CHM 1046C Name:___Answers________
Module
4iii - Part Q: Formal Charge
1 point
1. Using the method of the octet rule, the following structure was drawn:
|
Assign the formal charge to
each atom in the Lewis Structure Show the nonzero formal
charges on the Lewis structure by Placing them in circles
alongside the atoms |
Formal Charge |
= |
Valence Electrons |
- |
Nonbonding Val
Electrons |
- |
Bonding
e1- 2 |
= |
Total |
S |
= |
6 |
- |
0 |
- |
4 |
= |
+2 |
O- |
= |
6 |
- |
6 |
- |
1 |
= |
-1 |
O= |
= |
6 |
- |
4 |
- |
2 |
= |
0 |
O- |
= |
6 |
- |
6 |
- |
1 |
= |
-1 |
Sum of
the formal charges in the molecule = __0__
2. Using the method of the formal charge, the following structure was drawn:
|
Assign the formal charge to
each atom in the Lewis Structure Show the nonzero formal
charges on the Lewis structure by Placing them in circles
alongside the atoms |
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___
Explain why the structure in #2
is more preferred than #1!
Structure #2 has no formal charges on any atom, while structure #1
has two negative charges and one positive charge on three of the four atoms.
Both give a net formal charge of zero and are feasible structures, but #1 has
three positive and negative charges from something that is electrically neutral
which results in a higher potential energy. In general the lower the potential
energy the more stable is the structure. #2 is preferred!
3.Using the method of the octet rule, the following structure was drawn:
|
Assign the formal charge to
each atom in the Lewis Structure Show the nonzero formal
charges on the Lewis structure by Placing them in circles
alongside the atoms |
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____
4. Using the method of the octet rule, the following structure was drawn:
|
Assign the formal charge to
each atom in the Lewis Structure Show the nonzero formal
charges on the Lewis structure by Placing them in circles
alongside the atoms |
Formal Charge |
= |
Valence Electrons |
- |
Nonbonding Val
Electrons |
- |
Bonding
e1- 2 |
= |
Total |
S |
= |
6 |
- |
0 |
- |
4 |
= |
+2 |
-O- |
= |
6 |
- |
4 |
- |
2 |
= |
0 |
H- |
= |
1 |
- |
0 |
- |
1 |
= |
0 |
O- |
= |
6 |
- |
6 |
- |
1 |
= |
-1 |
-O- |
= |
6 |
- |
4 |
- |
2 |
= |
0 |
H- |
= |
1 |
- |
0 |
- |
1 |
= |
0 |
O- |
= |
6 |
- |
6 |
- |
1 |
= |
-1 |
Sum of the formal charges in the
molecule = __0___
Explain why the
structure in #4 is more preferred than #3!
#3 has no formal charges on any atom; while #4 has two negative and
one positive charge on three of the 7 atoms. Both are feasible, but #4 has
higher potential energy than #3.