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Sc 9
Ch 3 Notes – Compounds
Compound: two or more different types of atoms that have CHEMICALLY combined
“Chemically Combined” = form chemical BONDS with each other.
There are TWO types of compounds that can form: covalent and ionic
1.
Covalent Compounds:
-chemically combine by sharing their valence electrons.
This makes them have full valence shells MOST (some) of the time , so that they are energetically more
stable (favourable) (like a noble gas!)
Covalent compounds occur ONLY between
Non-metals and non-metals !!
Example: water!

2
Naming Covalent Compounds .
H
2
O = (water) dihydrogen monoxide
CO
2
= carbon dioxide
CO = carbon monoxide
CO
3
= carbon trioxide
N
2
P
3
= dinitrogen triphosphide
Si
3
S
4
= trisilicon tetrasulphide
Complete the
WS:
Covalent
Compounds
As
5
I
7
= Pentarsenic heptiodide
CCl
4
= carbon tetrachloride
Naming Ionic Compounds And Writing their
Chemical Formula.
Level 1. Simple Ionic compounds
These compounds are formed when a metal chemically combines with a non-metal
To name these, write the chemical name of the metal first, then write the chemical name of the non-metal , but change the ending of the non-metal to “ ide
” .
Don’t worry about the subscripts !
Ex.
NaCl = sodium chloride
Al
2
O
3
= aluminum oxide
MgF
2
= magnesium fluoride
ZrS
2
= zirconium sulphide

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To Write the chemical formula for simple IONIC
compounds, you need to know the combining capacity
(ion charge) of both the metal and the non-metal.
The combining capacities ( ion charge ) tell you how many
BONDS that element can make.
Na +1 can make 1 bonds O -2 can make 2 bonds
When an ionic compound forms, each element must form all the bonds it is able form.
– no bond can be left empty !
Eg. Sodium and oxygen = sodium oxide
Na +1 O -2
= Na
2
O
Aluminum and nitrogen = aluminum nitride
Al +3 N -3
=Al
1
N
1
= AlN

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Magnesium and sulphur = magnesium sulphide
Mg +2 S -2
= Mg
1
S
1
=MgS
Barium and Phosphorous = barium phosphide
Ba +2 P -3
= Ba
3
P
2
Criss-Cross Method – a short cut
Li+1 O-2 Al+3 S-2
Li2 O Al2S3
 Notice that, in the first example, you didn’t have to write the “ one
” down. Notice that you don’t have to write in the positive or negative signs either.
Also note that if you were combining, for example,
Germanium (Ge +4 ) and Sulphur (S -2 ), when you do the
Criss-Cross, you will get: Ge
2
S
4
but this should be reduced to the lowest common factors

Ge
1
S
2
= GeS
2

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Do Practice Problems, Page 86 + Page 87+
WS: LEVEL I
: Ionic Compounds Using Complex Ions
(sometimes called
POLYATOMIC IONS .
There are groups of atoms that like to “hang out” together in a covalent compound. They are named in the table of
COMPLEX IONS at the bottom of the PERIODIC
TABLE.
Notice that the COMPLEX IONS always end with “ ate
” or “ ite
”. There are a few exceptions:
NH
4
+ = ammonium OH = hydroxide
CN = cyanide HS = bisulphide (hydrogen sulphide)
When trying to name compounds, you recognize the complex ions because there will be more than two
types of atoms involved. If you find yourself using three words to name a compound, STOP. Use the
Table of complex ions to find the correct name.

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To name these compounds, simply write the name of the metal first, then the name of the complex ion . You do
NOT have to change the ending or name of the complex ion.
CaCO
3
= calcium carbonate
Mg(OH)
2
= Magnesium hydroxide
AgNO
3
= Silver nitrate
Zr
3
(PO
4
)
4
= Zirconium phosphate
Ba
3
(BO
3
)
2
= Barium borate
ZnCrO
4
= Zinc Chromate
In
5
(P
3
O
10
)
3
= Indium tripolyphosphate
Writing Chemical Formula for Complex Ions ( still
LEVEL II)
Follow the same method used for simple (level 1) ionic compounds. However, DO NOT change the endings on the complex ions – they always stay the same .
If you need more than one molecule of the complex ion in a compound, use brackets around the complex ion.
Ex.

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Aluminum and sulphate = aluminum sulphate
Al +3 SO
4
-2
=Al
2
(SO
4
)
3
Ammonium and hydroxide = ammonium hydroxide
NH
4
+1 OH -1
=NH
4
OH
Scandium and phosphate = scandium phosphate
Sc +3 PO
4
-3
= ScPO
4
Silver and chlorite = silver chlorite
Ag +1 ClO
2
-1
= AgClO
2
Do: Practice Problems, Page 91 + WS: Level II + Reading Check, Page 92
Level 3: Using Roman numerals.

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
Some elements are able to form more than one kind of ion (that is, they have different combining capacities
(ion charges)

For example, Fe has a combining capacity of 3+
or 2+ . It can form compounds with chlorine that have the formula of either FeCl
3
or FeCl
2
.

When the elements that have more than one combining capacity (ionic charge) are in compounds, their combining capacity for that compound is listed in roman numerals , in brackets , after that element.
 e.g. PbCl4 .= lead (IV) chloride

There are several methods used to correctly assign the roman numeral to a chemical name, but ALL of the methods start with examining the chemical symbol on the periodic table and looking up the combining capacities (ion charges) of the elements or complex ions in the compound.

Examples:

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SnBr
4
= Tin (IV) bromide
Hg(OH)
2
= mercury (II) hydroxide
Os
3
(BO
3
)
4
= osmium (IV) borate
Pt
2
O = Platinum (I) oxide
DO: P DO: Practice Problems, Page 89 + Page 90 + Worksheet: Level III

COVALENT COMPOUNDS WS
:
Write the name or formula of the following
Chemical Formula Chemical Name
CF
CO
4
2
N
2
Cl
4
SO
2
CO
CO
3
Se
3
I
4z
Carbon tetra fluoride
Carbon dioxide
Dinitrogen tetrachloride
Sulphur dioxide
Carbon monoxide
Carbon trioxide
N
2
O
5
PCl
S
4
Cl
3
Dinitrogen pentoxide
Phosphorous monochloride
10

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Level I: Simple Ionic Compounds
Write the names for these compounds:
1.
Na Br sodium bromide
2.
Al
2
S
3
Aluminum sulphide
3.
CaCl
2
Calcium chloride
4.
BeF
2
Beryllium fluoride
5.
MgCl
2
Magnesium chloride
6.
K
2
O Potassium oxide
7.
Sr
3
N
2
Strontium nitride
8.
LiI Lithium Iodide
9.
Fr
3
P Francium Phosphide
10.ZrAt
4
Zirconium Astatide
Write the formula for these compounds:
1.
Sodium oxide Na
2
O
2.
Calcium fluoride CaF
2
3.
Magnesium sulphide MgS
4.
lithium nitride Li
3
N
5.
Aluminum oxide Al
2
O
3
6.
Cesium phosphide Ce
7.
barium iodide BaI
2
8.
Lutetium arsenide
9.
Tungsten chloride WCl
6
10.Zinc astatine Zn

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LEVEL II: Ionic Compounds with Complex Ions
Name the following compounds:
Formula Chemical Name
NaOH Sodium hydroxide
Li
2
SO
4
Lithium Sulphate
Mg
3
(BO
3
)
2
KCN
Magnesium borate
Potassium cyanide
AgNO
3
Silver nitrate
CaCO
3
Calcium carbonate
Al(C
5
H
8
NO
4
)
3
Aluminum glutamate
NaHCO
3
Sodium bicarbonate OR Sodium hydrogen carbonate
Be
3
(PO
4
)
2
Beryllium phosphate
Sr(SCN)
2
Stronium thiocyanate
Write the Chemical Formula for the Following Compounds using complex Ions:
Chemical Name Chemical Formula
Rubidium phosphate Rb
3
PO
4
Silver nitrate AgNO
3
Calcium nitrite Ca(NO
2
)
2
Ammonium permanganate NH
4
MnO
4
Tungsten silicate W(SiO
3
)
3
Barium bisulphate Ba(HSO
4
)
2
Hafnium oxalate Hf(OOCCOO)
2
Tantalum dihydrogen phosphate
Lawrencium dichromate
Ta(H
Lr
2
2
(Cr
PO
2
O
4
7
)
)
5
3
Zinc stearate Zn (C
17
H
35
COO)
2

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Level III – Chemical Formula Using Roman Numerals
Name the following compounds:
1.
PoF
4
Polonium IV fluoride
2.
Tl
2
O Thallium I oxide
3.
NbP Niobium III phosphide
4.
Ir
3
N
4
Iridium IV nitride
5.
MnBr
3
Manganese III bromide
6.
Au
3
P Gold I phosphide
7.
PtO
2
Platinum IV oxide
8.
OsI
4
Osmium IV iodide
9.
CrS Chromium II sulphide
10.Fe
2
O
3
Iron III oxide
Give the chemical formula of the following compounds
:
1.
Titanium III phosphide TiP
2.
Vanadium II oxide VO
3.
Molybdenum III sulphide MoS
4.
Manganese IV bromide MnBr
4
5.
Copper I nitride Cu
3
N
6.
Palladium IV iodide PdI
4
7.
Rhenium VII nitride Re
3
N
7
8.
Rhodium III nitride RhN
9.
Gold III phosphide Au
3
P
3
10.
Nickel II Oxide NiO

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