Which best explains why the noble gases are chemically unreactive?

Question

anonymous · Answer

They have no valence electrons.

 They have the same number of protons and electrons.

 They have more neutrons than protons.

 They have very stable outer electron shells.

anonymous · Answer

those are the answers

mrnood · Answer

So - the middle two answers concern the structure of the atom - is there anything in those 2 that suggest why the elements might be very stable?

A valence electron is an electron in th eouter 'shell' of electrons. Is it possible for an atom to have NO valence electrons?

Would a stable outer shell indicate that the atom is not 'likely' to form chemical reactions with other atoms?