A nuclide is a specific isotope, which of course has specific Z_"the atomic number"Zthe atomic number, and a SPECIFIC number of neutrons. The sum of both these numbers is necessarily precise AND integral (why so?.. because we cannot have half a neutron or two thirds a proton, these are discrete fundamental particles).
On the other hand, the "relative atomic mass"relative atomic mass is the weighted average of the isotopic masses compared to the mass of a ""^12C12C isotope, whose nucleus contains 6 protons (necessarily, why so), and 6 neutrons.
By way of example, the element boron has Z=5Z=5, and has an isotopic distribution of 20% 20% ""^10B10B, and 80% 80% ""^11B11B, and their weighted average is 10.8110.81, which is the relative atomic mass, and the mass we would use if we calculated the formula mass of a boron-containing compound. And clearly this mass number CAN BE non-integral.
And so the "relative atomic mass"relative atomic mass is DIMENSIONLESS...and given the isotopic distribution common to most elements, it is NON-INTEGRAL. As a tip read the Periodic Table beside you now. This should be available in most exams of chemistry and fyziks, and a bit of study now will pay big dividends...
