When two nitrogen atoms bind to form the dinitrogen molecule, each atom provides 3 electrons to give the treble bond, and the remaining pair of electrons is a non-bonding lone pair, i.e. to give :N≡N: .
Covalent bonding in a molecule of ammonia: Each hydrogen atom needs one more electron to complete its valence energy shell. The nitrogen atom needs three more electrons to complete its valence energy shell. Therefore, three pairs of electrons must be shared between the four atoms involved.
Each hydrogen atom needs one more electron to complete its valence energy shell. The nitrogen atom needs three more electrons to complete its valence energy shell. Therefore three pairs of electrons must be shared between the four atoms involved. Three single covalent bonds will be formed.
Nitrogen molecule is formed by sharing of three electrons by each nitrogen, so total number of electrons shared are six.
Double and triple bonds
A nitrogen molecule is made up of two nitrogen atoms joined together. Nitrogen atoms can form three covalent bonds, so a triple bond forms between them. The structure of nitrogen is N≡N, showing that it has three shared pairs of electrons.