Chapter 5 - Molecular Orbitals Flashcards
d orbital: z2
d orbital x2-y2
dxy
dyz
dxz
π-bond
a change in sign in the wave function with C2 rotation about the bond axis
one node including the line between nuclei
δ-bond
change in sign on C4 rotation about the bond axis
two nodes including the line between nuclei
σ-bond
orbitals are symmetric to rotation about the line connecting the nuclei
no nodes that include the line between nuclei
Conditions for formation of molecular orbitals from atomic orbitals
- Correct symmetry
- Correct/similar energies
- Correct/close enough distances
The ___ the energy match between atoms, the stronger the interaction
closer/lower
Two atomic orbitals have a very large difference in energy. How strong will the interaction between them be?
Very weak. If the atomic orbitals have a very large energy difference, then the resulting molecular orbitals will have energies and shapes closer to the original atomic orbitals.
Bond order
Bond order = 1/2 (# bonding electrons - #antibonding electrons)
gerade
g = gerade, orbitals symmetric (same sign) on inversion
ungerade
u = ungerade, orbitals antisymmetric (signs change) on inversion
Orbital mixing
When molecular orbitals have similar (1) symmetry and (2) energies (e.g. σg/σg*(2s) and σg/σg*(2p) ), then they can interact to magnify the energy differences–lowering the energy of the lower orbital and raising the nergy of the higher orbital
Paramagnetic
Unpaired electrons
Attracted to magnetic field
Diamagnetic
Paired electrons
Repulsed by magnetic field
What is the relationship between bond order/molecular orbitals and bond length?
As the bond becomes stronger (bond order increases) the bond length decreases.
What contribution does electronegativity have on heteronuclear molecular orbitals?
The more electronegative element will have atomic orbitals at lower potential energies than the less electronegative element
