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1. Valence Shell Electron Pair Repulsion
through
Theory
JOVELYN B. DAHANG
Pre-Service Teacher

3. LEARNING OBJECTIVES
At the end of the lesson, you will be able to
1. identify the different geometric shapes of
molecules using diagrams ; and
2. Predict the structures and shapes of molecules
using the VSEPR model.

4. REVIEW: Which is the correct Lewis dot structure of
the following atoms/molecules?

5. REVIEW: Which is the correct Lewis dot structure of
the following atoms/molecules?

6. REVIEW: Which is the correct Lewis dot structure of
the following atoms/molecules?
H2O
A

7. Valence-Shell Electron Pair Repulsion
(VSEPR) model
• Used to predict the three-dimensional shape of the
molecules from the electron pairs that surround the
central atoms of the molecule.
• Also referred to as electron domain model.
• Two primary founders of this model are Ronald
Nyholm and Ronald Gillespie.

8. The electron pairs in
the valence shell of a
central atom repel
each other.
Valence-Shell Electron Pair Repulsion (VSEPR) model
BASIC ASSUMPTIONS

9. Three main types of bond repulsion
Lone pair – lone pair repulsion
Lone pair – bonded pair repulsion
Bonded pair – bonded pair repulsion
Valence-Shell Electron Pair Repulsion (VSEPR) model
BASIC ASSUMPTIONS

10. Lone pairs or non-
bonding pairs
exerts greater
repulsion than
bonded pairs.
Lone pair – lone pair repulsion > Lone pair – bonded
pair repulsion > Bonded pair – bonded pair repulsion
Valence-Shell Electron Pair Repulsion (VSEPR) model
BASIC ASSUMPTIONS

11. 3
A multiple bond is treated
as if it is a single electron
pair and the two or three
electron pairs of a multiple
bond are treated as a single
super pair.
Valence-Shell Electron Pair Repulsion (VSEPR) model
BASIC ASSUMPTIONS

12. The ED model assumes that the shape of a molecule can be
predicted by arranging the electrons in a geometry that keeps them
separated as far as possible.

13. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
C O
O C
STEP 2. Count the total number of
electron domains of the central atom
2

14. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Linear
Linear

15. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
STEP 2. Count the total number of
electron domains of the central atom
3
B
F
F
F

16. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Trigonal Planar
Trigonal Planar

17. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
STEP 2. Count the total number of
electron domains of the central atom
3
N O
O NOTE: Nonbonding electrons are
classified as electron domains

18. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Bent
N
O O

19. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
STEP 2. Count the total number of
electron domains of the central atom
4
C H
H
H
H

20. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Tetrahedral
Tetrahedral

21. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
STEP 2. Count the total number of
electron domains of the central atom
4
N H
H
H

22. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Trigonal Pyramidal

23. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
STEP 2. Count the total number of
electron domains of the central atom
4
O H
H

24. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Bent

25. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
STEP 2. Count the total number of
electron domains of the central atom
5

26. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Trigonal
bipyramidal

27. How to determine the actual geometry of a molecule?
STEP 1. Draw the Lewis
Structure.
STEP 2. Count the total number of
electron domains of the central atom
6

28. How to determine the actual geometry of a molecule?
STEP 3. Identify the electron
domain geometry of the molecule.
STEP 4. Identify the molecular group
geometry and the bond angles between
atoms in the molecule.
Octahedral