FINAL - Chapter 4 MO Theory Flashcards
(10 cards)
Define MO theory
Electrons delocalized over entire molecule and results by the combination of atomic orbitals
After they combine, atomic orbitals cease to exist in such way that there is no way of knowing which atom e is from
Define bonding, antiobonding and nonbonding MO
Bonding: Constructive, greater electron density, net attractive force
Antibonding: Destructive, little electron density between nuclei, net repulsive force
Nonbonding: Electron density causes no net force, MO analogy to lone pairs
Why are bonding MO’s lower in energy than the original atomic orbitals?
The electrons are closer to the nucleus because electron density concentrated between nuclei, there is less repulsion so consequently less energy
What is the secnod row of the periodic table elements?
Little Berries Bring Colour, Nourishing Our Farms
Li, Be, B, C, N, O, F
What is binding energy?
If you’re given the binding energy to be 4 of the free atom, and 2 of antibonding MO, what is the binding energy of the antibonding?
Binding energy is energy required to remove electron
Since antibonding has more electron repulsion it requires less energy to remove electron
Binding energy of bonding would be 6 so it’s of equal distance
Bond order in MO theory?
What does BO of 0 mean?
BO: (e in bonding MO - e in antibonding MO)/2
BO of 0 means molecule doesn’t exist
What is the symmetry of px, py, and pz1
Px and py are both pi symmetry and pz is sigma symmetry
What is the condition in order to mix orbitals?
Have the same symmetry and be close in energy
When is the one time sigma than pi?
If homo and oxygen or higher
Main difference between valence bond theory and molecular orbital theory?
In valance bond theory, electrons are localized in bonding and lone pairs whereas in MO theory, electrons are delocalized across the molecule
