Noble gases, rarely known as aerogens, make a group of chemical elements with 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 the radioactive radon (Rn).
The transuranic elements below are predicted to be noble gases. Ununoctium was formerly thought to be a noble gas but is now predicted to be a solid due to relativistic effects. In addition, flerovium seemed to exhibit noble-gas-like properties.