Ionic compounds in the context of "Neon compounds"

Neon compounds are chemical compounds containing the element neon (Ne) with other molecules or elements from the periodic table. Compounds of the noble gas neon were believed not to exist, but there are now known to be molecular ions containing neon, as well as temporary excited neon-containing molecules called excimers. Several neutral neon molecules have also been predicted to be stable, but are yet to be discovered in nature. Neon has been shown to crystallize with other substances and form clathrates or Van der Waals solids.

Neon has a high first ionization potential of 21.564 eV, which is only exceeded by that of helium (24.587 eV), requiring too much energy to make stable ionic compounds. Neon's polarisability of 0.395 Å is the second lowest of any element (only helium's is more extreme). Low polarisability means there will be little tendency to link to other atoms. Neon has a Lewis basicity or proton affinity of 2.06 eV. Neon is theoretically less reactive than helium, making it the least reactive of all the elements.