1. Lewis Dot Structure, polarity, molecule shapes, forces
Covalent Compounds 
Lewis Dot Structure, polarity, molecule shapes, forces

2. Electronegativity Scale
Boundary  
*look at what is making the bond*
Non-polar covalent
Polar covalent
Ionic O
O.4
1.7
1.9 3

3. Lewis Dot Structure –Single elements
Steps to draw
Determine valence electrons
Write the Chemical symbol
Place the electrons around the outside of symbol
Dots are used as electrons

4. Lets Draw some element Lewis Dot Structures!
Chlorine
Cl: 7 Valence
(group 17) Cl
Sodium
Na: 1 Valence
(group 1) Na
Carbon
C: 4 valence
(group 14) C

5. Lewis Dot Structures for compounds
A representation of where the electrons are shared in covalent compounds
A line shows a bonding pair of electrons
One line = 2 electrons
A dot show unbonded electrons

6. Preferred bonding H C N O

7. Steps to make LDS for compounds
Determine valence electrons for all elements
Add all the valence electrons together
Total for the compound (MAX #)
Determine placement of elements
Most electro-positive element in center
NEVER Hydrogen
Place bonds to connect , start with single bonds first
Place remaining electrons OR create multiple bond if NEEDED
Multiple bonds are needed ONLY when octet cannot be achieved
Check for octet

8. Example H O H H O H H2O H: 2(1 valence) O: 6 valence Total: 8 valence
Step 3: Draw Structure/ Place bonds and electrons
Step 1:Calculate valence
H2O
H: 2(1 valence)
O: 6 valence
Total: 8 valence
8 valence
-4 (2 bonds)
4 valence left
-4 (lone electrons)
0 valence left!
Step 4:
Check for octet/duet
rule
Step 2: Place elements
H O H
H O H

9. LDS with Multiple bonds
Step 3: Draw Structure
16 valence
4 electrons
12 e- left
Step 1: Calculate Valence
CO2
C: 4 valence
O: 2 x 6 valence
Total valence: 16
Can you even distribute remaining electrons AND have each element obey octet rule?
NO! Time for multiple bonds
12 valence
12 electrons
8 in unbonded pairs
4 in double bonds
Step 2: Which element is the most electro POSITIVE
O C O
O C O

10. Resonance Structure
When multiple valid structures can be drawn for the SAME compound
Multiple electrons can move around within bonds (delocalize)
The real structure is hybrid of all the resonance structures

11. VSEPR Theory
A way to predict the shape and properties of covalent compounds
Bonded and unbonded (unpaired) electrons
V: Valence
S: Shell
E: Electron
P:Pair
R:Repullsion

12. How to predict shapes Draw LSD for the compound
Count the number of unpaired and bonded pairs around the CENTRAL ATOM
Predict shape

13. Types of Shape
Open page 14 and 15 in the bonding packet for full list

14. Polarity Electronegativity difference within a molecule
No difference/slight difference/symmetrical molecule: Non- polar
Large difference/ non-symmetrical molecule: Polar
Dipole: two poles with difference partial charges

15. Is it polar? Polar: not symmetrical Polar: Unbonded pairs
Non-Polar: poles are the same
Non-Polar: symmetrical

16. Intermolecular Forces
Van Der Walls, London Dispersion, Induced Dipoles
Dipole-Dipole
Hydrogen Bonding

17. Van Der Walls, London Dispersion, Induced Dipole
Random movement of electron creates a temporary negative and positive pole
All electrons are on one side

18. Dipole-Dipole When there is an Electronegativity difference
One side has a partial negative (bonding pair closer to the high EN)
One side has partial positive (bonding pair further away from the low EN)

19. Hydrogen Bonding NOT REAL BONDING: type of dipole-dipole
ONLY when H is bonded to N,F, or O

20. What force goes with what?
Polar Molecules
Non-polar molecules
Dipole-dipole
Hydrogen bonding
ONLY when H is bonded to N,F, or O
London Dispersion
London Dispersion