The ions formed are $N^{3-}$, $O^{2-}$, $F^-$, and $Na^+$. All are isoelectronic with Neon ($10$ electrons). For isoelectronic species, the ionic radius increases as the nuclear charge (atomic number) decreases. Nitrogen has the lowest atomic number ($Z=7$), so $N^{3-}$ is the largest.