>>14151975The electrons are what makes a noble gas noble. The electrons are all happy, and so don't do much chemically.
It's the protons and neutrons that make a radioactive element radioactive. If there's too many protons or neutrons, then the nucleus of the atom will decay. Keep in mind though, that the nucleus is separate from the electrons - the chemistry of an element has little to no connection to it's radioactivity.
