Noble gasses (group 8) or sometimes the inert gasesare are the least reactive elements in the periodic table because they have a full valence shell. They are not interested in loaning out or borrowing electrons and are very stable. The gases helium, neon, argon, krypton, xenon and radon make up the inert gases. Neon is the least reactive element on the periodic table. As a noble gas, neon is colorless and odorless with extremely low reactivity in its natural state.