Why Noble gases inert in nature?

Noble gases are inert in nature because they have a full complement of electrons in their outermost electron shell, which is also known as the valence shell. This makes them highly stable and unreactive under normal conditions. The stability of noble gases is primarily due to the following factors:

Full electron configuration: Noble gases, such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn), have completely filled electron shells. For example, helium has two electrons in its first (and only) electron shell, while neon has eight electrons in its second electron shell. This full complement of electrons gives them a stable electron configuration similar to that of the nearest noble gas in the periodic table.

Minimal electron affinity: Noble gases have a low tendency to gain or lose electrons because their electron shells are already full. In chemical reactions, atoms typically strive to achieve a stable electron configuration by either gaining, losing, or sharing electrons with other atoms. Noble gases do not need to do this because their electron configurations are already stable.

Lack of unpaired electrons: Noble gases lack unpaired electrons in their outermost electron shell. Unpaired electrons are more likely to participate in chemical reactions, but noble gases have all of their electrons paired, which reduces their reactivity.

Due to their inert nature, noble gases are often used in various applications where their lack of reactivity is advantageous. For example:

Helium is used in balloons and airships because it is lighter than air and does not combust.
Argon is used in welding to create an inert atmosphere that prevents the oxidation of metals during the welding process.
Neon is used in neon signs and lighting because it emits a bright, colorful glow when electrically stimulated.
Xenon is used in certain types of lamps, including car headlights and photographic flashes, for its intense, white light.
While noble gases are generally unreactive, they can be made to form compounds under extreme conditions, such as high pressure and temperature, or in the presence of highly reactive elements. However, these conditions are not encountered in typical, everyday environments.