Noble Gases: Structure, Properties, and Uses

Group 18 definition and member elements

Group 18 of the periodic table is the set of low-reactive (historically “inert”) gases known as the noble gases. Its members are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and sometimes oganesson (Og). Under standard conditions, the first six are odorless, colorless, monatomic gases with very low chemical reactivity; oganesson’s properties are uncertain because it is unstable and only a few extremely short-lived atoms have been synthesized. Their low reactivity is explained by electron configuration: the valence shell is “full” (two electrons for helium; eight for the others), making the atoms very stable and unlikely to gain, lose, or share electrons. As a result, noble gases have weak interatomic forces (mainly London dispersion forces), leading to very low melting and boiling points and systematic trends down the group (increasing atomic size and intermolecular attractions). Only a few hundred noble gas compounds are known, with chemistry becoming more feasible for heavier members such as xenon, krypton, and argon.

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Inertness and electron configuration explanation

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