What is the electronic theory of chemical bonding?

(N/A) The electronic theory of chemical bonding,developed by Kossel and Lewis in $1916$,explains how atoms combine to form chemical bonds.
$1$. Octet Rule: Atoms tend to combine by transferring valence electrons (gaining or losing) or by sharing valence electrons to achieve a stable octet ($8$ electrons) in their outermost shell.
$2$. Chemical Combination: This theory proposes that atoms achieve stability by attaining the noble gas configuration through the formation of ionic or covalent bonds.
$3$. Limitations: The theory does not explain the stability of molecules with expanded octets (e.g.,$PF_5$,where $P$ has $10$ electrons) or incomplete octets (e.g.,$BF_3$).