Chapter 13: Phenomena
Phenomena: Scientists measured the bond angles of some common molecules.
In the pictures below each line represents a bond that contains 2 electrons. If
multiple lines are drawn together these are double or triple bonds and contain 4
and 6 electrons respectively. What patterns do you notice from the data?

b)


Cl C Cl

H N H



H
Cl
Bond Angles: 107˚
H

Bond Angles: 109.5˚
Bond Angles: 109.5˚
f)

O
e)

d)
+
H


H N H


c)
Cl

a)
O

S
C
Bond Angles: 105˚
B
Bond Angles: 120˚
Bond Angles: 119˚
h)
i)

O C

O

O

Bond Angles: 180˚
j)
Bond Angles: 120˚

Bond Angle: 117˚
N

F


g)

C H
Bond Angles: 180˚
Chapter 13: Bonding: General Concepts
Chapter 13
Bonding:
General Concepts
Big Idea: Bonds are formed
from the attraction
between oppositely
charged ions or by
sharing electrons.
Only the valence
electrons participate
in bonding. The shape
of the molecules
maximize the distance
between areas of high
electron density.
2
Types of Bonding
o Electronegativity
o Lewis Structures
o Strength/Length of
Covalent Bonds
o Shapes of Molecules
(VSEPR)
o Polar Molecules
o
Lewis Structure Review

Drawing Lewis Structures that Obey the Octet Rule
CO32-
1(C)
3(O)
2(e-)
Total
Step 1:
(Determine
Valence e-)
Step 2:
(Determine
Wanted e-)

Step 3: Determine number of bonds
𝑤𝑎𝑛𝑡𝑒𝑑−𝑣𝑎𝑙𝑒𝑛𝑐𝑒
# 𝑏𝑜𝑛𝑑𝑠 =
2

3
Step 4: Determine number of electrons
# 𝑒 − = 𝑣𝑎𝑙𝑒𝑛𝑐𝑒 − 2 𝑏𝑜𝑛𝑑𝑠
Chapter 13: Bonding: General Concepts
Lewis Structure Review

Resonance: A blend of Lewis structures into a
single composite hybrid structure.
2-
O
O

C
2-
O
O
O
C
2-
O
O
O
C
O
Formal Charge = Valence e- – e- Surrounding Atom
Note: Loan pairs count for 2 e- and bonds count for 1 e-.
2-
O
O
4
C
O
Chapter 13: Bonding: General Concepts
Lewis Structure Review

Drawing Lewis Structures that Minimize Formal
Charges (Only atoms in period 3 and later can
expand their octets)
SO2
1(S)
2(O)
Total
Step 1:
(Determine
Valence e-)

5
Step 2: Find structure with lowest formal charges
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
VSEPR (Valence-Shell Electron-Pair Repulsion Model):
Extends Lewis’s theory of bonding to account for
molecular shapes by adding rules that account for
bond angle.
 Rule
1: Regions of high electron concentration
(bonds and lone pairs on the central atom) repel
one another and to minimize their repulsion,
these regions move as far apart as possible while
maintaining the same distance from the central
atom.
 Rule 2: There is no distinction between single and
multiple bonds: a multiple bond is treated as a
single region of high electron concentration.
6
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
 Rule
3: All regions of high electron density, lone
pairs and bonds, are included in a description of
the electronic arrangement, but only the
positions of atoms are considered when
reporting the shape of a molecule (molecular
shape).
 Rule 4: The strengths of repulsion are in the order
lone pair – lone pair > lone pair – atom > atom –
atom.
7
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
Assigning Shape and Bond Angles of Molecules
 Step 1: Draw the Lewis structure.
 Step 2: Assign the electronic arrangement
around the central atom (linear, trigonal planer,
tetrahedral)
Note: Electronic arrangement includes all areas of electron density
(lone pairs and bonds).
 Step
3: Identify the molecular shape (linear,
bent, trigonal planer, trigonal pyramidal,
tetrahedral)
Note: Molecular shape includes only bonds.
 Step
4: Figure out the bond angle (allow for
distortion)
8
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
Possible Electronic Arrangements
9
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
Possible Molecular Arrangements
The names of the shapes of simple molecules and their bond
angles. Lone pairs of electrons are not shown.
10
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
2 Areas of
Electron
Density
No Lone Pairs
Linear
4 Areas
of
Electron
Density
11
No Lone Pairs
Tetrahedral
3 Areas of
Electron
Density
No Lone Pairs
Trigonal Planar
1 Lone Pair
Bent
1 Lone Pair
2 Lone Pairs
Trigonal Pyramidal
Bent
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
5 Areas of
Electron Density
12
No Lone Pairs
Trigonal
Bipyramidal
1 Lone
Pair
Seesaw
2 Lone
Pairs
T-Shaped
3 Lone
Pair
Linear
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
6 Areas of Electron
Density
No Lone
Pairs
Octahedral
3 Lone
Pairs
T-Shaped
13
1 Lone Pair
Square
Pyramidal
2 Lone Pairs
Square Planer
4 Lone Pair
Linear
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)

Step 1: Draw Lewis Structure
CH4
1(C)
4(H)
Total
Valence eWanted e-
Determine number of bonds
𝑤𝑎𝑛𝑡𝑒𝑑−𝑣𝑎𝑙𝑒𝑛𝑐𝑒
# 𝑏𝑜𝑛𝑑𝑠 =
2
Determine number of electrons
# 𝑒 − = 𝑣𝑎𝑙𝑒𝑛𝑐𝑒 − 2 𝑏𝑜𝑛𝑑𝑠
14

Step 2: Determine Electronic Shape

Step 3: Determine Molecular Shape

Step 4: Determine Angle
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)

Step 1: Draw Lewis Structure (Obeys Octet Rule)
SO32-
1(S)
3(O)
2(e-)
Total
Valence eWanted e-
Determine number of bonds
𝑤𝑎𝑛𝑡𝑒𝑑−𝑣𝑎𝑙𝑒𝑛𝑐𝑒
# 𝑏𝑜𝑛𝑑𝑠 =
2
Determine number of electrons
# 𝑒 − = 𝑣𝑎𝑙𝑒𝑛𝑐𝑒 − 2 𝑏𝑜𝑛𝑑𝑠
15

Step 2: Determine Electronic Shape

Step 3: Determine Molecular Shape

Step 4: Determine Angle
Chapter 13: Bonding: General Concepts
Shapes of Molecules (VSEPR)
Student Question
What is the most likely shape of ICl4-?
Helpful Hint: Make sure that your formal
charges are minimized.
a) Octahedral
b) Trigonal Planar
c) Seesaw
d) Tetrahedral
e) None of the Above
16
Chapter 13: Bonding: General Concepts
Polar Molecules
Student Question
Is PCl4- polar or nonpolar?
Helpful Hint: Make sure that your formal
charges are minimized.
a) Polar
b) Nonpolar
17
Chapter 13: Bonding: General Concepts
Take Away From Chapter 13

Big Idea: Bonds are formed from the attraction
between oppositely charged ions or by sharing
electrons. Only the valence electrons participate in
bonding. The shape of the molecules maximize the
distance between areas of high electron density.

Lewis Structures

Be able to draw Lewis structures of covalent
compounds. (57,58)




Know how to calculate formal charges.(78,79)
Identification of most likely Lewis structure.
Know when multiple resonance structures are possible for a
compound.(60,61,65,73)
Know when atoms can expand their octets (group 3 and
greater).(80)
Numbers correspond to end of chapter questions.
18
Chapter 13: Bonding: General Concepts
Take Away From Chapter 13

Shape of Molecules (VSEPR) (88,91)

Know how to determine electronic shape.


Know how to determine molecular shape.



Linear, trigonal planar, tetrahedral, trigonal bipyramidal, or
octahedral.
Linear, angular, trigonal planar, trigonal pyramidal, Tshaped, tetrahedral, seesaw, square planar, trigonal
bipyramidal, square pyramidal, or octahedral.
Know how to determine bond angles.
Polar Molecules

Be able to determine if a molecule is polar or non polar.
(93,94)
Numbers correspond to end of chapter questions.
19
Chapter 13: Bonding: General Concepts