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
electrons in order to acquire a full set
of 8 valence electrons.
 Ex. sodium
►A
sodium ion is more stable than the neutral
sodium atom because it now has 8 valence
electrons.
Ions
► Cation:
A positively charged ion formed
when an atom loses an electron
► Anion-
A negatively charged ion formed
when an atom gains an electron
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 positive and
negative ions that combine to be neutral
 consists of a metal and a nonmetal OR a
metal and a polyatomic ion
Formation of Ionic Cmpds.
► Formation
of ionic compounds-compounds
form to get 8 valence electrons
Using Electron Configurations:
► Ex. Na and Cl to Na+ and Cl- = NaCl
Using electron-dot notation
Ex. Na and Cl
to Na+ and Cl- = NaCl
Ions
► Formula
unit-Simplest ratio of the ions
represented in an ionic compound
Ex. MgCl2
► Oxidation
number (charge) –Equals the
number of electrons transferred from or to an
atom in order to form an ion (the charge of a
monatomic ion)
 Written as superscripts-number to the upper right of symbol
 Positive oxidation number-electrons are transferred from
 Negative oxidation number-electrons are transferred to
Binary Ionic Compounds
Binary ionic compounds are composed of a metal cation and a
nonmetal anion.
Writing Ionic Chemical Formulas:
1. Cation symbol first; followed by the anion symbol
2. Subscripts (numbers to the lower right of a symbol that
represent the number of ions of each element) are used to
get an overall neutral compound.
Write the chemical formulas for the following compounds:
1. sodium chloride
5. manganese (II) nitride
2. aluminum sulfide
6. lead (IV) phosphide
3. magnesium nitride
4. zinc oxide
Binary Ionic Cmpds.
Naming binary ionic compounds:
1. Name the cation first and the anion second
2. Use the element name for the cation
3. For the anion, take the root of the element
name plus the suffix –ide.
Examples:
1. CaCl2
3. Na2O
2. Ba3N2
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. PbO2
3. MnCl3
5. GaI2
2. MnN
4. FeF3
Polyatomic Ions
► Polyatomic
one element
ions-an ion made up of more than
► Oxyanion-polyatomic
ion composed of an
element, usually a nonmetal, bonded to one
or more oxygen atoms. Ex.
-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.
2. If the compound contains a polyatomic
ion, simply name the ion.
Examples:
1. CaCO3
3. Al(ClO3)3
2. NH4Cl
4. CoCO3
1.
2.
3.
4.
5.
6.
7.
nickel (II) phosphide
copper (III) chromate
potassium sulfite
silver nitrate
Fe2(SO4)3
CaI2
PbO
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
Naming binary acids (Hydrogen and one other
element)
1. The prefix hydro- is used to name the
hydrogen part of the compound.
2. Add the root of the second element and the
suffix -ic, and finally the word acid.
Naming Acids
Examples:
1. HCl
4. H2S
2. HBr
3. H3P
Formulas for Binary Acids
Examples:
1. Hydrosulfuric acid
2. Hydrofluoric acid
3. Hydronitric acid
Oxyacids
Naming oxyacids (An acid that contains H
and an oxyanion)
1. Identify anion
2. Use a form of the anion + a suffix + the
word acid.
3. If the anion ends in:
 -ate, replace it with the suffix –ic
 -ite, replace it with the suffix –ous
Oxyacids
Examples:
1. H2SO4
3. HClO3
Examples:
1. perchloric acid
3. Chromic acid
2. H2SO3
2. nitric acid
4. hydronitric 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 can be drawn into wires
►
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