State why noble gases have stable electronic configuration while atoms of other elements have unstable electronic configuration.

Octet and duplet structures seem to represent stability and are said to be stable electronic configuration.

Noble gases have their outermost or valence shell complete i.e., they have 2 electrons in outermost shell e.g., helium [electronic configuration 2] or they have 8 electrons in outermost shell e.g., neon [electronic configuration 2,8] or argon [electronic configuration 2,8,8 ]. Hence, they have stable electronic configuration. They do not gain, lose or share electrons and are unreactive or inert.

Atoms of other elements have incomplete valence shell, hence they have unstable electronic configuration. So, they can gain, lose or share electrons to attain the stable electronic configuration of the nearest noble gas.