in a documented essay of XXXXXXXXXXwords please address the following topics. 1) what is the difference between an ionic and a covalent bond? how is each formed? 2) Explain why ionic compounds...

This type of bond is established by transfer of an electron from one atom to another
1) This type of bond is established by transfer of an electron from one atom to another. Let us consider a general case when an atom A has one electron in the valence shell and another atom B has seven electrons. A has one electrons in excess and B has one electron short than the stable octet. Therefore, A transfers an electron to B and in this transaction both the atoms acquire a stable electron-octet. The resulting positive ion (cation) and negative ion (anion) are held together by electrostatic attraction.
A
x
+
B
A
+
+
B
o
r
A
+
+
(
1

V
A
L
E
N
C
E

E
L
E
C
T
R
O
N
)
B
(
7

V
A
L
E
N
C
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C
T
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C
A
T
I
O
N
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The electrostatic attraction between the cation (+) and anion
(
)
-
produced by electron transfer constitutes an Ionic or Electrovalent Bond.
The compounds containing such a bond are referred to as Ionic or Electrovalent Compounds.
Conditions for Formation of Ionic Bond
The condition favorable for the formation of an ionic bond are
(1) Number of valence electrons.
(2) Net lowering of Energy.
(3) Electro negativity difference of A and B
Some Examples of Ionic Compounds:-
Sodium Chloride,
NaCl
21
2
Magnesiumchloride, MgCl
+-
Calcium oxide,
22
CaO
+-
Aluminum Oxide,
32
23
AlO
--
Characteristic of Ionic Compounds:-
The ionic compounds are made of
(
)
+
and
(
)
-
ions held by electrostatic forces in a crystal lattice each ion is surrounded by the opposite ions in alternate positions in a definite order in all direction. This explains the common properties of ionic compounds.
(1) Solids at room temperature:-
On account of strong electrostatic forces between the opposite ions, these ions are locked in their allotted positions in the crystal lattice. Since they lack the freedom of movement characteristic of the liquid state, they are solids at room temperature.
(2) High Melting Points:-
Ionic compounds have high melting points (or boiling points). Since the
(
)
+
and
(
)
-
ions are tightly held in their positions in the lattice, only at high temperature do the ions acquire sufficient kinetic energy to overcome their attractive forces and attain the freedom of movement as in a liquid.
Thus ionic compounds need heating to high temperature before melting.
(3) Hard and brittle:-
The crystal of ionic substances are hard and brittle. Their hardness is due to the strong electrostatic forces which hold each ion in its allotted position.
+
+
+
+
+
+
+
+
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(
a
)
(
b
)
(a) Two layers of
(
)
+
and
(
)
-
ions in a crystal
(b) when force is applied to one layer it slips over the other so that similar ions come above one another and electrical repulsions between them cause cleavage of the crystal.
These crystals are made of layers (+) and
(
)
-
ions in alternate position so that the opposite ions in the various parallel layers lie over each other. When external force is applied to a layer of ions with respect to the next, even a slight shift brings the like ions in front of each other. The (+) and
(
)
-
ions in the two layers thus repel each other and fall apart. The crystal cleaves here.
(4) Conductors OF electricity:-
Solid ionic compound are poor conductors of electricity because the ions are fixed rigidly in their positions. In the molten state and in water solutions, ions are rendered free to move about. Thus molten ionic...