This document describes the formation and properties of ionic compounds. Ionic bonds form when oppositely charged ions attract each other to form electrically neutral compounds. Ionic compounds have high melting and boiling points because the ionic bonds between ions require a large amount of energy to overcome. The ions are tightly packed in a crystal lattice structure. Physical properties like conductivity depend on whether the ions are free to move or locked in place. Smaller or more highly charged ions result in stronger ionic bonds and higher lattice energies.

2. Objectives
Describing the formation of ionic bond
Explaining: compound formation and
charge

3. True or False
Table salt (sodium chloride ) conducts
electricity .

4. Ionic Bonds And Ionic Compounds
 Oppositely charged ions attract each other,
forming electrically neutral ionic compounds
 Formation of an Ionic Bond
 Ionic bond : The electrostatic force that holds
oppositely charged particles together in an ionic
compound
 Compounds that contain ionic bonds are Ionic
compounds
 If ionic bonds occur between metals and the (oxygen) , oxides
form. Most other ionic compounds are called salts.

5. Binary ionic compounds
 Ionic Compounds that contain only two different
elements
 For Example : NaCl contains two different elements,
which are sodium and chlorine.

6. Compound formation and charge
Example (calcium fluoride )
 Calcium needs to lose two electrons to attain the stable
configuration of argon.
 Fluorine must gain one electron to attain the stable
configuration of neon
(1()2( + )+2()1–= )
0

7. 7- sodium loses one electron to form 1+ ion and nitrogen needs
to gain 3 electrons forming 3- ion
The ions attract forming Na3N

8. Summarize the charges on each ion
in the following ionic compounds
MgO , NaF , SrCl2
Mg 2+ , O2- , Na + , F - ,Sr 2+ , Cl -

9. Physical properties of ionic compounds
 Melting point, boiling point, and hardness are physical
properties of matter that depend on how strongly the
particles that make up the matter are attracted to one
another
 the ability of a material to conduct electricity depends on
the availability of freely moving charged particles.
 In the solid state, the ions in an ionic compound are locked
into fixed positions by strong attractive forces. As a result,
ionic solids do not conduct electricity.
 but when an ionic solid melts to become a liquid or is
dissolved in solution. The ions are now free to move and
conduct an electric current.

10. Physical properties
 Electrolyte :An ionic compound whose aqueous
solution conducts the electricity
 Ionic crystals have high melting points and high
boiling points , Why?
 Because ionic bonds are relatively strong, ionic crystals
require a large amount of energy to be broken apart

11. What makes the crystal cracks ?
the crystal cracks or breaks apart, as shown in
Figure 9. The crystal breaks apart because the
applied force repositions the like-charged ions
next to each other; the resulting repulsive force
breaks apart the crystal.

12. Energy and the Ionic Bond
Exothermic
Endothermic
During every chemical reaction, energy is
either absorbed or released.
If energy is absorbed during a chemical reaction, the
reaction is endothermic. If energy is released, it is
exothermic
The formation of ionic compounds from positive ions
and negative ions is always Exothermic

13. Properties of Ionic Compounds
 the ionic bonds produce unique physical structures,
unlike those of other compounds
 A crystal lattice is a three-dimensional geometric
arrangement of particles
 lattice energy :the energy required to separate 1 mol of
the ions of an ionic compound
 In a crystal lattice, each positive ion is surrounded by
negative ions, and each negative ion is surrounded by
positive ions.

14. crystal lattice
is a three-dimensional geometric arrangement of
particles In a crystal lattice, each positive ion is
surrounded by negative
 The greater the lattice energy, the stronger the force of
attraction.
 Lattice energy is related to the size of the ions
bonded.
Because the electrostatic force of attraction between
opposite charges increases as the distance between
the charges decreases

15. 1- Smaller ions produce stronger interionic
attractions and greater lattice energies.
• For example :
• The lattice energy of a lithium compound is
greater than that of a potassium compound
containing the same anion because the lithium
ion is smaller than the potassium ion.
2- The value of lattice energy is also affected by the
charge of the ion.
• The ionic bond formed from the attraction of
ions with larger positive or negative charges
generally has a greater lattice energy.
Size and charge & lattice energy
So : MgO is four times greater than NaF