Supplemental packet page 66
Lewis Dot Structures
Dr.Gergens - SD Mesa College
Things to keep in mind when
drawing Lewis structure
1. Always count
valence electrons
2. Know the preferred number
of bonds to these elements
CNOFH
4 3 211
3. N O , these elements may have (2) (1)
a variable number of bonds
(4) (3)
4. If the substance has hydrogen list first in its formula:
a. the substance is characterized as an acid
b. the H is bound to oxygen in the substance’s structure
5. F O N Cl Br I S C H for determining bond polarity
F O N Cl Br I S C H for determining
bond polarity between nonmetal atoms
Large difference in electronegativity between H—F most polar bond
between C—F very polar bond
F O N Cl Br I S C H
Little difference in electronegativity
Less polar
Between identical atoms, C-C, F-F bonding is nonpolar
1.
Calculate
2.
Assemble
3.
Connect the other atoms to the central
Each line represents
a single bond made
shared between two atoms.
4.
Give the outer
paired electrons.
5.
the total number
the bonding
most
of valence
framework.
atoms,
EXCEPT for hydrogen,
sets
of
1C • 4
4H•1
= 4
= 4
+
VE = 8
Add missing
7.
Apply the octet rule to check to see that each atom has eight
electrons surrounding it.
9.
three
Count valence electrons
in your provisional
structure.
valence electrons
calculate in step 1 are present.
electrons
group
#
by drawing a single line.
up of two electrons
being
6.
8.
CH4
electrons.
to the central
atom.
Share neighboring electrons by moving electrons to satisfy the
octet about each atom.
Place a bracket around ions, followed by ion charge.
See if all
H
H
C
H
H
1.
Calculate
the total number
2.
Assemble
3.
Connect the other atoms to the central
Each line represents
a single bond made
shared between two atoms.
the bonding
most
of valence

NH4
electrons.
framework.
4.
Give the outer
paired electrons.
5.
Count valence electrons
in your provisional
structure.
valence electrons
calculate in step 1 are present.
EXCEPT for hydrogen,
6.
Add missing
7.
Apply the octet rule to check to see that each atom has eight
electrons surrounding it.
8.
Share neighboring electrons by moving electrons to satisfy the
octet about each atom.
9.
electrons
atoms,
by drawing a single line.
up of two electrons
being
to the central
atom.
Place a bracket around ions, followed by ion charge.
three
sets
of
group
#
1N • 5
= 5
4H•1
= 4
+ 1 
= -1
VE = 8
See if all

H
H
N
H
HH
1.
Calculate
the total number
2.
Assemble
3.
Connect the other atoms to the central
Each line represents
a single bond made
shared between two atoms.
the bonding
most
of valence
electrons.
BH3
framework.
4.
Give the outer
paired electrons.
5.
Count valence electrons
in your provisional
structure.
valence electrons
calculate in step 1 are present.
6.
Add missing
7.
Apply the octet rule to check to see that each atom has eight
electrons surrounding it.
electrons
atoms,
by drawing a single line.
up of two electrons
being
EXCEPT for hydrogen,
to the central
three
sets
of
group
#
1B • 3
4H•1 = 4
+ 1
=
1
VE = 8
See if all
H
atom.
H
8.
9.
Share neighboring electrons by moving electrons to satisfy the
octet about each atom.
Place a bracket around ions, followed by ion charge.
= 3
B
H
H
1.
Calculate
2.
Assemble
3.
Connect the other atoms to the central
Each line represents
a single bond made
shared between two atoms.
Give the outer
paired electrons.
most
electrons.
CO2
framework.
atoms,
by drawing a single line.
up of two electrons
being
EXCEPT for hydrogen,
three
Count valence electrons
in your provisional
structure.
valence electrons
calculate in step 1 are present.
6.
Add missing
to the central
atom.
of
= 4
2O•6
= 12
+
Apply the octet rule to check to see that each atom has eight
electrons surrounding it.
8.
Share neighboring electrons by moving electrons to satisfy the
octet about each atom.
Place a bracket around ions, followed by ion charge.
See if all
••
OO
O
••
••
••
••
7.
9.
sets
1C • 4
VE = 16
5.
electrons
group
#
C
C
••
••
••
OOO
••
••
••
••
••
••
the bonding
of valence
••
••
••
4.
the total number
Calculate
the total number
2.
Assemble
3.
Connect the other atoms to the central
Each line represents
a single bond made
shared between two atoms.
NO2
framework.
5.
Count valence electrons
in your provisional
structure.
valence electrons
calculate in step 1 are present.
6.
Add missing
7.
Apply the octet rule to check to see that each atom has eight
electrons surrounding it.
8.
Share neighboring electrons by moving electrons to satisfy the
octet about each atom.
to the central
atom.
Place a bracket around ions, followed by ion charge.
three
sets
of
= 5
2 O • 6 = 12
–
+ 1e
= 1
VE = 18
See if all
••
••
EXCEPT for hydrogen,
1N • 5
••
••
O
O
O
OO
••
••
••
••
••
••
••
••
Give the outer
paired electrons.
electrons
atoms,
group
#
by drawing a single line.
up of two electrons
being
4.
9.
most
electrons.
••
••
the bonding
of valence
••
••
••
•• ••
••
••
O
N
O
NN
O
N ••
OO
••
••
••
••
••
••
••
••
••
1.
valence shell electron
pair repulsion
VSEPR = ________ ________ ________ ________ ________
Deter mi ne the angl es between bonds, name the g eometry about the central atom and g ive the its hybridizati on.
Ideal bonding for carbon is Four bonds to carbon - Four bonding modes
Ide al Ge om e tr ie s
109.5
109.5
H C H
bond angles
g eometr ic name
H
H
120C
120
120
H 120 H
109.5 H109.5
H
tetrahedral
C
180
H
trigonal planar
C
C H
linear
O
180
C O
linear
Ideal bonding angles for carbon
Non-Ide al Ge om e tr ie s
:
:
:
bond ang les
g eometr ic name
H
N
H
107.5 H107.5
pyramidal or
trigonal pyramid
N
H
q<120
bent
:
O
H
104.5
H
g eometr ic name
bent
O
:
:
N
N
H
:
bond ang les
:
N
C
Bond angles for non-ideal geometries
are less than an ideal angle in ideal for C.
H This is because an electron pair
1) occupies a lot of space &
2) is held close to nucleus of central atom
H
supplemental HO 70
1.
Calculate
2.
Assemble
3.
Connect the other atoms to the central
Each line represents
a single bond made
shared between two atoms.
4.
Give the outer
paired electrons.
5.
Count valence electrons
in your provisional
structure.
valence electrons
calculate in step 1 are present.
6.
Add missing
7.
Apply the octet rule to check to see that each atom has eight
electrons surrounding it.
8.
Share neighboring electrons by moving electrons to satisfy the
octet about each atom.
9.
the total number
the bonding
most
electrons
of valence
electrons.
framework.
atoms,
by drawing a single line.
up of two electrons
being
EXCEPT for hydrogen,
to the central
atom.
Place a bracket around ions, followed by ion charge.
three
sets
of
See if all