Bonding background
8 valence electrons
6 bonding
2 nonbonding
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σ overlap of s orbitals
on adjacent atoms
π overlap of p orbitals
on adjacent atoms
6 bonding
2 nonbonding
Roll mouse over to see
σ overlap of s orbitals
on adjacent atoms
π overlap of p orbitals
on adjacent atoms
Lewis structures
This simple model based on electron-counting allows allocation of valence electrons as bonding or nonbonding. Lewis structures can be used to rationalize and predict molecular shape (VSEPR).
Valence bond model
Bonds result from overlap of s and p valence orbitals on adjacent atoms in
The model was modified to include use of hybrid orbitals (mixtures of s and p atomic orbitals) to rationalize composition and geometry of compounds of second-row elements (such as CH4 and BF3). Hybrid orbitals overlap in a σ fashion with other hybrid orbitals (or s or p orbitals) on adjacent atoms.
Molecular orbital theory
According to this more complete theory of bonding, electrons occupy molecular orbitals delocalized over the entire molecule. Because this is more complicated, we will only consider diatomic molecules.
This simple model based on electron-counting allows allocation of valence electrons as bonding or nonbonding. Lewis structures can be used to rationalize and predict molecular shape (VSEPR).
Valence bond model
Bonds result from overlap of s and p valence orbitals on adjacent atoms in
a σ fashion (end-on - bond density around bond axis)
Bonding electrons are localized around the bonded atoms.s with s, s with p, or p with p if both p orbitals lie on the bond axis
or a π fashion (side-on - bond density above and below bond axis)p with p if both p orbitals are perpendicular to bond axis
The model was modified to include use of hybrid orbitals (mixtures of s and p atomic orbitals) to rationalize composition and geometry of compounds of second-row elements (such as CH4 and BF3). Hybrid orbitals overlap in a σ fashion with other hybrid orbitals (or s or p orbitals) on adjacent atoms.
Molecular orbital theory
According to this more complete theory of bonding, electrons occupy molecular orbitals delocalized over the entire molecule. Because this is more complicated, we will only consider diatomic molecules.