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?
• Nonmetals will do what?
• Once electrons are transferred, the atoms are converted to ions.
lose electron(s)
gain electron(s)
Ions• Positively charged ions are called?
• Negatively charged ions are called?
• Bond to make an ionic compound or salt
cations
anions
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 ionsCr2+ 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 IonsCo2+ 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+ Mercury (II) ion Mercuric ion
Monatomic IonsSn2+ 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
Na1+Cl1-1 1
= NaCl
= MgCl2= AlCl3
Mg2+Cl1-1 2
Al3+ Cl1-1 3
Making Ionic Compounds
NaCl
MgCl2
AlCl3
sodium chloride
magnesium chloridealuminum chloride
Making Ionic Compounds
Na1+ S 2-2 1
= Na2S
= MgO
= Ca3P2
Mg2+O 2-2 2
Ca2+P 3-3 2
Making Ionic Compounds
Na2S
MgO
Ca3P2
sodium sulfide
magnesium oxide
calcium phosphide
Making Ionic Compounds
Pb4+ O 2-2 4
= PbO2
= AgI
= Fe2O3
Ag1+I 1-1 1
Fe3+O 2-2 3
Making Ionic Compounds
PbO2
AgI
Fe2O3iron (III) oxide orferric oxide
silver iodide
Lead (IV) oxide orplumbic oxide
Making Ionic Compounds
Pb4+ (OH)1-1 4
= Pb(OH)4
= MgSO4
= Al2(C2O4)3
Mg2+(SO4)2-2 2
Al3+(C2O4)2-2 3
Making Ionic Compounds
Pb(OH)4
MgSO4
Al2(C2O4)3
lead (IV) hydroxide orplumbic hydroxidemagnesium sulfate
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
CsClCs+ ion
Cl- ion
Now…•PRACTICE•PRACTICE•PRACTICE