* Protons: 23 (This is the defining characteristic of vanadium, as the atomic number is the number of protons)

* Neutrons: The number of neutrons can vary, leading to different isotopes of vanadium. The most common isotope, vanadium-51, has 28 neutrons.

So, the nucleus of a vanadium-51 atom would have 23 protons and 28 neutrons.