Physical Science :First Semester

1. POLARITY OF
MOLECULES

2. OBJECTIVES OF THE DAY!
At the end of this lesson, you should be able to:
• Differentiate polar and nonpolar bonds;
• Determine the polarity of chemical bonds between atoms using the concept of
electronegativity;
• Familiarize with the different molecular shapes;
• Explain how polarity of bonds and molecular geometry affects the polarity of
molecules.

3. INTRODUCTION
MOLECULE

4. INTRODUCTION
• Molecule is a group of two or more atoms
held together by chemical bonds.

5. EXAMPLE OF MOLECULES

6. EXAMPLE OF MOLECULES

7. POLARITY
• It refers to the distribution of electric charge around atoms, chemical groups, or
molecules.

8. 2 FACTORS THAT DETERMINE THE
POLARITY OF MOLECULES
1. The 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. POLARITY OF MOLECULES
• All compounds can be classified based on what type of chemical bond formed
when the atoms combined.
• The classification of the compound can be used to determine whether a molecule
is polar or non-polar.
• The two classifications of compounds are covalent and ionic.

10. COVALENT AND IONIC
• Covalent Compound is a molecule formed by covalent bonds, in which the
atoms share one or more pairs of valence electrons.
• Ionic Compounds are made up of ions rather than molecules. Instead of sharing
electrons in covalent bonds, ionic compound atoms transfer electrons from one
atom to another to form an ionic bond that relies on electrostatic attraction to
keep the atoms together.

11. BOND POLARITY
• ELECTRONEGATIVITY (EN)
• It is the measure of 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 electron
toward itself.

13. ELECTRONEGATIVITY DIFFERENCE
DIFFERENCE IN
ELECTRONEGATIVITY
TYPE OF COMPOUND
(BOND POLARITY)
Greater than or equal to 1.7 IONIC
0.5 POLAR
Less than 0.5 COVALENT NON-POLAR

14. EXAMPLE
I. Predict whether the bond type between the following pairs of atoms will be
ionic, polar covalent, or nonpolar covalent.
1. C and Cl
2. Mg and O
3. H and Cl
4. N and N
5. K and F

15. MOLECULAR POLARITY
• For polyatomic molecules, both the bond polarity and molecular shape
determine the overall molecular polarity.
• H2O,CCI4,NH3 and CO2

16. MOLECULAR POLARITY
• In terms of molecular geometry, the valence shell electron pair repulsion
(VSEPR) theory would help us to determine the spatial arrangement of atoms in
a polyatomic molecule.

18. THE END