Periodic Table Study Guide
How to Draw Lewis
Structures
LewisStructures
1)  Findyourelementontheperiodictable.
2)  Determinethenumberofvalenceelectrons.
3)  Thisishowmanyelectronsyouwilldraw.
LewisStructures
•  Findoutwhichgroup
(column)yourelementis
in.
•  Thiswilltellyouthe
numberofvalence
electronsyourelement
has.
•  Youwillonlydrawthe
valenceelectrons.
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Groups-Review
Group1=1electron
Group2=2electrons
Group8=8electrons
ExceptforHe,ithas2
electrons
• Each column is
called a “group”
• Each element in a
group has the same
number of electrons
in their outer orbital,
also known as
“shells”.
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• Theelectronsinthe
outershellarecalled
“valenceelectrons”
The4steps
•  Step1:Calculatethenumberofavailablevalenceelectrons.
•  ForeachposiIvecharge,subtract1fromthenumberofvalence
electrons.
•  ForeachnegaIvecharge,add1tothenumberofvalence
electrons.
•  Step2:IdenIfythecentralatomastheleastelectronnegaIve
atom,EXCLUDINGH.
•  Step3:Drawbondsbetweenatoms.(eachbondrequires2
electrons)
•  Step4:DrawremainingelectronsaslonepairstosaIsfyoctetrules.
•  Forions,drawsquarebracketsandaddthetotalcharge.
Example1:Methanol(CH3OH)
• 
• 
• 
• 
• 
Step1:
4Hx1valenceelectron=4valenceelectrons
1Cx4valenceelectrons=4valenceelectrons
1Ox6valenceelectrons=6valenceelectrons
Totalvalenceelectrons=14valenceelectrons
Example1:Methanol(CH3OH)
•  Step2:
•  FindtheleastelectronegaIveatomthatisnoH.In
thiscaseCisfurtherfromFthanOsoCwillbeour
centralatom.
Example1:Methanol(CH3OH)
•  Step3:Addbondsbetweenatoms.Checkingtomake
surethateachatomhasmadeallofitsbonds.
Remembereachbondtakes2electrons.
Example1:Methanol(CH3OH)
•  Step4:Drawremainingelectronsaslonepairsto
saIsfyoctetrules.
•  Totalof5bonds=10electronsused
•  14-10=4electronsremaining
•  →2lonepairsavailable
Example2:Hypochloriteion(ClO )
•  Trythisonyourown.
Example2:Hypochloriteion(ClO )
LewisStructures
1)  Writetheelement
symbol.
2)  Carbonisinthe4th
group,soithas4
valenceelectrons.
3)  StarIngattheright,
draw4electrons,or
dots,counterclockwisearoundthe
elementsymbol.
LewisStructures
1)  Checkyourwork.
2)  Usingyourperiodic
table,checkthat
Carbonisinthe4th
group.
3)  Youshouldhave4
totalelectrons,or
dots,drawninfor
Carbon.
LewisStructures
Trytheseelementsonyour
own:
a) 
b) 
c) 
d) 
e) 
f) 
H
P
Ca
Ar
Cl
Al
LewisStructures
Trytheseelementsonyour
own:
a) 
b) 
c) 
d) 
e) 
f) 
H
P
Ca
Ar
Cl
Al
LewisStructures
Trytheseelementsonyour
own:
a) 
b) 
c) 
d) 
e) 
f) 
H
P
Ca
Ar
Cl
Al
LewisStructures
Trytheseelementsonyour
own:
a) 
b) 
c) 
d) 
e) 
f) 
H
P
Ca
Ar
Cl
Al
LewisStructures
Trytheseelementsonyour
own:
a) 
b) 
c) 
d) 
e) 
f) 
H
P
Ca
Ar
Cl
Al
LewisStructures
Trytheseelementsonyour
own:
a) 
b) 
c) 
d) 
e) 
f) 
H
P
Ca
Ar
Cl
Al
LewisStructures
Trytheseelementsonyour
own:
a) 
b) 
c) 
d) 
e) 
f) 
H
P
Ca
Ar
Cl
Al
EndofStudyGuide.