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```					15-1 Dot Diagrams
Dot Diagrams
s1                                        s2p6
H.    s2        s 2p1 s2p2 s2p3 s2p4 s2p5 :He

. X :Be                   .. ..
:X. :C :N :O. :F: :Ne:

:
: :: :
:
.    ..   .
. Al . X. . X. . X: : X. : X :
:

: :
:
X                      .
:

:

:
+1     +2          +3   +4          -3         -2          -1

: :
: :
: :
[x] [x]           [x]     -4   [:x:] [:x:] [:x:]
Ion formation: Loss (oxidation) or gain (reduction) of electrons
A1. NaI
•   Yes, so it is Ionic.
•   Use brackets & charges.
•   (-) ions have 8 dots, (+) ions have 0 dots.

+1      -1
[Na][ I ]
A2. BaO
•   Yes, so it is Ionic.
•   Use brackets & charges.
•   (-) ions have 8 dots, (+) ions have 0 dots.

+2      -2
[Ba ][ O ]
A3. CaF2
•   Yes, so it is Ionic.
•   Use brackets & charges.
•   (-) ions have 8 dots, (+) ions have 0 dots.

-1     +2     -1
[ F ][Ca ][ F ]
A4. K3P
•   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
•   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
• 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
• 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
• 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
• 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
•   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
• 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
•   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
• 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
• 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
• 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+
• 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
H +1      ]
D2. NH4+
• 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-
• 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.
-1

[H O ]
D4. PO4-3
• 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
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.
E1. AlCl3
•   Yes, so it is Ionic.
•   Use brackets & charges.
•   (-) ions have 8 dots, (+) ions have 0 dots.

+3     -1
[ Cl ][Al ][Cl]
-1                        Done!
[ Cl]-1
E4. OCl2
• 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
•   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.
Dot Diagrams Quiz
(Work in Pairs on individual ½ sheets)
Formula          Ionic or     Dot Diagram
Covalent?
(1st element?)
SBr2

AlF3

SiO2
Molecular Names & Formulas Notes

• Molecular compounds are usually
composed of covalently bonded non-
metals.
• Naming molecular compounds utilizes
prefixes which indicate the number of
atoms in each molecule.
• What very common substance is
sometimes called dihydrogen
monoxide?
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     Carbon dioxide
(mono is assumed for the 1st
element)
N2O4    Dinitrogen tetroxide
(the second element always ends
in –ide)
AsBr3   Arsenic tribromide
7F Naming Molecular Compounds
•   1. CO2                   • 7. SiO2 quartz
•   Carbon dioxide           • Silicon dioxide
•   2. NH3 ammonia           • 8. NI3 explodes upon
•   Nitrogen trihydride        pressure
•   3. N2O laughing gas      • Nitrogen tri-iodide
•   Dinitrogen monoxide      • 9. SiBr2
•   4. CCl4 solvent          • Silicon dibromide
•   Carbon tetrachloride     • 10. AsF5
•   5. P2O5                  • Arsenic pentafluoride
•   Diphosphorus pentoxide   • 11. SI4
•   6. SO2 air pollutant     • Sulfur tetraiodide
•   Sulfur dioxide           • 12. CS2 poisonous solvent
• Carbon disulfide
7G Writing Molecular Formulas
•   1. dichlorine monoxide               • 7. carbon(II) oxide
•   Cl2O                                 • (II) indicates +2 charge, so C+2, O-2
•   2. sulfur hexafluoride               • CO
•   SF6                                  • 8. silicon tetrabromide
•   3. silicon trioxide                  • SiBr4
•   SiO3                                 • 9. sulfur trioxide
•   4. dinitrogen pentasulfide           • SO3
•   N2S5                                 • 10. boron trihydride
•   5. nitrogen(III) fluoride            • BH3
•   (III) means +3 charge, so N+3, F-1   • 11. nitrogen(III) hydride
•   NF3                                  • (III) indicates +3, so N+3, H-1 is a
•   6. diphosphorus trioxide               rare form of H
•   P2O3                                 • NH3 is also called ammonia
• 12. diarsenic trisulfide
• As2S3
Compounds Quiz 3

Formula   Bond Type        Name            Structure

Cl       Cl
Carbon
CCl4     Covalent                             C
tetrachloride
Cl       Cl

PbF2       Ionic     Lead(II) fluoride   F- Pb+2 F-

Nitrogen                  I
NI3     Covalent                        I N
tri-iodide                I

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