Chemistry

The key here is molecular orbital (MO) theory — you need to build up the electron configuration by filling orbitals in order of increasing energy, just like you would for atoms. Start by counting total valence electrons (remember the extra electron from the negative charge), then fill the MO diagram for diatomic nitrogen, paying careful attention to which orbitals are antibonding (marked with $^*$). Only electrons in those antibonding orbitals count toward your answer.

The key here is molecular orbital (MO) theory — you need to build up the electron configuration by filling orbitals in order of increasing energy, just like you would for atoms. Start by counting total valence electrons (remember the extra electron from the negative charge), then fill the MO diagram for diatomic nitrogen, paying careful attention to which orbitals are antibonding (marked with $^*$). Only electrons in those antibonding orbitals count toward your answer.