Module Four III: Part B1 Dot Structures via Formal Charge   7 points

Using a periodic chart draw the electron dot/stick structures of the following molecules. Use the method of formal charges to show the best structure: (Steric Numbers 2-6)

 

H2SO4      Sulfuric Acid  

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

S

=

6

-

0

-

6

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

         

         Sum of the formal charges in the molecule =  __0____

Best: Not Best via Octet:

Formal Charge all atoms = 0; total = 0 Best Structure

                                                                                                             

  H2SO3     Sulfurous Acid

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

S

=

6

-

2

-

4

=

0

O=

=

6

-

4

-

2

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

 

Sum of the formal charges in the molecule =  __0____   

Best: Not Best via Octet:

Formal Charge all atoms = 0; total = 0 Best Structure

 

H3PO4    Phosphoric Acid 

 Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

P

=

5

-

0

-

5

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

O=

=

6

-

4

-

2

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

 

Sum of the formal charges in the molecule =  __0____   

Best:Not Best vis Octet:

 Formal Charge all atoms = 0; total = 0 Best Structure

 

H3PO3       Phosphonic Acid versus Phosphorous acid

 Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

P

=

5

-

0

-

5

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

O=

=

6

-

4

-

2

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

 

Sum of the formal charges in the molecule =  __0____   

Best: Not Best vis Octet:

Formal Charge all atoms = 0; total = 0 Best Structure

 

HClO4            Perchloric Acid                                                                                                                                                     

 

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Cl

=

7

-

0

-

7

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

O=

=

6

-

4

-

2

=

0

 

Sum of the formal charges in the molecule =  __0____   

 

Best: Not Best Via Octet

 Formal Charge all atoms = 0; total = 0 Best Structure

 

 

 

HClO3         Chloric Acid                                                                                                                                                           

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Cl

=

7

-

0

-

7

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

 

Sum of the formal charges in the molecule =  __0____   

Best: Not Best Via Octet:  

 Formal Charge all atoms = 0; total = 0 Best Structure

 

 

HClO2            Chlorous Acid

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Cl

=

7

-

4

-

3

=

0

O=

=

6

-

4

-

2

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

 

Sum of the formal charges in the molecule =  __0____  

 

Best:  Not Best Via Octet:
 Formal Charge all atoms = 0; total = 0 Best Structure

 

 

HClO            HypoChlorous Acid

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Cl

=

7

-

6

-

1

=

0

-O-

=

6

-

4

-

2

=

0

H-

=

1

-

0

-

1

=

0

 

Sum of the formal charges in the molecule =  __0____ 

 

 Octet Rule produces Best Structure
Formal Charge all atoms = 0; total = 0 Best Structure

 

 

 

 

 

 

 

 

 

 

 

   SO2         Sulfur Dioxide                                           

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

S

=

6

-

0

-

6

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

 

Best:  Not Best Via Octet:

Formal Charge all atoms = 0; total = 0 Best Structure

 

 

      SO3   Sulfur Trioxide                                           

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

S

=

6

-

0

-

6

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

        

         Sum of the formal charges in the molecule =  ___0___

 

Best: Not Best Via Octet:

 Formal Charge all atoms = 0; total = 0 Best Structure

   

 

 

 

 

 

 

 

 

 

 

AsF5   Arsenic Pentafluoride                                            

  Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

As

=

5

-

0

-

5

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

 

Sum of the formal charges in the molecule =  ___0___

Formal Charge all atoms = 0; total = 0 Best Structure

 

 

 

SF6   Sulfur Hexafluoride

  Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

S

=

6

-

0

-

6

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

 

Sum of the formal charges in the molecule =  ___0___

Best:

                                                 

Formal Charge all atoms = 0; total = 0 Best Structure

SF4   Sulfur Tetrafluoride

  Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

S

=

6

-

2

-

4

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

 

Sum of the formal charges in the molecule =  ___0___

Best:

 

Formal Charge all atoms = 0; total = 0 Best Structure

 

    SbCl5    Antimony Pentachloride                                                

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Sb

=

5

-

0

-

5

=

0

Cl-

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

Formal Charge all atoms = 0; total = 0 Best Structure

 

 

 

 PCl5     Phosphorus Pentachloride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

P

=

5

-

0

-

5

=

0

Cl-

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

Formal Charge all atoms = 0; total = 0 Best Structure

 

PCl3     Phosphorus Trichloride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

P

=

5

-

0

-

5

=

0

Cl-

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

 Octet Rule prduces Best Structure

Formal Charge all atoms = 0; total = 0 Best Structure

 

 

 

 

 

 

 

PCl61-     Phosphorus Hexachloride Ion

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

P

=

5

-

0

-

6

=

-1

Cl-

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___-1___

                                                                  

 (Not Possible using Octet Rule)

Formal Charge on Phosphorus  atom = -1
Total Formal Charge = -1;  Polyion Charge = -1
All Chlorine atoms formal charge = 0
Best Structure

 

    SeF6    Selenium Hexafluoride

  Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Se

=

6

-

0

-

6

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

Formal Charge all atoms = 0; total = 0 Best Structure

 HArF        Argon Fluorohydride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Xe

=

8

-

6

-

2

=

0

H-

=

1

-

0

-

1

=

0

F-

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

Formal Charge all atoms = 0; total = 0 Best Structure

 

 Br31-      TriBromide Ion

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Br-

=

7

-

6

-

1

=

0

Br-

=

7

-

6

-

2

=

-1

Br-

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___-1___

(Not Possible using Octet Rule)

Formal Charge on middle Bromine  atom = -1
Total Formal Charge = -1;  Polyion Charge = -1
Other two bromine (each side) atoms formal charge = 0
Best Structure

 

 

 

 

 

 

 

 

 

I31-  TriIodide Ion

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

I-

=

7

-

6

-

1

=

0

I-

=

7

-

6

-

2

=

-1

I-

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___-1___

(Not Possible using Octet Rule)

Formal Charge on middle Iodine  atom = -1
Total Formal Charge = -1;  Polyion Charge = -1
Other two Iodine (each side) atoms formal charge = 0
Best Structure

 

 

 

KrF2    Krypton Difluoride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Kr

=

8

-

6

-

2

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

 

Formal Charge all atoms = 0; total = 0 Best Structure

 

 

 

 

 

 

XeF4       Xexon Tetrafluoride

  Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Xe

=

8

-

4

-

4

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

 

Sum of the formal charges in the molecule =  ___0___

 

 

Formal Charge all atoms = 0; total = 0 Best Structure

 

 

 

XeO4     Xexon Tetroxide

  Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Xe

=

8

-

4

-

4

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

 

Sum of the formal charges in the molecule =  ___0___

 Formal Charge all atoms = 0; total = 0 Best Structure

 

 

BrF3      Bromine Trifluoride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Br

=

7

-

4

-

3

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

(Not Possible using Octet Rule)

Formal Charge all atoms = 0; total = 0 Best Structure

 

 

BrF41+  Bromine Tetrafluoride Ion

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Br

=

7

-

2

-

4

=

+1

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

Sum of the formal charges in the Polyion =  ___+1___

(Not Possible using Octet Rule)

Formal Charge on Bromine atom = +1
Total Formal Charge = +1;  Polyion Formal Charge = +1
All Fluorine atoms formal charge = 0
Best Structure

 

BrF5       Bromine Pentafluoride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Br

=

7

-

2

-

5

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

F-

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

(Not Possible using Octet Rule)

Formal Charge all atoms = 0; total = 0 Best Structure

 

 SO2Cl2    Sulfuryl Chloride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

S

=

6

-

0

-

6

=

0

O=

=

6

-

4

-

2

=

0

O=

=

6

-

4

-

2

=

0

Cl -

=

7

-

6

-

1

=

0

Cl -

=

7

-

6

-

1

=

0

Sum of the formal charges in the molecule =  ___0___

Formal Charge all atoms = 0; total = 0 Best Structure

 

Reading Reference: Sections 8.5 Octet Rule and 8.7 Formal Charge (page 374)

Reference Octet Rule: B.   Dot Structures of Covalent Compounds Section 2.10, 6.6, 7.1, 7.5, 7.6

Octet Rule Answers: http://www.fccj.us/chm2045/SampleTest/45M4bAnswers.htm

 

 

Other Ions/Compounds to consider which may be the exam question:

ClF5     AsF61-   SeF4    PF3Cl2  

 

ClF5  Chlorine Pentafluoride

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Cl

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

Sum of the formal charges in the molecule =  _______

 

 

 

 

 

SeF4  Selenium Tetrafluoride       

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

Se

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

Sum of the formal charges in the molecule =  _______

 

 

 

 

 

 

 

PF3Cl2

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

P

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

Cl-

 

 

 

 

 

 

 

 

Cl-

 

 

 

 

 

 

 

 

Sum of the formal charges in the molecule =  _______

 

 

 

 

AsF61-     Arsenic Hexafluoride Ion

Formal

Charge

=

Valence

Electrons

-

Nonbonding

Val Electrons

-

Bonding e1-

        2

=

Total   

As

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

F-

 

 

 

 

 

 

 

 

Sum of the formal charges in the molecule =  _______