Nonbonding Orbital
Definition and meaning of Nonbonding Orbital in chemistry.
A nonbonding orbital is a molecular orbital whose occupation by electrons neither increases nor decreases the bond order between the involved atoms. Its energy is typically identical to that of the original atomic orbitals from which it was derived.
In more detail
In molecular orbital theory, atomic orbitals combine to form bonding, antibonding, and nonbonding orbitals. When atomic orbitals have mismatched symmetries or significantly different energies, they do not interact effectively, resulting in nonbonding orbitals. Electrons residing in these orbitals are often localized on a single atom and correspond to lone pairs in Lewis structures. Because they do not contribute to the electron density between nuclei, they do not help hold the molecule together.
Key facts
| Field | Physical Chemistry |
|---|---|
| Bond Order Effect | Zero contribution |
| Equivalent Concept | Lone pairs in Lewis structures |
In the hydrogen fluoride (HF) molecule, the 2py and 2pz orbitals of fluorine do not have matching symmetry with the hydrogen 1s orbital, so they remain as nonbonding orbitals holding lone pairs.
Frequently asked questions
How do nonbonding orbitals affect bond order?
They have a bond order contribution of exactly zero, meaning they neither strengthen nor weaken the bond.
Where do nonbonding electrons reside?
They typically stay localized on the parent atom they originated from, acting as lone pairs.