus of Xenon is $77$ as the mass number is the sum of the number of the protons and neutrons. This tells us that $^{131}Xe$ has $21\%$ isotopic abundance. As electrons have a negligible mass, so we will not consider the electronic mass for this problem.

Note:
The mass number which is also called an atomic mass number or nucleon number is the total number of neutrons and protons present in an atomic nucleus. The mass number of each different isotope of a chemical element is different.