Nitrogen is present in group 15 of the periodic table.
The atomic number of nitrogen is 7 and has a mass number of 14.01u.
Thus in a neutral atom of nitrogen, there exist seven electrons.
Two electrons are located in the inner orbit, similar to the carbon electron configuration.
The remaining five electrons are distributed in the outer orbit.
Nitrogen ground-state electron configuration
- The outermost orbital has a capacity of eight electrons.
- The electronic configuration of nitrogen is 1s2 2s2 2p3.
- The 1S2 orbital is the innermost and has two stable electrons with the lowest energy.
- 2S2 orbital is in the outer shell but yet has two stable electrons.
- The nitrogen has a half-filled ‘P’ orbital, which is comparatively more stable.
- Thus the ‘p‘ orbital is the outermost shell.
- To achieve a stable gas configuration, nitrogen needs to have a fulfilled p orbital.
- The closest noble gas neon (Ne) has the electronic configuration 1s2 2s2 2p6.
Thus the nitrogen needs to get 3 more electrons.
Nitrogen can form 3 covalent bonds with another atom of nitrogen to get a ground-state electron configuration.
Thus sharing 3 electrons and completing the octet in both the atoms.
Configuration in different forms of nitrogen.
Elemental nitrogen (N2-gas)
Here, each atom of nitrogen is bonded to another atom via 3 bonds.
Thus a triple bond exists in this compound.
One ‘s’ and a single ‘2p’ orbital combine to form ‘2 sp’ orbitals.
One ‘sp’ orbital of nitrogen axially overlaps with the sp orbital of the other nitrogen to form a sigma bond.
The lone pair of each nitrogen is contained in the other sp orbitals.
There is a sideways overlap of p orbitals of nitrogen to form 2 pi bonds.
So, each nitrogen shares 3 electrons and fills its outer orbitals.
Thus it forms a linear structure that is sp hybridized.
The single 2s and the three 2p orbitals hybridize to give, sp3 orbitals.
- Three sp3 orbitals are used up in forming bonds.
- Each bonded sp3 orbital overlaps with the s orbital of the hydrogen atom, thus forming an N-H bond.
- The non-bonding sp3 orbital contains a lone pair of electrons.
- Thus nitrogen forms three bonds sharing three electrons with hydrogen.
- So it completes the octet, and the p orbital is filled.
- The hydrogen atoms also complete their duplet and fill their outer 1s orbital completely.
A tetrahedral structure is thus formed, and NH3 (ammonia) is sp3 hybridized.
Nitrosyl chloride (NOCl)
Here the central atom is nitrogen, and it is doubly bonded to one oxygen atom and singly bonded to one chlorine atom.
- Thus it shares three electrons and completes its outer shell.
- Here the nitrogen is sp2 hybridized, having a triangular planar structure.
- Three sp2 orbitals are present oxygen overlapping with one orbital, chlorine overlapping with another, and the last orbital occupied by electron lone pair.
- Nitrogen also forms a pi bond with the oxygen it is bonded to.