1. Polar Molecular Compounds
SWBAT: Identify Polar and Nonpolar Molecules

2. Polar Covalent Bond
Each side of the molecule has a small charge due to the electrons being UNEQUALLY SHARED. H Cl
A dipole (two poles) has been created.
Electron density diagram - more electron density around the chlorine
Chlorine has a higher electronegativity than hydrogen.
The “” symbol (delta) stands for small amount/change.

3. + - + H O H - + The bonds in the water molecule are POLAR.
Bond Polarity in Water
The bonds in the water molecule are POLAR.
The molecule is ALSO ASYMMETRICAL.
These TWO factors cause the MOLECULE to be polar. + H - O H H - O + O H + - + H H
The water molecule is a
DIPOLE - it has two oppositely charged “poles”.

4. B: Polarity of Entire Compounds - with multiple, different bonds
Use EN to rate each bond in a compound
Find overall shape of compound
Find Net Dipole Moment: sum of all vectors
Note:
Molecules can have polar bonds, but overall they are not polar!!!!
Opposing bond moments cancel each other out
Unpaired Valence e- also influence shape

5. Non-Polar Molecules with Polar Bonds
IF - The molecule is symmetrical…
There is no overall polarity on the molecule.
The MOLECULE IS NON-POLAR!
CF4
Eneg = = 1.5
* Polar Bonds * F C

6. Which of the following molecules have a dipole moment?
H2O, CO2, SO2, and CH4 O H S O
dipole moment
polar molecule
dipole moment
polar molecule C H C O
no dipole moment
nonpolar molecule
no dipole moment
nonpolar molecule
10.2

7. Identify the Polar and Nonpolar Molecules

8. Polarity of compounds: Why bother?
Important for determining: Solubility
Recite solubility rules!
Water is a polar solvent: only polar compounds will dissolve in water
Benzene: is a non-polar solute: only non-polar compounds will dissolve in benzene

9. Is the molecule symmetrical?
Is a molecule polar?
Are the bonds polar?
0.5 < EN diff < 1.7
YES – POLAR BONDS
Is the molecule symmetrical? NO
POLAR MOLECULE
YES
NON-POLAR MOLECULE
NO – NON POLAR BONDS

10. Polar/Non-polar molecules
Substance
ΔEneg
Bond Polarity
Molecule
Symmetry
Polarity
HCl
BrCl
H2O
CBr4
NH3
PBr3Cl2
CH3I
SI6
CH3Cl
CH3OH