when main group elements react, they tend to acquire eight outer-shell electrons (ns2np6). this is called an octet, and it is a particularly stable configuration. group valence to attain octet 1a ns1 lose one electron 2a ns2 lose two electrons 3a ns2np1 lose three electrons 5a ns2np3 gain three electrons 6a ns2np4 gain two electrons 7a ns2np5 gain one electron 8a ns2np6 rarely gain or lose electrons nonmetals in the third period and beyond can break the octet rule because they have vacant d orbitals that allow them to accommodate more than eight outer-shell electrons. part a if the following elements were to form an ionic compound, which noble-gas configuration would they most likely attain? drag the appropriate elements to their respective bins.