SEARCH Articles Figures Tables Argon-helium systematics Group 18 . 5 Argon Helium Krypton Group 18 . 5 Argon Helium Krypton Neon Radon Xenon Neutral Compounds of Helium, Neon, and Argon Noble Gases Argon Ar, Helium He, Krypton Kr, Neon Ne, and Xenon Xe Polyatomic Ions of Helium, Neon, and Argon The Noble Gases Helium, Neon, Argon, Krypton, Xenon