Answer
See image below.
Work Step by Step
1. Move the electrons.
- Remove the pair of electrons where the arrow has its tail.
- Add that pair to the head of the arrow.
2. Analyze what happens to the atoms related to the arrow.
a. The C atom now has 3 bonds and no lone pairs:
4 - $\frac12$(6) = +1
The O atom now has 1 bond and 3 lone pairs:
Charge = 6 - (6 + $\frac12$(2)) = -1
b. This C is losing a lone pair and gaining a bond.
4 - $\frac 12$(8) = 0
The other C is gaining a bond and losing another, so its charge should not change: 0
The last C loses a bond and gains a lone pair:
4 - (2 + $\frac 12$(6)) = -1
