The document discusses ionic compounds, explaining the nature of ions, including cations and anions, and their formation, as well as the octet rule. It covers concepts related to ionic bonding, properties of binary ionic compounds, and the significance of polyatomic ions and oxidation numbers. Additionally, it touches upon ionic compounds in relation to hydrates and silicates.

1. Ionic Compounds
Ionic Compounds
Chapter 5
Chapter 5

2. What are ions?
What are ions?
►An ion is an atom or group of atom that
An ion is an atom or group of atom that
has an electric charge because it has
has an electric charge because it has
gained or lost electron.
gained or lost electron.
►[Na]= 1s
[Na]= 1s2
2
2s
2s² 2p
² 2p6
6
3s
3s1
1
► [Na
[Na+
+
] =
] = 1s
1s2
2
2s
2s² 2p
² 2p6
6
►When a sodium atom loses its outermost
When a sodium atom loses its outermost
electron, it becomes positively charged
electron, it becomes positively charged
ion called as sodium ion.
ion called as sodium ion.

3. Cations and anions
Cations and anions
►Ions with a positive charge are called as
Ions with a positive charge are called as
cations. They have more protons than
cations. They have more protons than
electrons.
electrons.

4. ► Negatively charged ions are called as anions.
Negatively charged ions are called as anions.
They have more electrons than protons.
They have more electrons than protons.
► [Cl
[Cl-
-
] = 1s
] = 1s²2s²2p
²2s²2p6
6
3s²3p
3s²3p6
6
=[Ar]
=[Ar]
► [Cl] =
[Cl] = 1s
1s²2s²2p
²2s²2p6
6
3s²3p
3s²3p5
5
► Collection of cations are never found without
Collection of cations are never found without
the formation of similar number of anions. The
the formation of similar number of anions. The
concept of having equal number of positive
concept of having equal number of positive
charges is called electroneutrality.
charges is called electroneutrality.

5. Class Practice
Class Practice
►What will be the electronic configuration
What will be the electronic configuration
of
of
►[Ca] and [Ca
[Ca] and [Ca2+
2+
]
]
Write down the number of protons and
Write down the number of protons and
electrons.
electrons.

6. Transition metals
Transition metals
►Not all simple ions are isoelectronic with
Not all simple ions are isoelectronic with
noble gas atoms. The transition metals
noble gas atoms. The transition metals
do not fit this pattern. Lanthanides and
do not fit this pattern. Lanthanides and
actinides elements form cations, mostly
actinides elements form cations, mostly
with +3 charges, hence they are not
with +3 charges, hence they are not
isoelectronic with noble gases.
isoelectronic with noble gases.

7. Octet rule
Octet rule
►The tendency of atoms of elements to
The tendency of atoms of elements to
gain or lose electrons so that their outer s
gain or lose electrons so that their outer s
and p orbitals are full with eight
and p orbitals are full with eight
electrons.
electrons.
The tendency of atoms to match the
The tendency of atoms to match the
electron configuration of the s and p
electron configuration of the s and p
orbitals of a noble gas is called the octet
orbitals of a noble gas is called the octet
rule.
rule.

8. Binary ionic compound
Binary ionic compound
►An ionic compound composed of simple
An ionic compound composed of simple
cation and simple anion is called a binary
cation and simple anion is called a binary
ionic compound.
ionic compound.
►Common table salt NaCl is composed of
Common table salt NaCl is composed of
equal number of sodium ions, Na
equal number of sodium ions, Na+
+
and
and
chloride ions Cl
chloride ions Cl-
-
.
.

9. Naming Binary Compounds
Naming Binary Compounds
► The name consists of two words: the name of
The name consists of two words: the name of
the cation followed by the name of the anion.
the cation followed by the name of the anion.
► NaCl sodium chloride
NaCl sodium chloride
► Mg
Mg3
3N
N2
2 magnesium nitride
magnesium nitride
► The magnesium ion,Mg
The magnesium ion,Mg2+
2+
has two positive
has two positive
charges, and the nitride ion, N
charges, and the nitride ion, N3-
3-
has three
has three
negative charges. We must combine in such a
negative charges. We must combine in such a
way that there are as many negative charges as
way that there are as many negative charges as
there are positive charges.
there are positive charges.

10. ►Three Mg
Three Mg2+
2+
cations are needed for every
cations are needed for every
two N
two N3-
3-
anions to produce electrically
anions to produce electrically
neutral compounds. Subscripts denote 3
neutral compounds. Subscripts denote 3
magnesium ions and 2 nitride ions.
magnesium ions and 2 nitride ions.

11. Home work
Home work
►Page 164 Section review
Page 164 Section review
►Q1) b and c.
Q1) b and c.
►Q2) a, d, e and h.
Q2) a, d, e and h.
►Q3) e, c and d.
Q3) e, c and d.

12. Ionic Bonding
Ionic Bonding
►Sodium a very reactive Group I metal
Sodium a very reactive Group I metal
combines with chlorine a reactive Group
combines with chlorine a reactive Group
17 non metal ( a poisonous yellowish
17 non metal ( a poisonous yellowish
green gas that consists of molecules with
green gas that consists of molecules with
two chlorine atoms bonded together)
two chlorine atoms bonded together)
react a violent exothermic reaction
react a violent exothermic reaction
occurs. The white residue formed from
occurs. The white residue formed from
two dangerous elements is the salt we
two dangerous elements is the salt we
eat every day.
eat every day.

13. Crystal structure of NaCl
Crystal structure of NaCl

14. ►The coulombic force of attraction of
The coulombic force of attraction of
oppositely charged ions is greater than
oppositely charged ions is greater than
the coulombic force of repulsion from the
the coulombic force of repulsion from the
ions of like charges. Coulombic force is
ions of like charges. Coulombic force is
the attraction or repulsion between two
the attraction or repulsion between two
objects that have electric charges.
objects that have electric charges.

15. Energy aspects of salt
Energy aspects of salt
formation.
formation.
►Ionization energy is the energy that must
Ionization energy is the energy that must
be supplied to remove the outermost
be supplied to remove the outermost
electron from an atom. Atoms always
electron from an atom. Atoms always
resist having their electrons removed so
resist having their electrons removed so
their ionization energies are always
their ionization energies are always
positive.
positive.
►Na
Na(g)
(g) +495 kJ/mol --
+495 kJ/mol --
 Na
Na+
+
(g)
(g) +e
+e-
-
(g)
(g)

16. ►Electron affinity is the energy needed to
Electron affinity is the energy needed to
put an extra electron into a neutral atom.
put an extra electron into a neutral atom.
Most electron affinities are negative
Most electron affinities are negative
indicating that the recipient atom easily
indicating that the recipient atom easily
accepts another electron.
accepts another electron.
►Cl
Cl(g)
(g) +e
+e-
-
(g)
(g) -349 kJ/mol --
-349 kJ/mol --
 Cl
Cl-
-
(g)
(g)
►Adding the above two equations we find
Adding the above two equations we find
that the electron transfer from sodium to
that the electron transfer from sodium to
chlorine atom is an endothermic reaction.
chlorine atom is an endothermic reaction.

17. ► Na
Na(g)
(g) +Cl
+Cl(g)
(g) +146 kJ/mol --
+146 kJ/mol --
 Na
Na+
+
(g)
(g) + Cl
+ Cl-
-
(g)
(g)
► This is very different from what happens in the
This is very different from what happens in the
flask. The formation if ions is only a part of the
flask. The formation if ions is only a part of the
reation.
reation.
► 1. The energy must be added to convert 1 mol of
1. The energy must be added to convert 1 mol of
sodium from a solid to a gas.
sodium from a solid to a gas.
Na
Na(s)
(s) + energy --
+ energy --
 Na
Na(g)
(g)
2. More energy must be added to remove one
2. More energy must be added to remove one
electron from each sodium atom.
electron from each sodium atom.
Na
Na(g)
(g) +energy --
+energy --
 Na
Na+
+
(g)
(g) +e-
+e-

18. ► 3. No energy is needed to convert chlorine into gaseous state
3. No energy is needed to convert chlorine into gaseous state
because it is already a gas. However energy must be added to
because it is already a gas. However energy must be added to
break up
break up ½ mole of Cl
½ mole of Cl2
2 molecules to produce 1 mol of chlorine
molecules to produce 1 mol of chlorine
atoms.
atoms.
½Cl
½Cl2(g)
2(g) + energy ---
+ energy ---
 Cl
Cl(g)
(g)
► 4. Some energy is given off when an electron is added to
4. Some energy is given off when an electron is added to
each chlorine atom to form Cl
each chlorine atom to form Cl-
-
ion. This is an exothermic reaction.
ion. This is an exothermic reaction.
Cl
Cl(g)
(g) + e
+ e-
-
--
--
 Cl
Cl-
-
(g)
(g) + energy
+ energy
► 5. Much more energy is given off when Na
5. Much more energy is given off when Na+
+
and Cl
and Cl-
-
ions come
ions come
together to form ionic crystal of NaCl.
together to form ionic crystal of NaCl.
Na
Na +
+
(g)
(g) + Cl
+ Cl-
-
(g)
(g) --
--
 NaCl
NaCl (s)
(s) +energy.
+energy.

19. Properties Of Binary ionic
Properties Of Binary ionic
compounds
compounds
►A simple cation combined with a simple
A simple cation combined with a simple
anion results in binary compounds.
anion results in binary compounds.
►Since they form strong ionic bonds they
Since they form strong ionic bonds they
have higher melting and boiling points.
have higher melting and boiling points.
►Since they have strong ionic bond these
Since they have strong ionic bond these
solids are not good conductors of electricity.
solids are not good conductors of electricity.
►However in solution they form ions which
However in solution they form ions which
help in conducting electricity.
help in conducting electricity.

20. Polyatomic ions
Polyatomic ions
►An electrically charged group of two or
An electrically charged group of two or
more chemically bonded atoms that
more chemically bonded atoms that
functions as a single ion.
functions as a single ion.

21. Charges of poly atomic ions.
Charges of poly atomic ions.

22. Oxidation numbers
Oxidation numbers
► A number assigned to an atom in a polyatomic
A number assigned to an atom in a polyatomic
ion or molecular compound based on complete
ion or molecular compound based on complete
transfer of electrons.
transfer of electrons.
► Some guide lines:
Some guide lines:
► 1. The oxidation number of any free or combined
1. The oxidation number of any free or combined
element is zero.
element is zero.
► 2. Oxidation number for mono atomic ion is the
2. Oxidation number for mono atomic ion is the
charge on the ion.
charge on the ion.
► 3.The oxidation number on hydrogen is +1 unless
3.The oxidation number on hydrogen is +1 unless
combined with a metal when it has a charge -1.
combined with a metal when it has a charge -1.

23. ► The oxidation number of halogen is -1 since
The oxidation number of halogen is -1 since
more electro negative.
more electro negative.
► Oxygen has an oxidation number -2 except in
Oxygen has an oxidation number -2 except in
peroxides it is -1 and when combined with
peroxides it is -1 and when combined with
fluorine it is +2.
fluorine it is +2.
► In compounds the metals in Group I,II and Al
In compounds the metals in Group I,II and Al
have oxidation numbers +1,+2 and +3.
have oxidation numbers +1,+2 and +3.
► The sum of the oxidation number for all the
The sum of the oxidation number for all the
atoms in a compound is zero.
atoms in a compound is zero.
► The sum of the oxidation number for all
The sum of the oxidation number for all
polyatomic ion is equal to the charge on that
polyatomic ion is equal to the charge on that
ion.
ion.

24. Homework
Homework
►Page 181
Page 181
►# 1-5
# 1-5

25. Silicates and Hydrates
Silicates and Hydrates
Silicates are any compounds containing
Silicates are any compounds containing
silicon, oxygen, one or more metals, and
silicon, oxygen, one or more metals, and
possibly hydrogen
possibly hydrogen

26. ►Ionic compounds like copper sulfate
Ionic compounds like copper sulfate
CuSO
CuSO4
4 with water molecules incorporated
with water molecules incorporated
into their crystal lattices are called
into their crystal lattices are called
hydrates. Some salts form hydrates. E.g
hydrates. Some salts form hydrates. E.g
CuSO
CuSO4
4.5H
.5H2
2O
O

27. ►When a hydrated compound is heated to
When a hydrated compound is heated to
get rid of the water molecule the
get rid of the water molecule the
remaining salt is anhydrous.
remaining salt is anhydrous.

28. Homework
Homework
►Page 184
Page 184
►Q.3 a, c, e, f, i ,j
Q.3 a, c, e, f, i ,j
►Q.4 all
Q.4 all
►Q.5. a, c, d, e, h.
Q.5. a, c, d, e, h.

29. Class work
Class work
►Test prep page 191.
Test prep page 191.