The noble gases are helium, neon, argon, krypton, xenon, radon, and ununoctium. The noble gases are relatively nonreactive. This is because they have a completevalence shell. They have little tendency to gain or lose electrons. These gases all have similar properties under standard conditions: they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).