ionic compounds. stability relates to nobility every element’s dream they’ll do what they can to...

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