Transcript Deducing Formula of Ionic Compounds

Ionic Bonding
Learning Objectives
• Describe the formation of ions by the loss/gain of
electrons.
• Describe the formation of ionic bonds using ‘dot
and cross’ diagrams.
• Predict the structure and properties of ionic
compounds.
It is the way in which atoms join
together with each other.
Stability of Atoms

full
Have a _______
outermost shell of
electrons, like that of noble gases.
This means that the
electron shell is
completely filled.
Stability of Atoms

The atoms achieve this either by:
(a) by gaining or losing electrons
(b) by sharing electrons
Stability of Atoms

lose
Metals (Group I to Group III) ________
cations
electrons to form _____________.

Non- metals (Group IV to Group VII)
gain
anions
________
electrons to form ________.
Stability of Atoms


Metallic
______________
atoms tend to achieve
stable noble gas electronic configuration
lose
by __________
electrons to form
cations
_________________.
Non-Metallic
______________
atoms tend to achieve
stable noble gas electronic configuration
gain
by _______
electrons to form
___________________.
anions
Formation of Ions
Electrons are transferred from the
metal atom to the non-metallic atom.
 The oppositely- charged ions are
attracted to one another to form an
ionic compound.
 The strong electrostatic attraction
between cations and the anions which
holds the two ions together is an ionic
bond.

Positive Ions

1 (a) Use the Periodic Table to
state the electronic structure of
magnesium and of chlorine.
Magnesium atom, Mg
2.8.2
chlorine atom, Cl
2.8.7
Practice Question

1 (b) Magnesium chloride contains
magnesium ions and chloride ions. Give
the electrical charges on these ions
and explain how these ions are
formed from their atoms.

Electrical charge on magnesium ion is
2+.

Electrical charge on chloride ion is 1-
Positive Ions

Magnesium ion is formed when a magnesium
atom loses 2 valence electrons to atoms chlorine
to achieve stable noble gas configuration.
2+
Magnesium atom, Mg
2.8.2
Magnesium ion, Mg2+
2.8
Negative Ions

Chloride ion is formed when the
chlorine atom gains 1 valence electron
from magnesium atoms to achieve
stable noble gas configuration.
-
chlorine atom, Cl
chloride ion, Cl-
Practice Question

Describe, using one suitable example,
the formation of ionic bonds between
metallic and non-metallic elements.

A suitable example of an ionic
compound is sodium chloride.

Sodium atom, which is a metal, will
lose its one valence electron to
chlorine atom to achieve stable noble
gas configuration. Positive sodium ion
is formed.
Practice Question

Describe, using one suitable example,
the formation of ionic bonds between
metallic and non-metallic elements.

Chlorine atom, which is a non-metal,
will gain one valence electron from
sodium atom to achieve stable noble
gas configuration. Negative chloride
ion is formed.
Practice Question

Describe, using one suitable example,
the formation of ionic bonds between
metallic and non-metallic elements.

The electrostatic forces of attraction
between the positive sodium ions and
negative chloride ions is the ionic
bond.
Formation of Ionic Bond in
Sodium Chloride
Na
-
+
+
Na
Cl
Cl
Electron of sodium
Electron of chlorine
Deducing Formula of Ionic Compounds
– the “criss-cross” method.
----------------------------------------------------------------------
Example 1: Sodium chloride
We are only interested in the
charge numbers NOT the
sign of the charge.
Na +
Cl-
Na1
Cl1
We cross the charge numbers
ONLY.
 Ionic formula of sodium chloride is NaCl.
Deducing Formula of Ionic Compounds
– the “criss-cross” method.
----------------------------------------------------------------------
Example 2: Magnesium chloride
The charge number of magnesium ion
is 2. Therefore, the number 2 is
crossed over to Cl.
Mg 2+
Cl-
Mg1
Cl2
The charge number of chloride ion is
1, and it is crossed over to Mg.
We ignore the plus or minus.
 Ionic formula of magnesium chloride is MgCl2.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
cation
F-
Cl-
I-
Na+
K+
H+
NH4+
Ba2+
Note: * Some of these compounds DO NOT exist.
NO3-
OH-
Using the table given, deduce the formula of the ionic compounds
formed.
anion
F-
Cl-
I-
NO3-
OH-
Na+
NaF
NaCl
NaI
NaNO3
NaOH
K+
KF
KCl
KI
KNO3
KOH
H+
HF
HCl
HI
HNO3
H2O
NH4+
NH4F
NH4Cl
NH4I
Ba2+
BaF2
BaCl2
BaI2
cation
Note: * Some of these compounds DO NOT exist.
NH4NO3 NH4OH
Ba(NO3)2
Ba(OH)2
Using the table given, deduce the formula of the ionic compounds
formed.
anion
cation
O2-
SO42-
CO32-
Na+
K+
H+
NH4+
Ba2+
Note: * Some of these compounds DO NOT exist.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
cation
O2-
SO42-
CO32-
Na+
Na2O
Na2SO4 Na2CO3
K+
K2O
K2SO4
K2CO3
H+
H2O
H2SO4
H2CO3
NH4+
(NH4)2O
Ba2+
BaO
(NH4)2SO4 (NH4)2CO3
BaSO4
BaCO3
Note: * Some of these compounds DO NOT exist.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
cation
F-
Cl-
I-
Zn2+
Ca2+
Mg2+
Pb2+
Cu2+
Note: * Some of these compounds DO NOT exist.
NO3-
OH-
Using the table given, deduce the formula of the ionic compounds
formed.
anion
F-
Cl-
I-
NO3-
OH-
Zn2+
ZnF2
ZnCl2
ZnI2
Zn(NO3)2
Zn(OH)2
Ca2+
CaF2
CaCl2
CaI2
Ca(NO3)2
Ca(OH)2
Mg2+
MgF2
MgCl2
MgI2
Mg(NO3)2
Mg(OH)2
Pb2+
PbF2
PbCl2
PbI2
Pb(NO3)2
Pb(OH)2
Cu2+
CuF2
CuCl2
CuI2
Cu(NO3)2
Cu(OH)2
cation
Note: * Some of these compounds DO NOT exist.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
cation
O2-
SO42-
CO32-
Zn2+
Ca2+
Mg2+
Pb2+
Cu2+
Note: * Some of these compounds DO NOT exist.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
O2-
SO42-
CO32-
Zn2+
ZnO
ZnSO4
ZnCO3
Ca2+
CaO
CaSO4
CaCO3
Mg2+
MgO
MgSO4 MgCO3
Pb2+
PbO
PbSO4
PbCO3
Cu2+
CuO
CuSO4
CuCO3
cation
Note: * Some of these compounds DO NOT exist.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
cation
F-
Cl-
I-
Fe2+
Al3+
Fe3+
Note: * Some of these compounds DO NOT exist.
NO3-
OH-
Using the table given, deduce the formula of the ionic compounds
formed.
anion
F-
Cl-
I-
NO3-
OH-
Fe2+
FeF2
FeCl2
FeI2
Fe(NO3)2
Fe(OH)2
Al3+
AlF3
AlCl3
AlI3
Al(NO3)3
Al(OH)3
Fe3+
FeF3
FeCl3
FeI3
Fe(NO3)3
Fe(OH)3
cation
Note: * Some of these compounds DO NOT exist.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
cation
O2-
SO42-
CO32-
Fe2+
Al3+
Fe3+
Note: * Some of these compounds DO NOT exist.
Using the table given, deduce the formula of the ionic compounds
formed.
anion
O2-
SO42-
CO32-
Fe2+
FeO
FeSO4
FeCO3
Al3+
Al2O3
Al2(SO4)3 Al2(CO3)3
Fe3+
Fe2O3
Fe2(SO4)3 Fe2(CO3)3
cation
Note: * Some of these compounds DO NOT exist.
Write down the formulae for these ions
1. Magnesium ion
2. Zinc ion
3. Iron (III) ion
4. Carbonate ion
5. Nitrate ion
6. Ammonium ion
7. Sulfide ion
8. Sulfate ion
9. Hydrogen ion
10. Silver ion
Prepared by Miss Geraldine Oh
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Write down the name of these ions
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•
•
•
•
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N3OHO2IMnO4Ba2+
Prepared by Miss Geraldine Oh
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• Write down 3 formulae using the ions u
have written so far.
Prepared by Miss Geraldine Oh
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