Bonding Molecular orbital theory - molecular orbital theory Flashcards
constructive waves definition
waves which overlap in the same phase which produce a greater amplitude.
destructive waves definition
waves which overlap in different phases which produce no amplitude.
how are antibonding molecular orbitals formed
The electrons in atomic orbitals will act as deconstructive waves and overlap out of phase, producing a higher energy orbital where electrons will fill after the bonding orbital.
how are bonding molecular orbitals formed
The electrons in atomic orbitals will act as constructive waves and overlap in phase, producing a lower energy orbital where electrons will fill before the antibonding orbital.
wave function of bonding molecular orbital
ψ = CaXa + CbXb
wave function of molecular orbitals
ψ* = CaXa - CaXb
ψ = CaXa + CaXb
c stands for weighting co efficient.
x stands for atomic orbital wave function.
ψ stands for molecular orbital wave function.
how do you show that an orbital is an antibonding molecular orbital
you use a *
antibonding molecular orbitals features
antibonding molecular orbitals will always contain an extra nodal plane than bonding molecular orbitals due to destructive waves overlapping to produce a part of the wave function which will pass through 0.
s atomic orbitals linear combination of atomic orbitals
same sign s orbitals form σg
opposite sign s orbitals will form σu*
g meaning
g stands for even
(gerade)
when a molecular orbital remains in the same phase after being rotated 180 degrees around the bond axis.
u meaning
u stands for odd or ungerade:
this is where when you rotate the bond 180 degrees around the bond axis the phase will change.
u orbitals
σ* and π
antibonding sigma and bonding pi
g orbitals
σ and π*
bonding sigma and antibonding pi
numerical proof for u and g
if when +orbital = (x,y,z), -orbital = -(x,y,z) it is u
if when + orbital = (x,y,z), - orbital = (x,y,z) then it is g.
when would you use u and g
when you have homonuclear atoms bonding with the same type of orbital.
bond order formula
(number of electrons in bonding orbitals - number of electrons in antibonding orbitals) / 2
which molecular orbitals fill first
bonding molecular orbitals fill first since they are lower energy.
what does a bond order of 0 show
the molecular structure will not be possible.
bond order rules
as the bond order increases the bond strength increases and bond length will decrease.
oxidation of molecules effect on bond order
oxidation is a loss of electrons, which will mean that electrons will be lost from the HOMO, this will alter the bond order.
reduction of molecules effect on bond order
reduction is a gain of electrons, so electrons will fill the LUMO.
LUMO
the lowest unoccupied molecular orbital
HOMO
the Highest occupied molecular orbital.
SOMO
A singularly occupied molecular orbital