Q.Explain why the noble gases show very low chemical reactivity in general, and why xenon in particular is able to form a genuine chemistry of compounds.

[!TLDR] Noble gases have a complete octet so they have no inherent drive to bond; xenon forms compounds because it is comparatively large with a comparatively low ionisation enthalpy, letting a strongly electronegative partner like fluorine pull electron density from it. [!ANSWER] Noble gases are unreactive because their valence shell is already full …

Every noble gas (except helium, with a full $1s^2$ shell) has the outer configuration $ns^2np^6$ -- a completely filled valence shell. Because chemical bonding is fundamentally driven by atoms gaining, losing or sharing electrons to reach a more stable, complete electron configuration, an atom that already has a complete octet has essentially no inherent tendency either to gain or lose electrons, and consequently very little tendency to form ordinary covalent or ionic bonds -- this is the structural root of the noble gases' celebrated chemical inertness. Xenon, however, is an exception among the practically available noble gases (radon is too radioactive to study conveniently) for two related reasons: it is the largest and most polarisable of the readily available noble gases, so its outermost electrons are held comparatively loosely, and it has the lowest first ionisation enthalpy of the group's stable members. This ionisation enthalpy, though still very high by the standards of the periodic table generally, is low enough that an extremely electronegative, strongly oxidising partner -- above all fluorine, the most electronegative element there is -- can pull sufficien …

Explain inertness from the complete-octet configuration, then identify xenon's two distinguishing properties (large size, comparati …

Claiming noble gases NEVER react (xenon's real, isolable compounds are the whole point of this section); forgetting that heli …