Transcript Ch 6.3 Ionic Bonding.

Section 6.3
Ionic Bonding and Ionic Compounds
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Warm-Up
How is a chemical formula for
a covalent compound
different from the chemical
formula for an ionic
compound?
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Ionic Compounds
Made up of positive ions
(cations) and negative ions
(anions) that are combined so
that the numbers of positive
and negative charges are
equal.
The chemical formula of an
ionic compound represents the
simplest ratio of the
compound’s combined ions.
Crystals

Most ionic compounds
are crystalline solids a three-dimensional
network of positive and
negative ions mutually
attracted to one another.
Formula Units

fluoride,
Unlike molecular compounds, ionic Calcium
CaF (fluorite)
compounds are not made up of independent
units that can be isolated and examined
Ionic solids exist as repeating units of
positively and negatively charged ions in a 3dimensional structure.
Formula units are the simplest collection of
atoms from which an ionic compound’s
formula can be established and that gives
electrical neutrality
2


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Monatomic Ions
By gaining or losing electrons many main
group elements form ions with noble gas
configurations.
Ions formed from a single atom are called
monatomic ions.
There is a PATTERN for which charge will
form on an atom for the main groups.
+1 +2
SKIP
+4
+3 -4 -3 -2 -1 0
Formulas for Ionic Compounds

The charges must balance to 0, and the
formula must reflect this.
 Ionic compounds do not form by the
combination of isolated ions, but we can use
electron dot notation to see the changes that
take place in ionic bonding.
 Li and F LiF
Mg and F MgF2
Formulas for Ionic Compounds

In your table groups come up with rule(s) for
writing chemical formulas for ionic
compounds.
 Li and F LiF
Al and O Al2O3
 Li and O Li2O
Al and F AlF3
 Mg and F MgF2
 Mg and O MgO
Rule???
Crisscross the charges!
 Write the symbol for each ion, metals
first.
 Write the charge above each.
 If the charges add up to zero, you’re
done.
 If they don’t, play the criss-cross game.
 Example:
Li+ O2- = Li2O

Your Turn

Write the formula for the following:
Li2S
a. Li and S
Al2O3
b. Al and O
KI
c. I and K
d. Mg and F MgF2
AlN
e. N and Al
f. Ca and Br CaBr2
What’s in a name?
Activity Directions:
1. In your table groups, examine the table on
page 2 and come up with at least three
rules for naming ionic compounds based
on the examples given.
2. Answer the making sense question and
practice problems #1-6 and 1-8.
3 Rules?
• Positive ion (metal) always comes first
• Change ending of nonmetal to –ide
• Add Roman numerals to show the charge
on transition metals
Name the following ionic compounds:
1. NaCl
Sodium Chloride
2. K2S
Potassium Sulfide
3. Ca3N2
Calcium Nitride
4. FeS
Iron (II) Sulfide
5. CoF2
Cobalt (II) Fluoride
6. ZnCl2
Zinc (II) Chloride
Actually just Zinc Chloride b/c Zinc only has 1 possible charge
Write the following ionic compounds:
1. Magnesium iodide
MgI2
2. Lithium bromide
LiBr
3. Calcium Phosphide
4. Aluminum Nitride
4. Aluminum Chloride
5. Potassium Oxide
Ca3P2
AlN
AlCl3
K2O
6. Iron (III) Sulfide
Fe2S3
7. Copper (II) Chloride
CuCl2
Check-in:
• Write the symbols for the cation and anion
in the ionic compound PbCl4 and name the
compound.
Pb4+ and Cl1- Lead (IV) Chloride
Homework #1-2
1. Name the following binary ionic
compounds.
a. K3N Potassium nitride
b. CoF2 Cobalt (II) Fluoride
c. PbI2 Lead (II) Iodide
d. SnS2 Tin (IV) Sulfide
e. NiO Nickel (II) Oxide
f. ZnCl2 Zinc (II) Chloride
g. Ag3P Silver (I) Phosphide
2. Write the formulas for the following
names:
a. Magnesium iodide MgI2
b. Lithium bromide LiBr
c. Aluminum chloride AlCl3
d. Calcium phosphide Ca3P2
e. Potassium oxide K2O
f. Iron (III) sulfide Fe2S3
g. Copper (I) Chloride CuCl
h. Gold (III) iodide AuI3
i. Zinc (II) oxide ZnO
Monotomic Ions
 Ions formed from a
single atom. Main
group ions form to
a noble gas
configuration:
Al3+, O2-, etc.
Transition metals can
show many different
charges: Pb2+, Pb4+,
etc.
Ratios
To balance the charge, the ratio of the ions in
a formula unit depends on the charges of the
combined ions.
Example: Names – cation first, anion last.
Calcium fluoride (the -ine of the anion is
dropped and replaced by -ide as a suffix
because the fluorine is now in an ionic
compound).
Ca2+ + 2F- → CaF2

Naming Binary Ionic Compounds



Nomenclature: naming
system.
We will go over the Stock
System of Nomenclature
(Chapter 7, Section 1, pp.
206-210).
You MUST use Table 7-1
p. 205 and Table 7-2 p. 210
to help you in naming ionic
compounds.
Polyatomic Ions

Consist of more than
one atom and the
group is charged:
NH4+, SO42-, etc.
Formation of Ionic Compounds
• Ionic compounts do not form by the
combination of isolated ions, but electron dot
notation can be used to demonstrate the
changes that take place.
Mama Nature Strikes Again

Since nature favors
situations of lowered
potential energy, ions do
this by arranging into an
orderly 3-D arrangement
known as a crystal lattice.
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Structure:

3-D crystals balance + and -charges
ex. Na1+Cl1- = NaCl,
Ca2+ 2F1- = CaF2
 The ions in the crystal are surrounded
by ions of opposite charge.
 Energy is released
when ions form bonds.
Lattice Energy
 This is the
energy released
when one mole
of an ionic
crystalline
compound is
formed from
gaseous ions
(see table 6-3 on
p. 179).
Ionic

vs.
Molecular
bonding:
Very strong, hard and
brittle.






Solids at room T

Higher bp/mp
Conduct heat & electricity 
in molten state.
Many soluble in water.
Strong within molecule;
weak between
molecules.
Mostly gases and
liquids @ room T
(vaporize readily)
Lower bp/mp.
Don’t conduct.
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Polyatomic Ions



Groups of covalently bonded
atoms can have charges.
Ex. PO43−
The phosphate anion is a
covalently bonded molecule
that has gained 3 electrons and
has become an ion. It is able to
bond with another ion such as
Fe2+ to give Fe3(PO4)2 [iron (II)
phosphate].
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Assignment:
Worksheets:
6-3 Review
Chapter 6 Review, pp.
195-198, 11, 19, 35-39,
41, 42, 54, 56, 57, 6365.
Do all assignments from
the book separately.
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