Why is the noble gas configuration inert?

[Cygnus X-1]

Walther Kossel and Gilbert Lewis:
"During the formation of a chemical bond, atoms combine together by gaining, losing or sharing electrons in such a way that they acquire nearest noble gas configuration."

By what understanding I have so far, and do correct me if I'm wrong, atoms tend to attain a state of greater "stability" by lowering potential energy, done by gaining, sharing, or losing electrons in order to attain the nearest noble gas configuration (having a "full valence shell"). What characteristic of noble gas configuration makes it a state of lower potential energy?

 

[drvrm]

By what understanding I have so far, and do correct me if I'm wrong, atoms tend to attain a state of greater "stability" by lowering potential energy, done by gaining, sharing, or losing electrons in order to attain the nearest noble gas configuration (having a "full valence shell"). What characteristic of noble gas configuration makes it a state of lower potential energy?

a completely filled valance shell designates lower energy and atoms tend to go to the lowest energy state ;
thats a fact corroborated by the ionisation energy for atoms with filled up shells are are higher than the unfilled ones.
the electrostatic potential energy is also lower as the nuclear charge is screened off by the electrons and for inert gases optimum screening is present ;
so naturally the atoms like to share charge of neighbours and try to attain the " filled up" shell configuration.

 

[Cygnus X-1]

the electrostatic potential energy is also lower as the nuclear charge is screened off by the electrons and for inert gases optimum screening is present ;
so naturally the atoms like to share charge of neighbours and try to attain the " filled up" shell configuration.

If one takes, for example, a lithium ion in lithium chloride, the lithium ion has lost an electron and thus has two electrons rather than the three it previously had. As lithium has three protons, how does having two electrons lower the electrostatic potential energy even though it has the electron configuration of helium?

Furthermore, is a minimal electrostatic potential energy the only thing that makes a full valence shell have a lower overall intra-atomic potential energy?

 

[DrDu]

The point is that the electrons in the valence shell do not screen each other well from the nuclear charge. So while the outer electron in Li sees approximately a nuclear charge of +1, the same electron will see an electric charge >+1 in the Cl- ion although the Cl atom is neutral. In addition the ions formed will attract each other. So basically the electrons tend to gather around the atom which has the highest number of valence electrons.