Question

Do all of the molecules obey the octet rule? If not, why? did the octet rule fail?

Answer 1

The majority do. The exception is the earth metals that when bonding form an electron cloud rather then sharing their valence electrons.

Answer 2

no all molecules do not obey octet rule. most molecule do so it has been considered as a general rule. but there are exceptions like H2 , BF3 ,SF6 ..but then chemistry is always about exceptions isn't it?