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Chemistry LibreTexts

Molecular Orbital Diagrams of Diatomics (Worksheet)

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Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.

In chemistry molecular orbital (MO) theory is a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule. In this theory, each molecule has a set of molecular orbitals.

Objectives

  • Practice energy diagrams for molecular orbital theory.
  • Calculate the number of bonding and antibonding electrons in simple molecules.
  • Calculate bond order for simple molecules.
  • Determine the magnetism of simple molecules.

 

Procedure

  • Draw the lewis structure for the following molecules.
  • Fill in the MO diagram that corresponds to each of the molecules given.
  • Determine the number of bonding and antibonding electrons for each of the molecules.
  • Determine the number of sigma and pi bonds for each of the molecules.
  • Calculate bond order and determine magnetism

Summarize your findings for each molecule by determining if this molecule would exist and write the MO electron configuration.

H2          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

H2+          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      
He2          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

He2+          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      

 

Li2          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

Be2          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      

 

B2          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

N2          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      

 

N2+          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

O2          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      

 

O22-          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

O2-          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      

 

NO          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      

 

CO          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

CN          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

CO-          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      

 

NO2-          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration:      


 

NO+          
Lewis Structure:   Molecular Orbital Energy Diagram
MO_blank_for_2nd_period.jpg
  MO_exception_diagram.jpg  
Total # of bonding electrons   # of Sigma Bonds   Bond Order  
Total # of antibonding electrons   # of pi Bonds   Paramagnetic/Diamagnetic  
Should this molecule exist? MO electron configuration: