Hybridization and Molecular Orbitals Flashcards
Valence Bond Theory
A more complete theory of bonding, it is based on Quantum Mechanics and explains bond energies and bond lengths.
bond energies
the amount of energy needed to break a bond, usually measured in kj or kj/mol
hybridization
- the mixing of atomic orbitals to form special orbitals for bonding. - gives the minimum energy for the molecule.
- finds perfect distance for potential energy to be the lowest.
degenerate orbitals
orbitals of equal energy. When hybridization orbitals are formed, they are all degenerate to one another.
Sp2 hybridization
- trigonal planar 120 orbital angles
- one p orbital is not hybridized
sigma bonds
- overlap of s or head-on p orbitals
- electron density between the nuclei
- bond rotation is possible.
pi bond
- sideways overlap of the p orbitals
- electron destiny above and below the nuclei
unhybridized p-orbitals are at a _______ energy state
higher
problems with the localized electron model
- incorrectly assumes that electrons are localized and resonance must be added.
- does not work well with molecules w/ unpaired electrons
- does not give direct info on bond energies
molecular orbitals
the quantum mechanical solutions to organization of valence electrons in molecules.
- have many of the same chars:
- holds 2 electrons each
- square of the molecular orbitals wave function indicates electron probability.
types of MO’s:
bonding and anti-bonding MO’s
bonding molecular orbitals
lower in energy than the atomic orbitals it is composed of.
anti-bonding molecular orbitals
higher in energy than the atomic orbitals it is composed of.
bond order
indicates bond strength, with the larger the bond order the stronger the bond # of bonding --- # of anti-bonding all divided by 2
fill the ______ orbitals first
bonding
why can only valence orbitals of atoms contribute significantly to MO’s ?
bc the atomic orbitals must overlap in space to participate in MO’s
paramagnatism
unpaired electrons in MO diagram
attracted to induced magnetic fields
much stronger than diamagnetic
diamagnetism
- paired electrons in MO diagram
- repelled from induced magnetic field
- much weaker than paramagnetism
as bond order increases…
bond energy increases and bond length decreases
bond order is not associated with a particular…
bond energy
triple bond = ______ bond energy
high
O2 is paramagnetic, which is predicted by the
MO model, not the LE model
sigma bonds are…
localized
pi bonds are…
delocalized
