Answer:
They have in common that they form molecules by covalent bonds.
Step-by-step explanation:
The covalent bond is the chemical bond between two atoms where electrons are shared, forming a molecule.
Covalent bonds are established between non-metallic elements, such as hydrogen H, oxygen O and nitrogen N in this case.
Atoms that bind to the bond must be able to gain electrons and there is a small electronegativity between the atoms. You should keep in mind that the valence electrons are those found in the last layer of the atom and are the only ones that are willing to be shared with another atom. In addition, when two atoms are joined they always comply with the octet rule, that is, they tend to complete their last energy levels (layers) with an amount of 8 electrons and be stable.
Another characteristic of covalent union is that each electron of the pair that has been shared is attracted by the nuclei of the two atoms.