What is the most characteristic property of the noble gases?

The most characteristic property of the noble gases is their extremely low chemical reactivity as compared to other elements. The noble gases all have a full set of electrons in their outer shells, so they have little tendency to trade electrons with other elements to form compounds.

The six naturally occurring noble gases are helium, neon, argon, krypton, xenon and radon. They are sometimes called the inert gases and are located on the right end of the periodic table in Group VIII.

In addition to being nonreactive, the noble gases have high ionization energy, a low boiling point and negligible electronegativity. They exist as odorless, colorless, monatomic gases under normal conditions.