PaRT 4- Molecular Orbital method of Chemical Bonding and molecular Interactions Reference: Chapter 10 in textbook
1 PART 4 – Molecular Orbital Method of Chemical Bonding, and Molecular Interactions Reference: Chapter 10 in textbook
Molecular Orbital(MO)Method MO method Molecular orbitals are formed by combination of atomic orbitals of bonding atoms of total mos a f of total atomic orbitals All es belong to the molecule, not original atoms Electrons are filled based on the same criteria as in atomic orbitals:Pauli exclusion principle; (i Filled from the lowest energy first, (Ground State)
Molecular Orbital (MO) Method MO method Molecular orbitals are formed by combination of atomic orbitals of bonding atoms; # of total MOs = # of total atomic orbitals; All e’s belong to the molecule, not original atoms. Electrons are filled based on the same criteria as in atomic orbitals: (i) Pauli exclusion principle; (ii) Filled from the lowest energy first, (Ground State). 2
Molecular Orbital(MO)Method Bonding, Antibonding, Nonbonding MOS Bonding Mo: W/energy lower than origianl Ao Antibonding MO: W/ energy higher than original Ao Nonbonding MO: W/energy equal to orignal ao; of bonding Mo=# of antibonding MO (P2 3
Molecular Orbital (MO) Method Bonding, Antibonding, Nonbonding MOs Bonding MO: w/ energy lower than origianl AO; Antibonding MO: w/ energy higher than original AO; Nonbonding MO: w/ energy equal to orignal AO; # of bonding MO = # of antibonding MO. 3
Homonuclear diatomic molecules Bond Order=0.5* bonding e-# antibonding e) Larger bond order More stable molecule When bond order =0. it means this molecule cannot exist Example: 1st period elements 01s H H H He He He Q: EXplain(1)why H2, He2 t ions can exist?(2) What is the bond order of these ions
Homonuclear Diatomic Molecules Bond Order = 0.5 * (# bonding e – # antibonding e) Larger bond order ↔ More stable molecule When bond order = 0, it means this molecule cannot exist. Example: 1st period elements Q: Explain (1) why H2 - , He2 + ions can exist? (2) What is the bond order of these ions? 4 H H2 H He He2 He
MO of Li2 and Be2 2s 02s 01s 01s Is Is Is 12 Be B Ground State Electron Configuration in MO Li2:(σ1)2(os)2(a2s Be2:(σ1)2(o1)2(2)2(o23)2 Li,: KK(o2) Be2:KK(σ2)2(2
MO of Li2 and Be2 5 Ground State Electron Configuration in MO Li2 :（σ1s)2（σ1s *)2 （σ2s)2 Be2 :（σ1s)2 （σ1s *)2 （σ2s)2 （σ2s *)2 Li2 : KK（σ2s)2 Be2 : KK（σ2s)2 （σ2s *)2