Physical and Chemical Properties of Group 18 Elements Elements in Group 18 of the Periodic Table are: Helium, Neon, Argon, Krypton, Xenon, Radon These elements are known as noble gases. Physical properties of noble gases 1. Table shows some physical properties of Group 18 elements.Element Helium Neon Argon Krypton Xenon RadonProton … [Read more...] about Physical and Chemical Properties of Group 18 Elements