Kossel and Lewis in 1916 Developed the theory for the bond formation after watching the behavior of noble gases.
The noble gases were inert in behavior and do not react with any substance. Kossel and Lewis found that the Octateof noble gases was complete so they do not react.
They gave the theory that the elements react with other elements so as to complete their octet.
So according to this theory “atoms can combine either by transfer of valance electrons from one atom to another or by sharing of valence electrons in Order to have a complete octet or the configuration like the noble gases have in their valance shell”.
This is also known as Octet rule