Nitrogen and oxygen primarily form a covalent bond when they combine. This is due to the nature of both elements and their electron configurations. Nitrogen has five electrons in its outer shell, while oxygen has six. To achieve a stable electron configuration, both atoms prefer to share electrons rather than transfer them completely, which is typical of ionic bonds.
When nitrogen and oxygen bond, they share electrons in order to fill their respective valence shells. This sharing leads to the formation of a molecule, typically represented as NO (nitric oxide) or NO2 (nitrogen dioxide), depending on the context. The bond between these two elements is characterized by a degree of polarity due to the difference in their electronegativities, but fundamentally, it is a covalent bond rather than an ionic one.