Chapter 9: Bonding Theories
Molecular Geometry
VSEPR (Valence-Shell Electron-Pair Repulsion): Minimizes
electron-pair repulsion
Electron Domain: A region in which it is most likely to find electrons (bonding pairs
of electrons)
Electron Domain Geometry: Arrangement of electron domains about the central
atom Molecular Geometry: Arrangement of the atoms in space
Total
electron
domain
Electron-domain
geometry
2 pairs
Linear
3 pairs
Trigonal Planar
3 pairs
Trigonal Planar
4 pairs
Tetrahedral
4 pairs
Tetrahedral
4 pairs
Tetrahedral
5 pairs
Trigonal bipyramid
5 pairs
Trigonal bipyramid
5 pairs
Trigonal bipyramid
5 pairs
Trigonal bibyramid
6 pairs
Octahedral
6 pairs
Octahedral
6 pairs
Octahedral
Nonbonding
domains
Molecular geometry
0
Linear
0
Trigonal Planar
1
Bent
0
Tetrahedral
1
Trigonal Pyramid
2
Bent
0
Trigonal bipyramid
1
Seesaw
2
T-shaped
3
Linear
0
Octahedral
5
1
Square pyramid
4
2
Square planar
Bonding
domains
2
3
2
4
3
2
5
4
3
2
6
90 ̊
More than one Central Atom: Split into multiple known structures
Bond Dipole: Dipole moment between 2 atoms in a bond. It’s a vector quantity
Hybridization: Orbitals formed by mixing two or more atomic orbitals on an atom
Linear = sp hybrid
Trigonal Planar = sp2 hybrid Tetrahedral = sp3 hybrid Trigonal
bipyramid = sp3d hybrid Octahedral = sp3d2 hybrid
Sigma Bond : Single bonds and lie on bond axis. Stronger than pi bonds.
Pi Bond : 2 unhybridized P orbitals overlapping parallel to the bond axis.
Pi bonds break first, and larger atoms form pi bonds less readily
Will only form with sp and sp2 hybrids since it needs an unhybridized p orbital to be
present
Double and Triple bonds produce smaller bond lengths and produce more repulsion
than singles
Example: How many hybridized pairs on CO
:C O: 2 pair on C, and 2 pair on O (don’t
include pi bonds)
Diamagnetic: No unpaired electrons
Causes substances to be repelled from induced
magnetic fields
Paramagnetic: Having unpaired electrons
Causes substances to be attracted into an
induced magnetic field Electrons are not necessarily confined to bonds localized
between 2 atoms The more unpaired electrons, the stronger the force of attraction
is
Delocalized Electrons: Molecules with resonance structures that have pi bonds that
can extend over more than two bonded atoms
Usually happens in molecules with pi bonds and more than one resonance structure
Hybridization Quiz
http://www.sciencegeek.net/Activities/structures/hybridization.html
Bonding Quiz – Topic 8
http://www.adriandingleschemistrypages.com/apquiz.html
Book Companion Site Mastering Chemistry http://masteringchemistry.com/
Tutorials http://www.kentchemistry.com/aplinks/chapters/9CovalOrbitals.htm
Flashcards http://www.funnelbrain.com/sid-21-ap-chemistry.html
- select Molecular Geometry