INERT GASES(NOBLE GASES):- The 18th group elements are called Inert gases or Noble gases. He, Ne, Ar, Kr, Xe belongs to this group.
They are called inert gases because they are chemically inert normally they don't participate in any chemical reaction. It is due to their electronic configuration.Helium has completed duplet(2 valence electrons),other elements have completed their octet(8 valence electrons).Hence their electronic configuration is stable.
SOME PROPERTIES OF INERT GASES(NOBLE GASES):-
1)Their valence electrons are eight except He has 2.
2)They have completed their octet except He which completed duplet.
3)all of them are gases at room temperature.
4) They are non-reactive.
5) These gases are rarely available but very useful, so they are Noble gases.