The element of which group are nonreactive?

If we look closely at the periodic table under the elements that are non metal, we could see a pattern. There’s an outer shell that will eventually equal to eight. The octet rule determines how many electrons and protons are going to be surrounded by the nucleus (neutrons) each time we go down the group. The atomic number will increase along with It’s electron configuration so an additional shell would be included. Those are referred to noble gases because they’re non reactive.

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts