Valence Bond Theory
Definition and meaning of Valence Bond Theory in chemistry.
Valence bond theory is a quantum mechanical model explaining chemical bonding by the direct spatial overlap of half-filled atomic orbitals from different interacting atoms.
In more detail
According to this fundamental theory, a covalent bond successfully forms when two atoms approach each other closely enough that their valence electron orbitals occupy the exact same physical space, allowing them to share a pair of electrons with mutually opposite spins. The overall strength of the resulting chemical bond depends heavily on the extent of the orbital overlap, with greater spatial overlap leading to a more stable and stronger bond. The theory also heavily utilizes the mathematical concept of orbital hybridization to accurately explain and predict the observed three-dimensional geometries of polyatomic molecules that cannot be described by simple overlapping atomic orbitals alone.
Key facts
| Field | General Chemistry |
|---|---|
| Core Mechanism | Atomic orbital overlap and electron pairing |
| Key Concept | Orbital hybridization |
In a basic hydrogen molecule (H2), the valence bond theory clearly describes the single chemical bond as the direct head-on overlap of the two spherical 1s atomic orbitals from each constituent hydrogen atom.
Frequently asked questions
How exactly does valence bond theory differ from molecular orbital theory?
Valence bond theory closely focuses on localized bonds formed by specifically overlapping individual atomic orbitals, whereas molecular orbital theory considers bonding electrons as being mathematically delocalized over the entire molecule.