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