Final answer:
Nitrogen needs to gain 3 electrons to achieve a noble-gas electron configuration.
Step-by-step explanation:
Nitrogen needs to gain 3 electrons in order to achieve a noble-gas electron configuration. This is because nitrogen has 5 valence electrons and needs a total of 8 to achieve stability, like the noble gas neon (which is in the same group as nitrogen). By gaining 3 electrons, nitrogen will have a total of 8 electrons in its outermost shell, achieving the desired electron configuration.