What group of elements, found in group 18, is characterized by having eight valence electrons?

The group of elements found in group 18 is known as the noble gases. These elements are characterized by having a complete outer electron shell, which typically consists of eight valence electrons, except for helium, which has two. This stable electron configuration makes noble gases very unreactive or inert under normal conditions.

Noble gases such as helium, neon, argon, krypton, xenon, and radon exhibit very low chemical reactivity because they do not readily combine with other elements to achieve a more stable state. This is in contrast to other groups of elements, like the halogens, which have seven valence electrons and tend to react in order to gain one additional electron. Transition metals and alkaline-earth metals also have different valence electron configurations that do not lead to the unique stability seen in noble gases. Thus, the defining characteristic of group 18 elements is indeed their eight valence electrons, which contributes to their chemical stability.