Molecular Orbital Theory

1
Molecular Orbital Theory

• Atomic orbitals mix together and make
• Bonding Orbitals
• Electrons in these orbitals help hold atoms near
  each other
• Antibonding Orbitals
• Electrons in these orbitals push atoms apart from
  each other
• Nonbonding Orbitals
• Electrons in these orbitals have no effect on
  bonding

• Molecular Orbitals can
• be Sigma or Pi
• be spread over multiple atoms

2
Molecular Orbital Theory

• Molecular Orbitals can
• be Sigma or Pi
• be spread over multiple atoms

3
MO Diagram for H2H H ? H2
4
Li2
Bond Order 2 electrons in a bonding orbital 1
bond 2 electrons in an antibonding orbital -1
bond
5
H2/He2 Examples
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What is the bond order of H2

1. 0
2. 0.5
3. 1
4. 1.5
5. 2

7
What is the bond order of H2-

1. 0
2. 0.5
3. 1
4. 1.5
5. 2

8
What is the bond order of He2

1. 0
2. 0.5
3. 1
4. 1.5
5. 2

9
What is the bond order of He2

1. 0
2. 0.5
3. 1
4. 1.5
5. 2