The elements for which the neutral atom has a valence electron configuration of .
[tex]ns^2np^6[/tex]
are those whose valence electron shell has 2 + 6 = 8 electrons.
Those are the noble gases, except helium (He).
Here is the list of the noble gases and the configuration of their valence electron configuration:
He: [tex]1s^2[/tex]
Ne [tex]2s^22p^6[/tex]
Ar [tex]3s^23p^6[/tex]
Kr [tex]4s^24p^6[/tex]
Xe [tex]5s^25p^6[/tex]
Rn [tex]6s^26p^6[/tex]
Answer: Ne, Ar, Kr, Xe and Rn
