Learning Objectives:
 Octet Rule & Predicting ionic Charges
 Ionic Bonds
 Formation of cations by metals
 Formation of anions by nonmetals
 Metals capable of forming multiple charges
 Formation of electronically neutral ionic compounds
 Polyatomic ions
 Naming Ionic Compounds
 Properties of Ionic Compounds
 High Melting & Boiling Points
 Conductive aqueous solutions
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Bonding Definition
• Bonding is the joining of two atoms in a stable arrangement.
• Elements will gain , lose , or share electrons to reach the electron configuration of the noble gas closest to them in the periodic table.
• There are two different kinds of bonding:
1.
Ionic bonds result from the transfer of electrons from one element to another.
2.
Covalent bonds result from the sharing of electrons between two atoms.
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Bonding Definition
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Bonding Ionic Bonds vs Covalent Bonds
Ionic bonds form between:
• A metal (left side periodic table)
• A nonmetal (right side periodic table)
Covalent bonds are formed when two nonmetals combine, or when a metalloid bonds to a nonmetal.
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Ions Cations
Cations are positively charged ions. A cation has fewer electrons (e
−
) than protons.
the sodium atom
Smith. General Organic & Biolocial Chemistry 2nd Ed.
the sodium ion
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Ions Anions
Anions are negatively charged ions. An anion has more e − than protons.
the chlorine atom
Smith. General Organic & Biolocial Chemistry 2nd Ed.
the chlorine ion
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Ions The Octet Rule
The octet rule : a main group element is especially stable when it possesses an octet of e
− in its outer shell.
8
−
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Smith. General Organic & Biolocial Chemistry 2nd Ed.

Ions Charge as Determined by Periodic Group
group 1A: M
1 valence e
−
M + + e
− group 2A: M
2 valence e −
M 2+ + 2e
− group 3A: M
3 valence e −
M 3+ + 3e −
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Ions Charge as Determined by Periodic Group
group 6A: X
6 valence e −
+ 2e −
X 2
− charge = 8 – 6 = 2 group 7A: X
7 valence e
−
+ e −
X
− charge = 8 – 7 = 1
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Smith. General Organic & Biolocial Chemistry 2nd Ed.

Ions Main Group Ions
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Ions Metals with Variable Charges
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Ions Biologically Relevant Ions http://www.drcruzan.com/Chemistry_PeriodicTable.html
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Ionic
Compounds
Definition & Solid Structure
• The sum of the charges in an ionic compound must be zero overall .
• Ions will arrange to maximize anion-cation attractions and minimize anion-anion and cation-cation repulsions
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Ionic
Compounds
Charge Balance
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Ionic
Compounds
Formula for Ionic Compounds
HOW TO Write a Formula for an Ionic Compound
Step [1]
Identify which element is the cation and which is the anion.
Step [2]
Determine how many of each ion type is needed for an overall charge of zero .
 When the cation and anion have different charges, use the ion charges to determine the number of ions of each needed.
Step [3]
To write the formula, place the cation first and then the anion , and omit charges.
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Ionic
Compounds
Criss-Cross Rule
“ Criss-cross ” rule
 Make magnitude of charge on one ion into subscript for other
 When doing this, make sure that subscripts are reduced to lowest whole number .
Al 3+ O 2 –
Al
2
O
3
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Naming Main Group Cations
Main group cations are named for the element from which they are formed.
Na + sodium
K + Ca 2+ potassium calcium
Mg 2+ magnesium
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Naming Multiple Charge Cations
Systematic name : Follow the name of the cation by a Roman numeral in parentheses to indicate its charge.
Fe iron(
2+
II )
Fe 3+ iron( III )
Common name : Use suffix “ ous ” for the cation with a smaller charge and suffix “ ic ” for the cation with a higher charge.
Fe 2+ ferr ous
Fe ferr
3+ ic
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Naming Anions
Anions are named by replacing the ending of the element name by the suffix “ ide .
”
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Naming Ionic Compounds
•Name the cation and then the anion .
•Do not specify the charge on the ion.
•Do not specify how many ions of each type are needed to balance charge.
Na + sodium
+ F
− fluoride
Mg 2+ magnesium
+ Cl
− chloride
NaF sodium fluoride
MgCl
2 magnesium chloride
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Smith. General Organic & Biolocial Chemistry 2nd Ed.

Naming Ionic Compounds
HOW TO Name an Ionic Compound
Step [1] Determine the charge on the cation .
Step [2]
Step [3]
Name the cation and the anion
 If the cation could be multiple charges indicate the charge with roman numerals or with a
–ous / -ic suffix.
Write the name of the cation first then the name of the anion
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Naming Ionic Compounds
HOW TO Derive the Formula from the Name of an Ionic Compound
Step [1] Identify the cation and the anion .
Step [2] Determine the charge on the cation and anion .
Step [3]
Balance the charges.
Step [4]
Write the formula with the cation first and use subscripts to communicate charge balance.
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Properties Physical Properties of Ionic Compounds
•Ionic compounds are crystalline solids with very high melting and boiling points .
•When ionic compounds dissolve in water, they separate into cations and anions , increasing the conductivity of the solution.
+ 
NaCl water solution

Polyatomic
Ions
Definition
A polyatomic ion is a cation or anion that contains more than one atom.
The multiple atoms are held together with covalent bonds
The molecule has an overall charge associated with it.
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Polyatomic
Ions
Writing Formula
When a cation and anion of equal charge combine, only one of each ion is needed.
Na + + NO
2
− NaNO
2 zero overall charge
Ba 2+ + SO
4
2
−
BaSO
4 zero overall charge
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Polyatomic
Ions
Writing Formula
When a cation and anion of unequal charge combine, use the ionic charges to determine the relative number of each ion that is needed.
Mg 2+
+2 charge means
2 OH
− anions are needed.
+ OH −
−1 charge means
1 Mg 2+ anion is needed.
Mg(OH)
2 zero overall charge
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Polyatomic
Ions
Naming Ionic Compounds
The same rules are followed for naming standard ionic compounds:
•Name the cation and then the anion .
•Do not specify the charge on the ions.
•Do not specify how many ions of each type are needed to balance charge.
•Use –ite suffix if 1 or less Oxygen atoms in anion
•Use –ate suffix if more Oxygen atoms in anion
•Use bi- prefix or write hydrogen if H part of anion
NaHCO
Smith. General Organic & Biolocial Chemistry 2nd Ed.
3 sodium bicarbonate
Al
2
(SO
4
)
3 aluminum sulfate
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