IONIC
COMPOUNDS
STABILITY
• Relates to nobility
• Every element’s dream
• They’ll do what they can to look
like a noble gas…pseudo-noble gas
configuration
• Duet Rule
• Octet Rule
• Potential Energy
Bond Energy
• The energy required to break a bond
• The energy is absorbed when the bond
is broken, thus…released when formed
• Stronger bonds are more stable
– Require more energy to break them
– i.e. ionic bonds
• Weaker bonds are less stable
– Require less energy to break them
– i.e. molecular or covalent bonds
Achieving Stability
• Ionic bonds made by transferring
electrons
• Metals will do what?
lose electron(s)
• Nonmetals will do what?
gain electron(s)
• Once electrons are transferred, the
atoms are converted to ions.
Ions
• Positively charged ions are called?
cations
• Negatively charged ions are called?
anions
• Bond to make an ionic compound or
salt
Salts
• Made of metals and nonmetals or
polyatomic ions
• Solid
– Ordered arrangement called crystal
lattice
• Brittle
• High melting point
• Electrical conductors in aqueous and
molten phases
More About Ions
• Written as a symbol with superscript to
the right indicating the charge
• Charge is written as a number followed
by a + or – sign
• Monatomic ions—”one-atomed” ions
• Polyatomic ions—”many-atomed” ions
Monatomic Ions
• Use periodic table to determine
charges of representative elements
• Group 1…1+…element name + ion
• Group 2…2+…element name + ion
• Group 13…3+…element name + ion
• Group 14…skip
• Group 15…3-…ide ending + ion
• Group 16…2-…ide ending + ion
• Group 17…1-…ide ending + ion
Monatomic Ions
• For the transition metals, you must
memorize the possible charges of the
common ions
Cr2+
Chromium (II) ion
Chromous ion
Cr3+
Chromium (III) ion
Chromic ion
Mn2+
Manganese (II) ion
Manganous ion
Mn3+
Manganese (III) ion
Manganic ion
Fe2+
Iron (II) ion
Ferrous ion
Fe3+
Iron (III) ion
Ferric ion
Monatomic Ions
Co2+
Cobalt (II) ion
Cobaltous ion
Co3+
Cobalt (III) ion
Cobaltic ion
Ni2+
Nickel (II) ion
Nickelous ion
Ni3+
Nickel (III) ion
Nickelic ion
Cu1+
Copper (I) ion
Cuprous ion
Cu2+
Copper (II) ion
Cupric ion
Hg22+ Mercury (I) ion
Mercurous ion
Hg2+
Mercuric ion
Mercury (II) ion
Monatomic Ions
Sn2+
Tin (II) ion
Stannous ion
Sn4+
Tin (IV) ion
Stannic ion
Pb2+
Lead (II) ion
Plumbous ion
Pb4+
Lead (IV) ion
Plumbic ion
Ag1+
Silver ion
Zn2+
Zinc ion
Cd2+
Cadmium ion
Polyatomic Ions
• Refer to handout
• Know the formula (that means
elements, subscripts, and charge) of
each listed
Making Ionic
Compounds
• A cation and an anion will bond in
order to bring the charge of the
compound to zero.
• A “criss-cross” method is used to
determine the number of each ion
necessary to balance the charges
• Always reduce subscripts.
Making Ionic
Compounds
1+
1Na1 Cl1
= NaCl
2+
1Mg Cl
= MgCl2
3+
Al
= AlCl3
1
1
2
1Cl
3
Making Ionic
Compounds
NaCl
sodium chloride
MgCl2
magnesium chloride
AlCl3
aluminum chloride
1+
Na
2
Making Ionic
Compounds
2= Na2S
S1
2+
2Mg O
= MgO
2+
3Ca P
= Ca3P2
2
3
2
2
Making Ionic
Compounds
Na2S
sodium sulfide
MgO
magnesium oxide
Ca3P2
calcium phosphide
Making Ionic
Compounds
2= PbO2
O4
4+
Pb
2
1+
Ag
I
3+
Fe
O3
1
2
11
2-
= AgI
= Fe2O3
Making Ionic
Compounds
PbO2
AgI
Lead (IV) oxide or
plumbic oxide
silver iodide
Fe2O3
iron (III) oxide or
ferric oxide
Making Ionic
Compounds
4+
1Pb1 (OH)4 = Pb(OH)4
2+
Mg (SO
2
3+
Al (C
2
2) =
4 2
O
2 4
2)
3
MgSO4
= Al2(C2O4)3
Making Ionic
Compounds
lead
(IV)
hydroxide
or
Pb(OH)4
plumbic hydroxide
MgSO4
magnesium sulfate
Al2(C2O4)3
aluminum oxalate
Crystal Lattice
• 3-dimensional arrangement of atoms or
ions in a solid
• Simplest part is called a unit cell
• There are six types of crystal systems
– We will focus on the cubic unit cell
Cubic Unit Cells
• Three types:
– Simple
– Body-centered
– Face-centered
Simple Cubic Unit
Cell
P
Face-centered Cubic
Unit Cell
NaCl
Cl- ions
Na+ ions
Body-centered Cubic
Unit Cell
CsCl
Cs+ ion
Cl- ion
Now…
•PRACTICE
•PRACTICE
•PRACTICE