DOT DIAGRAMS
BOND CLASSIFICATION BY EN DIFFERENCE
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Tape this chart into your
cornell notes under the
heading above
Understanding this
table is KEY
DMA # 20, TUESDAY 1/18
Take out your large periodic table for
today’s DMA and class.
Compound
MnO2
O2
MgO
KCl
CH4
Type of
Compound
- Ionic
- Covalent
- Metallic
EN Difference
Type of Bond
-Ionic
-Non Polar
Covalent
-Polar Covalent
Electrons:
-Transferred
-Shared
Equally
-Shared
Unequally
DMA # 20, TUESDAY 1/18
Take out your large periodic table for
today’s DMA and class.
Compound
MnO2
O2
MgO
KCl
CH4
Type of
Compound
- Ionic
- Covalent
- Metallic
EN Difference
Type of Bond
-Ionic
-Non Polar
Covalent
-Polar Covalent
Electrons:
-Transferred
-Shared
Equally
-Shared
Unequally
LEWIS STRUCTURES

What are they?

Lewis structures use
dots to represent the
valence electrons
involved in bonding and
lines to represent bonds.
LEWIS STRUCTURE RULES…
In general, Elements share or transfer electrons to reach nearest noble gas e-config

Hydrogen gains an electron to become like Helium (1s2). No more than 2
electrons around elements H and He! (DUET RULE)

2nd period elements may lose electrons to become like Helium or gain
electrons to become like Neon. No more than 8 electrons around any
element in period 2! (OCTET RULE)
Exceptions:

Be and B can have LESS than 8 electrons around them…(example: BF3)

3rd period elements can have MORE than 8 electrons if they need to
because of extra d orbital to place them in (3s23p63d10)…(example PCl5)
A1. NAI
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Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots.
+1
-1
[Na][ I ]
A2. BAO
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Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots.
+2
-2
[Ba ][ O ]
A3. CAF2




Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots.
-1
+2
-1
[ F ][Ca ][ F ]
A4. K3P




Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots.
+1
-3
+1
[ K ] [ P ][ K ]
+1
[K]
B1. H2



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If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 2.
Place 2 dots between each adjacent atoms to bond them.
H H
B2. CL2





If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each Cl has 7 electron for a total of 14.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the
4 sides of each atom.
Cl Cl
Each atom has a complete octet (8).
B3. H2S
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If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 2. A S atom has 6. The
total is 8 dots.
Place 2 dots between each adjacent atoms to bond them.
Hydrogens only need 2 dots, other non-metals need 8.
Place the remaining dots in pairs symmetrically around the
4 sides of each atom.
H S H
Each atom has an octet (8) or complete valence shell.
B4. OF2
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If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each F has 7 electrons for a total of 14. An O atom has 6.
The total is 20 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the
4 sides of each atom.
F O F
Each atom has a complete octet (8).
B5. NH3
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
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If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 3. An N atom has 5.
The total is 8 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
H N H
H
B6. PCL3








If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each Cl has 7 electrons for a total of 21. A P atom has 5.
The total is 26 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the 4 sides of
each atom.
Cl P Cl
Cl
B7. CH4
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
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If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 4. An C atom has 4.
The total is 8 dots.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
H
H C H
H
B8. CH3I
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If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each H has 1 electron for a total of 3. An C atom has 4.
An iodine has 7 dots. The total is 14 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the 4 sides of
each atom.
I
H C H
H
C1. O2
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Each O has 6 electron for a total of 12 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4
sides of each atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or
triple bonds
O O
Now each atom has an octet (8) of valence electrons.
C2. CO2
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
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Each O has 6 electron for a subtotal of 12. The C has 4 for
a grand total of 16 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4
sides of each atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or
triple bonds
O C O
Double bonds give each atom 8 electrons.
C3. C2H2
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Each C has 4 electron for a subtotal of 8. Each H has 1 for a
grand total of 10 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4
sides of each atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or triple
bonds
H C C H
A triple bond in needed so each atom has 8 electrons.
D1. H3O+
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Each H has 1 electron for a subtotal of 3. An O has 6.
A positive charge means 1 electron is missing. (Negative
charge indicates extra electrons.)
The total is 8 dots.
O has to be central. H’s can only make 1 bond.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place in brackets & label the charge.
[
]
H O H
+1
H
D2. NH4+
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Each H has 1 electron for a subtotal of 4. An N has 5.
A positive charge means 1 electron is missing. (Negative
charge indicates extra electrons.)
The total is 8 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place in brackets & label the charge.
[ ]
H +1
H N H
H
D3. OH
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The H has 1 electron. An O has 6.
A negative charge means there is 1 extra electron. (Positive
charge indicates missing electrons.)
The total is 8 dots.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the
4 sides of each atom.
Place in brackets & label the charge.
[H O ]
-1
D4. PO4-3
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Each O has 6 electrons for 24. A P atom has 5.
A negative 3 charge means 3 extra electrons. (Negative charge
indicates extra electrons.) The total is 32 dots.
The 1st atom is usually central.
Place 2 dots between each adjacent atoms to bond them.
H only requires 2 dots. Other atoms require 8 dots.
Place the remaining dots in pairs symmetrically around the 4 sides of
each atom.
Place in brackets & label the charge.
[ ]
O -3
O P O
O
E1. ALCL3
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

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Does it start with a metal?
Yes, so it is Ionic.
Use brackets & charges.
(-) ions have 8 dots, (+) ions have 0 dots.
+3
-1
[ Cl ][Al ][Cl]
[ Cl]
-1
-1
Done!
E4. OCL2
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




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If it doesn’t start with a metal, it’s covalent.
Count the number of total valence electrons.
Each Cl has 7 electrons for a total of 14.
An O atom has 6.
The total is 20 dots.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the
4 sides of each atom.
Cl O Cl
Each atom has a complete octet (8).
E8. HCN
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H is a non-metal so this is covalent.
Add up the valence electron dots for each atom.
The C has 4 electrons.
The N has 5 dots.
The H has 1 for a grand total of 10 dots.
The 1st atom is usually central, but H can only make 1 bond.
The C is then central.
Place 2 dots between each adjacent atoms to bond them.
Place the remaining dots in pairs symmetrically around the 4 sides of each
atom.
H only requires 2 dots. Other atoms require 8 dots.
If you are short, move pairs in between to make double or triple bonds
H C N
A triple bond in needed so the C & N each have 8 electrons.
SCHEDULE OF WEEK 1/22-25/08
Monday – MLK Day
Tuesday – Dot Diagram Quiz / Molecular Names &
Formulas / Asmt: 7F & 7G all
Wednesday – Molecular Shapes & Polarity 15-3 &
15-4
Thursday – Quiz / Organic Names & Structures /
Asmt: A-H
Friday – Review Organics / Practice Exam
REVIEW EXAMPLES
E1 – AlCl3
 E4 – OCl2
 E8 – HCN
 Get out your periodic table & dot diagram
handout.

DOT DIAGRAMS QUIZ
(WORK IN PAIRS ON INDIVIDUAL ½ SHEETS)
Formula
SBr2
AlF3
SiO2
Ionic or
Covalent?
(1st element?)
Dot Diagram
MOLECULAR NAMES & FORMULAS NOTES
Molecular compounds are usually
composed of covalently bonded nonmetals.
 Naming molecular compounds utilizes
prefixes which indicate the number of
atoms in each molecule.
 What very common substance is
sometimes called dihydrogen monoxide?
 Answer: H2O

PREFIXES FOR MOLECULAR NAMING
1
Mono
6
Hexa
2
Di
7
Hepta
3
Tri
8
Octa
4
Tetra
9
Nona
5
Penta
10
Deca
EXAMPLES:
CO2
N2O4
AsBr3
Carbon dioxide
(mono is assumed for the 1st
element)
Dinitrogen tetroxide
(the second element always ends
in –ide)
Arsenic tribromide
7F NAMING MOLECULAR COMPOUNDS
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1. CO2
Carbon dioxide
2. NH3 ammonia
Nitrogen trihydride
3. N2O laughing gas
Dinitrogen monoxide
4. CCl4 solvent
Carbon tetrachloride
5. P2O5
Diphosphorus pentoxide
6. SO2 air pollutant
Sulfur dioxide
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7. SiO2 quartz
Silicon dioxide
8. NI3 explodes upon
pressure
Nitrogen tri-iodide
9. SiBr2
Silicon dibromide
10. AsF5
Arsenic pentafluoride
11. SI4
Sulfur tetraiodide
12. CS2 poisonous solvent
Carbon disulfide
7G WRITING MOLECULAR FORMULAS
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1. dichlorine monoxide
Cl2O
2. sulfur hexafluoride
SF6
3. silicon trioxide
SiO3
4. dinitrogen pentasulfide
N2S5
5. nitrogen(III) fluoride
(III) means +3 charge, so N+3, F-1
NF3
6. diphosphorus trioxide
P2O3
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7. carbon(II) oxide
(II) indicates +2 charge, so C+2, O-2
CO
8. silicon tetrabromide
SiBr4
9. sulfur trioxide
SO3
10. boron trihydride
BH3
11. nitrogen(III) hydride
(III) indicates +3, so N+3, H-1 is a rare
form of H
NH3 is also called ammonia
12. diarsenic trisulfide
As2S3
COMPOUNDS QUIZ 3
Formula
Bond Type
Name
CCl4
Covalent
Carbon
tetrachloride
PbF2
Ionic
Lead(II) fluoride
Covalent
Nitrogen
tri-iodide
NI3
Structure
Cl
Cl
C
Cl
Cl
F- Pb+2 FI N
I
I