Bohr-Bury model also refer as octet rule. It states that the atom always tends to have eight electron in its outer most orbit. And in order to complete their octet atoms lose, share or gain their outer most electron to other atom. This rule also gives us the principle for electronic configuration inside an atom. According to this rule maximum number of electrons that can be accommodate in a shell or orbit is given by ” 2n2 “. where n is the shell number.