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IONIC BONDING
What is an ion?
• An ion: an atom or bonded group of
atoms with a positive or negative charge
Cation: A positively charged ion
Anion: A negatively charged ion
Ionic Compound
• Composed of positive and negative ions that are
combined so that the numbers of positive and
negative charges are equal
• An ionic bond is the electrostatic force that
holds oppositely charged particles together in an
ionic compound.
Properties of Ionic Compounds
• Formed by ionic bonds
• Electrons are either gained or lost
• Have a regular repeating pattern called a crystal
lattice
• Elements are generally far apart from each other
(metals with nonmetals; cations with anions)
• High Melting point and Boiling Point
• Conductors of electricity when mixed with water
• Formation of these is exothermic
• Strong bonds; stronger than covalent bonds
Ionic Bonds continued:
Ionic Bonding - Crystal Lattice
The strong attraction of positive ions and
negative ions in an ionic compound results
in a crystal lattice.
 A crystal lattice is a three
dimensional geometric arrangement of
particles.
 In a crystal lattice, each + ion is
surrounded by - ions and each
– ion is surrounded by + ions.
Ionic crystals vary in shape due to the
sizes and relative numbers of the ions
bonded.
C. Ionic Nomenclature
Common Ion Charges
+1
0
+2
+3 +4/-4 -3 -2 -1
B. Lewis Structures
• Ionic – show transfer of e-
Ionic Bond
an electron is simply transferred to another atom. By doing so, each
atom is able to have a stable valence shell. It is called an ionic bond
because the atoms become ions, a charged atom that has either lost an
electron (positive charge) or has gained an electron (negative charge).
Below is an animation of ionic bonding:
C. Ionic Nomenclature
Ionic Formulas
• Write each ion, cation first. Don’t show
charges in the final formula.
• Overall charge must equal zero.
– If charges cancel, just write symbols.
– If not, use subscripts to balance charges.
C. Ionic Nomenclature
Ionic Formulas
• Use parentheses to show more than one
polyatomic ion.
• Stock System –
– Roman numerals indicate the ion’s charge
• used when the ion has more than one oxidation
state.
C. Ionic Nomenclature
potassium chloride
K+ Cl-

KCl
magnesium nitrate
Mg2+ NO3-

Mg(NO3)2
copper(II) chloride
Cu2+ Cl-

CuCl2
C. Ionic Nomenclature
Ionic Names
• Write the names of both ions, cation first.
• Change ending of monatomic ions to -ide.
• Polyatomic ions have special names.
• Stock System - Use Roman numerals to
show the ion’s charge if more than one is
possible. Overall charge must equal zero.
C. Ionic Nomenclature
NaBr
sodium bromide
Na2CO3
sodium carbonate
FeCl3
iron(III) chloride
C. Ionic Nomenclature
• Consider the following:
– Does it contain a polyatomic ion?
• -ide, 2 elements  no
• -ate, -ite, 3+ elements  yes
– Does it contain a Roman numeral?
• Check the table for metals not in Groups 1 or 2.
Assignment
Provide the ionic compound formula or the
name
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Potassium fluoride
Magnesium phosphide
Aluminum iodide
Nickel II Oxide
Lead IV Oxide
K2CO3
Pb(NO3)2
Ca3N2
Zn(CN)2
AgI