Final answer:
Elements react to achieve a stable electron configuration like the noble gases. Noble gases such as helium, neon, and argon have full valence shells, meaning they don't typically participate in reactions. However, other elements prioritize gaining, losing, or sharing electrons to reach this stable configuration, leading to their reactivity.
Step-by-step explanation:
The reason that elements apart from noble gases are usually reactive is due to their electron configuration. Elements react to fill their valence shells (the outermost shell of an atom), achieving a stable electron configuration like that of noble gases. These gases, including helium, neon, argon, krypton, xenon, and radon, have full valence shells, making them generally unreactive.
However, it's important to note that noble gases can indeed form compounds under certain conditions. For instance, the three heaviest noble gases, argon, krypton, and xenon, can react with fluorine to form fluorides. The xenon fluorides are the best known, serving as the basis for other noble gas compounds. This shows that while the noble gases tend to be inert, they are not completely non-reactive.
On the other hand, the rest of the elements in the periodic table do not have completed outermost shells. Therefore, they can readily engage in chemical reactions to either gain, lose, or share electrons and achieve a full valence shell, hence exhibiting reactivity.
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