Section 7.2
Ionic Bonds
And
Ionic Compounds
Formation of an Ionic Bond
Compound
A chemical combination of two or more
different elements
Binary compounds when there are exactly
two different elements
Formation
P. 210 shows chemical reactions that form
ionic bonds and release energy
a. Sodium and chlorine gas produce a
white crystalline solid
Na + Cl  Na+ + Cl- + energy
This is called a chemical equation.
What Happened?
Sodium transferred one valence electron to
chlorine.
+
This is the electron-dot structures
[Na]+ + [Cl]- + energy
Types of Ionic Compounds
Electrostatic force holds the charged atoms
together is the ionic bond.
Metal and non-metal ionic bond are called
oxides.
Most other ionic compounds are called salts.
Names
Sodium + Chlorine forms sodium chloride
Sodium is a metal
Chlorine is a non-metal
Change chlorine to chloride in the name of
the compound
p. 210 b
• Ribbon of magnesium metal burns in air, it
forms the ionic compound magnesium
oxide.
• Magnesium is a metal
• Oxygen is a non-metal
Notice the name, oxygen became oxide.
Is this a binary ionic compound?
Questions
Explain how an ionic compound forms from
these elements
7. sodium and nitrogen
8. lithium and oxygen
9. strontium and flourine
10. aluminum and sulfur
Challenge Question
11. Explain how elements in group 1 and
group 15 combine to form an ionic
compound.
Properties of Ionic Compounds
Physical structure
• Ratio of positive and negative ions
• Ions are packed into repeating pattern
• Balance the forces of attraction and
repulsion between ions
* No single unit of Na and Cl exists, there
are many Na+ and Cl- ions in a 1 to 1 ratio.
Question
What determines the ratio?
Common Ionic Compounds
• Carpet: calcium carbonate
• Ceramics/glass: calcium carbonate, lithium
borate, magnesium silicate, sodium carbonate
• Glossy Paper: aluminum silicate, calcium
carbonate, sodium sulfate, calcium oxide,
sodium carbonate, titanium(IV) oxide
• Toothpaste: calcium carbonate, sodium
carbonate, sodium-hydrogen carbonate, sodium
fluoride
Crystal Lattice
Three dimensional geometric arrangement
of particles
Each positive ion is surrounded by negative
ions and each negative ion is surrounded
by positive ions
The number of ions and the ratio determine
the size and shape
Examples
Minerals
More than 1/3 of all known minerals are
silicates
Halides
Borates
Carbonates
What elements do you think are in these?
Physical Properties
• Melting point
• Boiling point
• Hardness
Depends on how strong the
ionic attraction is
Ionic crystals are hard, rigid,
brittle solids, hard to
break apart – high
melting and boiling points
• Conduct electricity
Solids: ions are locked into
place, cannot conduct
electricity
Melt or dissolve solids into
solutions
Electrolytes are solutions
that conduct electricity
and important to humans
Energy
Endothermic
Exothermic
Energy is absorbed
Energy is released
Formation of ionic
compounds
Forms more stable
system so lower
energy state, release
energy
Math / Graph
Make a scatterplot of Interionic Distance and
Lattice Energy
(kJ/mol)
Title_______________
(μm)
Lattice Energy and Interionic Distance
Ionic Radius: the sum
of the radii of each ion
Li+: 76 μm
F-: 133 μm
Cl-: 181 μm
I-: 220 μm
Find
LiF, LiCl, LiI
Lattice Energy
LiF: -1032 kJ/mol
LiCl: -852 kJ/mol
LiI: -761 kJ/mol
Plot each ionic
compound
Use a different color for
each point and label
Relationship
Use your graph to describe the relationship
between the interionic distance and lattice
energy.
Fill in the blanks:
As interionic distance ________, lattice
energy ___________.
Lattice Energy
• Energy required to separate 1 mol of the
ions in an ionic compound
• The greater the lattice energy, the stronger
the force of attraction ( harder to separate)
Predict
Use your graph to estimate the lattice
energy for LiBr.
The ionic radius of Br- is 196 μm.
Patterns in Lattice Enery
Make a line graph of compound versus
lattice energy (kJ/mol)
Make each set of compounds
a different color, 4 colors
Li set – blue
Na set – red
K set – green
Rb set - orange
Compound Lattice Energy
LiF
LiCl
LiBr
LiI
NaF
NaCl
NaBr
NaI
-1032
-852
-815
-761
-926
-786
-752
-702
KF
KCl
KBr
KI
-813
-717
-689
-649
Make each set of
compounds a different
color
Li set – blue
Na set – red
K set – green
Write a few
sentences to
describe any
pattern you see.
Prediction
• Predict the shape of the graph of the
lattice energies of
• RbF, RbCl, RbBr, RbI
Add to Graph in Orange
• Add the Rb___ compounds to your graph
in orange to verify your prediction.
• RbF 774
Summary
• Ionic compounds contain ionic bonds
formed by the attraction of oppositely
charged ions.
• Ions in a ionic compound are arranged in
repeating patterns known as a crystal
lattice.
• Ionic compounds properties are related to
ionic bond strength.
• Ionic compounds are electrolytes; they
conduct an electric current in the liquid
phase and in aqueous solution.
• Lattice energy is the energy needed to
remove 1 mol of ions from its lattice.
Questions
12. Explain how an ionic compound made up
of charged particles can be neutral?
13. Describe the energy change associated
with ionic bond formation, and relate it to
stabillity.
14. Identify three physical properties of ionic
compounds that are associated with ionic
bonds, and related them to bond
strength.
15. Explain how ions form bonds, and
describe the structure of the resulting
compound.
16. Relate lattice energy to bond strength.
17. Use electron configurations, orbital
notations and electron dot structures to
represent the formation of an ionic
compound from the mental strontium and
the non-metal chlorine.
Question
Using the elements aluminum and oxygen,
determine the formula for the ionic
compound.
Extension: Use Fe2+ and Fe3+ to combine
with O2Determine the formula for the ionic
compounds.
Each Student
List a metal and a non-metal
Exchange papers and determine the ionic
compound formed between them.
Exit Ticket
• Determine the ionic compound formed
from Mg and Cl and explain how it was
formed.
• Include its ratio