The some of the element of the 18^th group of the periodic table which do not combine with other elements. Those elements of the 18^th group are helium, neon, argon, krypton, xenon and radon. These elements of the 18^th group is known as the noble gas or inert gas and this is because of the reason that they do not react at all. If we look at the electronic configuration of noble gases, we would notice that except helium, all other inert gases have 8 electrons (helium has 2) in their outermost shells. This is considered to be the most stable arrangement of electrons.