This document discusses polarity in molecules. It defines electronegativity as a measure of an atom's ability to attract electrons, and explains that polarity arises from differences in electronegativity between atoms in a molecule. The document outlines an experiment using mixtures to demonstrate polarity, defines polar and nonpolar covalent bonds, and introduces the VSEPR theory for predicting molecular geometry. Key concepts are illustrated with examples like HCl, CH4, and NH3.

1. Polarity
of
Molecules

2. 1) Predict the results of the mixture.
2) Define electronegativity
3) Find the electronegativity of elements in the
periodic table.
4) Explain the VSEPR theory
5) Draw the geometry of molecules using the
VSEPR theory

3. Important terms that learners will encounter
a.Electronegativity
b.Covalent bond
c.Valence electron
d. Miscible
e. Dipole
f.Immiscible

4. Polarity Experiment
Materials
Water
Vinegar
Vegetable oil
Gasoline
 Test tubes or graduated
cylinder
 Stirring rod
 Food coloring (optional
for coloring water and
vinegar)

5. Polarity Experiment
Procedure
1. Mix the following samples
well with a spoon and observe
their reactions
2. Stir the mixture.
3. Remember to wash and dry
the stirring rod after each use.
Group I: Water + vinegar
Group II: Water + oil Group
III: Water + gasoline Group
IV: Oil + vinegar Group V:
Oil + gasoline
Group VI: Honey +
gasoline

6. Mixture Mixed (/) Not Mixed (X)
Water + vinegar
Water + oil Water
+ gasoline Oil +
vinegar Oil +
gasoline
Honey + gasoline

7. Find it!
 boiling points
 melting points
 oxidation number
 Atomic number
 Atomic weight/ atomic mass
 Electronegativity

8. Two factors that determine the polarity of
molecules.
1.polarity of the bonds between atoms which
can be studied based on electronegativity
2.the geometrical shape of the molecule which
can be predicted via the valence shell electron
pair repulsion (VSEPR) theory

9. Electronegativity (EN)
- measure of the relative tendency of an atom to
attract electrons to itself when chemically combined
with another atom.
-the higher the value of electronegativity, the more
it tends to attract electrons toward itself.

10. Covalent bond
- is a chemical link between
two atoms or ions where the
electron pairs are shared
between them

11. 2 Types of Covalent bond
1. Polar Covalent Bond
2. Non- polar Covalent Bond

12. Polar covalent bonds
Polar covalent bonds occur when
electron pairs are unequally
shared. The difference in
electronegativity between atoms is
significant

13. Examples of compounds having
polar covalent bonds
HCl
EN of H = 2.1 EN of Cl = 3.0 ΔEN = 0.9

14. Examples of compounds having
polar covalent bonds
HF
EN of H = 2.1 EN of F = 4.0 ΔEN = 1.9

15. The separation of charges makes the bond
polar. It creates an electric dipole. Dipole
refers to “two poles,” meaning there is a
positive and a negative pole within a
molecule.

16. Elements with the higher EN value
become the partial negative pole while
elements with the lower EN value become
the partial positive pole. This makes the
molecule a polar molecule.

17. Non-polar covalent bonds
-occur when electron pairs are
shared equally or the difference in
electronegativity between atoms is
less than 0.5.

18. 1. H2
EN of H = 2.1 ΔEN = 0.0 NON-
POLAR MOLECULE; not a dipole

19. 2. Cl2
EN of Cl = 3.0 ΔEN = 0.0 NON-POLAR MOLECULE; not a dipole
3. F2
EN of F = 4.0 ΔEN = 0.0 NON-POLAR MOLECULE; not a dipole

20. Seatwork
Compound
ΔEN Type of Covalent
Bond
Dipole/
Not Dipole
CH4
CF4
HBr
O

21. Polar or Non-Polar
1.H20
POLAR
2.SF2
POLA
R
3. CO2
NON-POLAR
4. BF3
NON-POLAR

23. Answer key
EN of C = 2.5
EN of F = 4.0
EN of Br = 2.8
ΔEN = 0.4 Non polar covalent bond
ΔEN = 1.5 Polar covalent bond
ΔEN = 0.7 Polar covalent bond
1. CH4
2. CF4
3.HBr
4. O2
EN of H = 2.1
EN of C = 2.5
EN of H= 2.1
EN of O = 3.4 ΔEN = 0.0 Non polar covalent bond

26. 4. HI
EN of H = 2.1 EN of I = 2.5 ΔEN = 0.4
POLAR MOLECULE; a dipole

27. Valence Shell Electron Pair Repulsion
theory or VSEPR theory
- helps predict the spatial arrangement
of atoms in a polyatomic molecule. The
shapes are designed to minimize the
repulsion within a molecule.

28. Guidelines to determine the VSEPR
shape of a molecule
1.Determine the central atom of a
molecule. The central atom is the least
electronegative element.
2.Count how many valence electrons the
central atom has.

29. 3.Count how many valence electrons
the side atoms have.
4.Create the appropriate Lewis
structure of the molecule.

30. 5.Using the Lewis structure as a guide,
determine the appropriate VSEPR shape
for the molecule.
6.Note how many electrons are shared and
unshared. This will help determine the
appropriate VSEPR shape.

32. EXAMPLE
Compound
Name
Total # of
valence
electrons
Lewis
Structure
Geometric
Shape
Type of
Bond
SiS2

33. Compound
Name
Total # of
valence
electrons
Lewis
Structure
Geometric
Shape
Type of
Bond
CH4

34. Compound Total # of
valence
electrons
Lewis
Structure
Geometric
Shape
Type of Bond
Name
1. CH4
2. NH3
3. CdBr2
4. PH3
5. BCl3

35. Compound
Name
Total # of
valence
electrons
Lewis
Structure
Geometric
Shape
Type of Bond
1. CH4 8 tetrahedral Non-polar
2. NH3 8 Triangular
pyramidal/
tetrahedral
Polar
3. CdBr2 16 Linear Non-Polar
4. PH3 8 Triangular
pyramidal/tetr
ahedral
Polar
5. BCl3 24 Trigonal
Planar
Non-polar