Final answer:
The noble gases are not the only elements that can exist in a monoatomic state; however, they are distinct in being unreactive and monoatomic at room temperature and pressure.
Step-by-step explanation:
While it is true that the noble gases (helium, neon, argon, krypton, xenon, and radon) are unreactive and monoatomic at room temperature and pressure, they are not the only elements that can be found in a monoatomic form. Other elements can exist in a monoatomic state under certain conditions, although this is not their standard state at room temperature and pressure.
Noble gases earned their "noble" moniker due to their full valence electron shells, which render them chemically inert under most circumstances. Interestingly, though considered inert for many years, it was discovered in 1962 that noble gases can form chemical compounds under special conditions.