molecular orbital theory

phase signs of wave functions cause

constructive or destructive interference

interference changes

probability of finding electrons

number of molecular orbitals is always equal to 

the number of atomic orbitals that combine (e.g. H2 has two MOs, the bonding and antibonding)

adding in the same phase causes

a bonding orbital, with lower energy than the atomic orbitals

subtracting in opposite phases/adding destructively causes

an antibonding orbital, designated with * - causes a node between the nuclei

bond order =

½ (no of bonding e- — no of antibonding e-)

when doing MO theory of period 2 atoms, can

ignore 1s electrons

bond order can be calculated with

all electrons OR just valence electrons

when doing MO theory move from

bottom to top filling the electrons

resonance

molecules with delocalized electrons that can’t be well described as being in one particular bond; applies to π orbitals