Here's how to determine the number of particles in the nucleus of a xenon atom:

* Atomic Number: Xenon (Xe) has an atomic number of 54. This means it has 54 protons in its nucleus.

* Mass Number: To find the number of neutrons, you'll need the mass number of the specific xenon isotope you're interested in. Xenon has multiple isotopes (atoms of the same element with different numbers of neutrons).

* For example, the most common isotope is xenon-132 (¹³²Xe). Its mass number is 132.

* Calculating Neutrons: To find the number of neutrons, subtract the atomic number from the mass number: 132 - 54 = 78 neutrons.

Therefore, the nucleus of a xenon-132 atom contains 54 protons and 78 neutrons, for a total of 132 particles.

Key Point: The number of particles in the nucleus (protons and neutrons) can vary depending on the isotope of xenon you are considering.