DATE ___________________
NOTES-031
CHEM 110 (BEAMER)
xNOTES-31:x Lewis Dot Structures-02
Lewis Dot Structures of Covalent Compounds
I.
Covalent Compounds (review)
Note: Take out your Periodic Tables. You will need them throughout the lecture.

Covalent compounds are composed only from

PRACTICE PROBLEMS:

Circle only the covalent compounds below.

Assume metalloids (semi-metals) in the following problems behave like non-metals.
CCl4
HBr
Na2SO4
FeO
C12H22O11
SO3
AsF3
H2O
N2O5
in

share
to attain a
.

Period 1: Full Valence Shell =

All other elements: Full Valence Shell =
, often called the
.
_________________ atoms

EXAMPLE:
CH4
_________________ atoms

EXAMPLE:
SeBr2
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DATE ___________________
II.
NOTES-031
CHEM 110 (BEAMER)
Rules for Drawing Lewis Structures:

Note:
There are LOTS of rules. These need to be memorized. And you must be able to apply
them at a moment’s notice.

Note:
Work Horses (you know who you are): I would re-type these rules so that they all fit on one page.

Note:
Always keep these rules at your side while drawing Lewis Structures until Friday.
1)
Count the total number of electrons. Your final structure should have the same number of electrons.
2)*
is always a
atom.
3)*
is NEVER a
atom.
4)*
Carbon
5)*
ABSOLUTELY NO
has a total of
until CHEM 120. They tend to
Examples
*
6)
Except for
the
is usually the
.
7)
, they are usually
If there is
.
Example: C2F2H4
Total # of e–:
vs
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DATE ___________________
8)
NOTES-031
Carbon
CHEM 110 (BEAMER)
has
.
Total # of e–:
Example: CNH5
vs

PRACTICE PROBLEMS:
NH3

EXAMPLE:
Total # e–:
C2H6

EXAMPLE:
Total # e–:
C2H6O

EXAMPLE:
Total # e–:
C3H7Br

EXAMPLE:
Total # e–:
N2H4

EXAMPLE:
Total # e–:
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DATE ___________________
NOTES-031
CHEM 110 (BEAMER)
.
III.
Rules for Drawing Lewis Structures:
9)
If single bonds “don’t work,”: double, triple up, or two doubles.
O2

EXAMPLE:
Total # e–:
N2

EXAMPLE:
Total # e–:
CH2O

AYD1:
Total # e–:
HCN

AYD1:
Total # e–:
10)*

11)
EXAMPLES OF
NO-NO’S:
When given a choice of where to put
, the element
gets the most lone pair, and
gets the most lone pairs.
Example: CH3NO
vs
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DATE ___________________
12)
NOTES-031
CHEM 110 (BEAMER)
Get over “American Sharing.”
CO

EXAMPLE:
Total # e–:
O3

AYD1:
Total # e–:
IV.
Rules for Drawing Lewis Structures:

An
is a particle where

Ions have
13)
If an ion is
indicated by
remove any
anywhere in the structure that will make the structure “work.”
OH1–

EXAMPLE:
or
OH–
# of e–:
14)
If an ion is
add any
anywhere in the structure that will make the structure “work.”
NH41+

EXAMPLE:
or
NH4+
# of e–:
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DATE ___________________

A
NOTES-031
is a
in which a total of
between

A
.
is a
in which a total of
between

A
CHEM 110 (BEAMER)
.
is a
in which a total of
between
.

Again:

Bond Length:



Bond Strength:


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