Answer: INERTGAS

AnswerCrossword Clue
INERTGASKrypton, in science
INERTGASHe is one
INERTGASIt won't react well
INERTGASItem in the periodic table's last column
INERTGASHelium, e.g.
INERTGASXenon, for one
INERTGASIt's hard to get a reaction out of it
INERTGASNoble thing
INERTGASNeon or helium
INERTGASNeon or xenon.
INERTGASItem in Group 8A of the periodic table
INERTGASKrypton or xenon
INERTGASHelium, for one
INERTGASKrypton, e.g.
INERTGASOne won't react under normal circumstances
INERTGASMolecular nitrogen, e.g.
INERTGASRadon, e.g.
INERTGASHelium or krypton
INERTGASNeon or xenon
INERTGASNeon, for one
INERTGASHelium or neon
INERTGASKrypton, for one