The diatomic molecule that is formed when two atoms share six electrons is N2.
The atomic number of nitrogen is 7 and its electronic configuration is 2,5. This implies that, nitrogen has 5 electrons in its outermost shell. To attain the octet structure, it needs 3 electrons more. To form a diatomic molecule, two nitrogen atoms come together and each donate three electrons, which are equally shared between the two, thus, each ends up having 8 electrons in its outermost shell.
