1.
POLAR AND NON POLAR
MOLECULES
P.JEEVANANTHAM
3rd - BSc chemistry
Department of chemistry
NGM College
Pollachi.

2.
What is Polar molecule?
 A Polar Covalent Bond is unequal sharing of electrons between
two atoms
 Polar bonds are form when there is a different between the
electronegativity values of the atoms participating in a bond
 Electron density is distributed asymmetrically throughout the molecule
EXAMPLES : NH3 H2S

3.
Cl H

4.
What is Non Polar molecule?
 A Polar covalent is EQUAL sharing of electrons between
two atoms
 Polar bonds are form when there is a similar the electronegativity
values of the atoms participating in a bond.
 Electron density is distributed symmetrically within the molecule
 EXAMPLE :
 H2 Cl2 BF3


5.
H H

6.
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.

7.
Practice
What type of bond is HCl ? (H = 2.1, Cl = 3.1)
Difference = 3.1 – 2.1 = 1.0
Therefore it is polar covalent bond.
Your Turn To Practice
 N(3.0) and H(2.1) = 0.9 (polar)
 Al(1.5) and Cl(3.0) = 1.5 (polar)
 Mg(1.2) and O(3.5) = 2.3 (ionic)
 H(2.1) and F(4.0) = 1.9 (polar)
 H(2.1) and H(2.1) = 0 (non polar)
 Ca(1.0) and Cl(3.0) = 2 (ionic)

8.
Summary
 In a polar bond, one atom is more electronegative than the
other.
 In a nonpolar bond, both atoms have similar
electronegativity's.
 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.

9.
Polar = A,B,E
Non polar = C,D
Questn 1
Example:
Identify each of the following compounds as
either a polar molecule or a nonpolar
molecule.
A. NH3
B. CHCl3
C. CO2
D. BF3
E. CO

10.
DIPOLE MOMENT
AND
APPLICATION OF DIPOLE MOMENTS
IN STUDY OF SIMPLE MOLECULE

11.
The product of magnitude of negative or positive charge(q) and the
distance between the centres of the positive and negative charges is
called dipole moment.
It is usually donated by µ.
 A dipole moment is a quantity that describes two opposite charges
separated by a distance
OR
 If a molecule has a dipole moment,then we call it “polar”.
 Dipole moment is a vector quantity i.e. it has magnitude as well as
direction.

12.
DRAW DIPOLE MOMENT
Dipole moment is a vector quantity and is represented by a small arrow
with tail at the positive center and head pointing towards a negative center.
For example,
the dipole moment of HCl molecule is 1.03 D and the dipole of HCl may be
represented as:

13.
FORMULA
 A quantitative measures of the polarity of a bond its dipole moment. μ which
is the product of the charge Q and the r is distance between the charges

Q is charge of electron = 1.60217662 × 10-19 coulombs
r is a distance
µ = Q × r
1 D = 3.335 × 10-30 C m (SI units)

14.
EXAMPLE
Carbon
tetrachloride
m = 0 D
Carbon tetrachloride has no dipole
moment because all of the individual
bond dipoles cancel.

15.
m = 1.62 D
The individual bond dipoles do not
cancel in dichloromethane; it has
a dipole moment.

16.
Greater the electronegativity difference between the bonded atom, greater if the dipole
moment.
Dipole moment of hydrogen halides are in the order :
H-F > H-Cl > H-Br > H-I

17.
APPLICATION
1)In determining the polarity of bonds :
Greater is the magnitude of dipole moment,higher will be the polarity of the bond.
This is applicable to molecules containing only one polar bond.
In case of non-polar molecules like H2 , O2, N2 etc, the dipole moment is found to be zero .
This is because there is no charge separation in these molecules.
2)In determining the symmetry of the molecules
If any molecule possesses two or more polar bonds ,it will not be symmetrical if it possesses
some molecular dipole moment.
Water µ= 1.84 D
H2S µ = 0.95 D
NH3 µ=1.47 D

18.
If a molecule contains a number of similar atoms linked to the central atom and the
overall dipole moment of the molecule is found to be zero ,this will imply that the
molecule is symmetrical.
For Ex: BF3 , CH4 , CCl4
4) To distinguish between cis and trans isomer
Cis isomer usually has higher dipole moment than trans isomer
5)To distinguish between Ortho, meta and para isomers
The dipole moment of para isomer is zero and that of ortho is greater than that of
meta.

19.
SUMMARY
 Molecular dipole depends on the geometry of the molecule
 When the molecule does not possess a net dipole moment, the
molecule is nonpolar.
 When the molecule possesses a net dipole moment, the molecule is
polar.

20.
REFERENCE:
 http://nobel.scas.bcit.ca/wiki/index.php/Polarity_of_molecules
 http://accafkenya.org/polarity-of-molecules-worksheet-answers/polarity-of-
molecules-worksheet-answers-worksheets-polarity-of-molecules-worksheet-
opossumsoft-templates/
 https://www.google.co.in/search?biw=1242&bih=535&tbm=isch&sa=1
&ei=XimUWo7oHY6avQTEyIGoDg&q=polar+and+non+polar+molecule+p
pt&oq=polar+and+non+polar+molecule+ppt&gs
 https://en.wikipedia.org/wiki/Chemical_polarity
 https://study.com/academy/lesson/polar-and-nonpolar-covalent-
bonds-definitions-and-examples.html

21.
dipoles:
CO,NF3,SCl4
No dipoles:
PF5,SCl6,CCl4,BF3
Questn 2
From the following identify the dipole molecules?
PF5
CCl4
CO
SCl4
SCl6
BF3
NF3

22.
THANK YOU !