Chapter 8
Ionic Compounds
Formation of Ions
► Which
type of elements are the most stable
(least willing to undergo change)?
► How
many valence electrons do they have?
► What
would you expect of the other
elements to increase their stability?
Octet Rule
► Octet
Rule- atoms gain, lose, or share ein order to acquire a full set of 8
valence e-.
 Ex. sodium
►A
sodium ion is more stable than the neutral
sodium atom because it now has 8 valence e-.
Ions
► Cation
► Anion
► Charge
–written as superscript
Chemical Bonds
► Chemical
bond- an attraction (force)
between atoms that holds them
together
3 Types of Bonds
1. Nonpolar covalent bond- Valence
electrons are shared equally between
bonded atoms
2. Polar covalent bond- Valence electrons
are shared unequally between the bonded
atoms.
3. Ionic bond- Valence electrons are
transferred from one atom to another,
forming ions. These oppositely charged
ions attract holding ionic compounds
together.
Ionic Bonds
► Ionic
compound –
 compound made up of + and - ions that
combine to be neutral
 consists of a metal and nonmetal or a
compound with a polyatomic ion.
Formation of Ionic Cmpds.
► Formation
of ionic compounds-compounds
form to get 8 valence e-
Using electron-dot notation
Ex. Na and Cl to form Na+ and Cl- =
Ex. Al and Cl
to form Al+3 and Cl- =
► Formula
unit-Simplest ratio of the ions
represented in an ionic compound
Ex. MgCl2
Subscripts –number of atoms in a compound
Binary Ionic Compounds
Binary ionic compounds are composed of a
metal cation and a nonmetal anion.
Steps writing Ionic Chemical Formulas:
1. Write symbol and charge of positive ions
first.
2. Write symbol and charge of negative ion
next.
3. Use subscripts if more than one ion is
needed to make the total charge of the
cmpd zero. Reduce ratio if possible.
Write the chemical formulas for the following
compounds:
1.
2.
3.
4.
5.
6.
sodium chloride
aluminum sulfide
manganese (II) nitride
magnesium nitride
zinc oxide
lead (IV) phosphide
Naming Binary Ionic Cmpds.
Name cation, roman numeral, name anion
(if needed)
Using Roman Numerals
Ions with multiple charges:
Transition metals and metals in group 4A of
the periodic table often have more than one
charge. (Exception zinc, silver,
cadmium)
Examples:
1. CaCl2
2. Ba3N2
3. PbO2
4. Na2O
5. MnN
6. GaI2
7. SnCl4
Polyatomic Ions
► Polyatomic
ions-an ion made up of more
than one element
-the ion with more oxygen atoms use the suffix
–ate
-the ion with less oxygen atoms use the suffix
–ite
Polyatomic Ions
Ionic compounds with polyatomic ions:
► Charge applies to entire group of
atoms
► Polyatomic ions act as individual ions
so you can write chemical formulas the
same way as binary compounds.
Examples:
1. Ammonium chloride
2. Aluminum carbonate
3. Calcium phosphate
4. Iron(III) perchlorate
Polyatomic Ions
Naming ionic compounds with polyatomic ions
1. Name the cation first, followed by the
anion. Use roman numerals when
necessary.
2. If the compound contains a polyatomic
ion, simply name the ion.
Examples:
1. CaCO3
3. Al(ClO3)3
2. NH4Cl
4. CoCO3
Properties of Ionic Cmpds.
Properties of Ionic Compounds:
► Crystal
lattice-3-D geometric arrangement
of particles that is formed because of a
strong attraction of positive ions and
negative ions in an ionic compound
► High
melting points and boiling points, and
high degree of hardness-Because the
bond is very strong, it takes a lot of
energy to break apart the bond
Properties of Ionic Cmpds.
► Ionic
compounds are brittle
► Electrolyte-Ionic
compounds dissolved in
liquids are good conductors of electricity
because the ions are free to move
► Energy
changes occur when ionic
compounds form
 A positive ion to a negative ion is always
exothermic.
 Lattice energy-energy needed to separate
the ions of the ionic compound. (Strength
of holding ions).
 The more negative the number, the
stronger the bond.
Naming Binary Acids
Acid-A compound that produces
hydrogen ions in solution (hydrogen in
front).
2 types of acids: binary acids and oxyacids
Anion ending
-ide
-ate
-ic
Acid name
hydro ___ ic acid
____ ic acid
____ ous acid
Naming Acids
Examples:
1. HCl
2. H2CrO4
3. HBr
4. HClO3
5. H3P
6. H2S
7. H2SO4
Formulas for Binary Acids
Examples:
1. Hydrosulfuric acid
2. Nitric acid
3. Hydrofluoric acid
4. perchloric acid
5. Hydronitric acid
6. Sulfurous acid
Metallic Bonding
Metallic bonding-bonding due to
attraction between metal atoms and a
sea of electrons.
Explain these properties with bonding
concept.
► Malleability-metals can be hammered
in sheets.
► Ductility-metals
wires
can be drawn into
► Boiling
points- atoms must be
separated from the group of cations
and electrons
► Good
conductors-movement of mobile
electrons around positive cations
Alloys
Alloys-mixture of elements that has metallic
properties
2 types of alloys
1. Substitutional Alloy- Atoms of the original
metallic solid replaced by other metal atoms of
similar size.
2. Interstitial Alloy -The small holes in a metallic
crystal are filled with smaller atoms