1. Do Now:
Draw the complete Lewis structures for the following:
CH3OH NO IBr2-1

2. O O O . . . . . . . Bonding Basics (review)
Ozone anyone? Draw the Lewis structure for O3 . . . . . O O O
18 VE -4 . . 14

3. O O O . . . . . . . Bonding Basics (review)
Ozone anyone? Draw the Lewis structure for O3 . . . . . O O O
18 VE -4 . . 14

4. O . Bonding Basics (review)
Ozone anyone? Draw the Lewis structure for O3 O .

5. O . Bonding Basics (review)
Ozone anyone? Draw the Lewis structure for O3 O .

6. O . Bonding Basics (review)
Ozone anyone? Draw the Lewis structure for O3 O .

7. CO2 has 3 resonance structures. Try drawing them now!
Bonding Basics (review)
Ozone anyone? Draw the Lewis structure for O3 O .
CO2 has 3 resonance structures. Try drawing them now!
Resonance structures are used to represent bonding in a molecule when one single Lewis structure does not accurately represent it.

8. CO2 has 3 resonance structures. Try drawing them now!
So Lewis Structures aren’t always perfect and can be drawn different ways ... are they all acceptable and accurate versions of a single molecule ???
CO2 has 3 resonance structures. Try drawing them now!

9. Formal Charge An indicator of the validity of the resonance structures
What is it? The “charge” on an atom within a molecule or polyatomic ion +1
The Formula: (try it on CO2)
V.E. -
[ L.P.E. + ½ B.E. ]
Draw the Lewis structure for NH4+1 and assign formal charges to each element.

10. Formal Charge An indicator of the validity of the resonance structures
Important Points
1. The sum of all formal charges equals the total charge or that species +1
2. Show’s the location of the (+) and (-) on a polyatomic

11. Formal Charge So what is the point???
Formal charge can be used to refine a Lewis structure OR pick which resonance structures are the best representation of a particle

12. Formal Charge
Formal charge can be used to refine a Lewis structure OR pick which resonance structures are the best representation of a particle
Guidelines:
FC’s will be distributed so that all atoms are as close to 0 as possible
If a (-) is present, it should be on the most electronegative atom

13. Practice:
OCN-1 has 3 resonance structures. Which of them contribute significantly to the electronic structure of the molecule?