1. Review
Polar Covalent: unequal sharing of electrons (electronegativity difference >0.4)
Nonpolar Covalent: equal sharing of electrons (electronegativity difference <0.4)

2. Polar Covalent Bond
A Polar Covalent Bond is unequal sharing of electrons between two atoms (H-Cl) in an ASYMMETRICAL molecule
In a polar covalent bond, one atom typically has a slight negative charge, and the other atom has a slight positive charge

3. Nonpolar Covalent Bond
A Nonpolar Covalent Bond is an equal sharing of electrons between two atoms (Cl-Cl, N-N, O-O)

5. Classification of Bonds
You can determine the type of bond between two atoms by calculating the difference in electronegativity values between the elements The bigger the electronegativity difference the more polar the bond.
Type of Bond
Electronegativity Difference
Nonpolar Covalent
0  0.4
Polar Covalent
0.5  1.9

6. *Exception!!!!!
If molecule is symmetrical it is NONPOLAR!

7. Summary
In a polar bond, one atom is more electronegative than the other (>0.4 difference).
In a nonpolar bond, both atoms have similar electronegativities (<0.4 difference).
An asymmetric molecule with polar bonds is a polar molecule.
An asymmetric molecule with nonpolar bonds is a nonpolar molecule.
A symmetric molecule, regardless of the polarity of the bonds, is always a nonpolar molecule.

8. Practice-Polar/Nonpolar
CO2
H2O
BF3
NH3
CCl4

9. Polar/Nonpolar

10. INTRAmolecular Forces
“Within” the molecule and are called covalent and ionic bonds.

11. INTERmolecular Forces
Forces that occur between molecules.
Intramolecular (ionic and covalent) bonds are stronger than intermolecular forces.

12. Khan Academy

14. How Strong?
The higher the boiling point = stronger the IMFA

15. Intermolecular Forces
Dipole-dipole
Hydrogen bonding!
Dipole-induced dipole
London dispersion forces

16. 12.6 Dipole–Dipole Attraction
Polar molecules contain different
atoms which have different
electronegativity's and can be
thought to be like a small bar
magnet. Oppositely charged ends attract and like ends repel. Molecules organize themselves to maximize the attractive forces
and minimize repulsive forces
giving molecules unique shapes.

17. 12.6 Hydrogen Bonding Strong dipole-dipole forces.
Strongest intermolecular force
Hydrogen is bound to a highly electronegative atom – nitrogen, oxygen, or fluorine. “FON”

18. Hydrogen Bonding in Water
Blue dotted lines are the intermolecular forces between the water molecules.

19. 12.6 Hydrogen Bonding
Affects physical properties
Boiling point

20. Dipole-Induced Dipole
When a polar molecule gets near a non-polar one, it induces the non-polar one to become polar; thus, they connect

21. 12.6 London Dispersion Forces
Instantaneous dipole that occurs accidentally in a given atom induces a similar dipole in a neighboring atom.
Significant in large atoms/molecules.
Occurs in all molecules, including nonpolar ones.
Weakest IMFA

22. 12.6 London Dispersion Forces
Become stronger as the sizes of atoms or molecules increase.
Larger mass=stronger LDF=higher BP

23. CFU
1. Put the following intermolecular forces in order from strongest to weakest:
Hydrogen bonding
London dispersion forces
Dipole-dipole
Dipole-induced dipole
2. Which would have a higher BP: CH4 or C2H6? Why?

24. Draw LDDs for: BeH2 (no octet) PO43- BCl3 (no octet) SO2
- Is it POLAR or NONPOLAR?
-IMFA a)1&2,b)3&4,c)1&3,d)2&3?

25. Draw LDDs & Predict Polarity:
CF4 2) CO2
3) SeCl4 4) XeF4
- Is it POLAR or NONPOLAR?
-IMFA a)1&2,b)3&4,c)1&3,d)2&3?