Polar Molecular
Compounds
SWBAT: Identify Polar and
Nonpolar Molecules
Polar Covalent Bond
Each side of the molecule has a
small charge due to the
electrons being UNEQUALLY
SHARED.
A dipole (two poles) has been created.
H
Cl
Electron density
diagram - more
electron density
around the chlorine
Chlorine has a higher electronegativity than
hydrogen.
The “” symbol (delta) stands for small
amount/change.
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
H
O + O 
+
H
H
-
+
H
O
H
+
The water molecule is a
DIPOLE - it has two oppositely charged “poles”.
-
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
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 = 4.0 - 2.5 = 1.5
F
C
F
F * Polar Bonds *
F
Which of the following molecules have a dipole moment?
H2O, CO2, SO2, and CH4
O
S
dipole moment
polar molecule
dipole moment
polar molecule
H
O
C
O
no dipole moment
nonpolar molecule
H
C
H
H
no dipole moment
nonpolar molecule
10.2
Identify the Polar and
Nonpolar Molecules
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 nonpolar compounds will dissolve in benzene
Is a molecule polar?
Are the bonds
polar?
0.5 < EN diff
< 1.7
YES – POLAR
BONDS
NO – NON
POLAR BONDS
Is the molecule
symmetrical?
NO
POLAR
MOLECULE
NON-POLAR
MOLECULE
YES
NON-POLAR
MOLECULE
Polar/Non-polar molecules
Substance
HCl
BrCl
H2O
CBr4
NH3
PBr3Cl2
CH3I
SI6
CH3Cl
CH3OH
ΔEneg
Bond
Polarity
Molecule
Symmetry
Polarity