Ionic Bonding

Chapter 20

A. Ionic Bonds

Attraction between 2 oppositely charged ionsIons - charged

atoms caused by

gain or loss of

electronsformed by

transferring e-

from a metal to a nonmetal

A. Ionic Bonds

Cations (metals) first, anions written second (nonmetals or polyatomic ions)

Do NOT share electrons, one gains, and one loses

B. Ionic Compounds

Network of ions, NOT a molecule When melted or dissolved in water,

ionic compounds conduct electricity Ions are free to move, electric current

is moving charges

C. Comparison Chart

IONIC COVALENT

Electrons

MeltingPoint

Soluble in Water

Conduct Electricity

OtherProperties

transferred from metal to nonmetal

high

yes (solution or liquid)

yes

crystal lattice of ions, crystalline solids

shared between nonmetals

low

no

usually not

molecules, odorous liquids & gases

Ch. 20 - Ionic Bonds

Naming Ionic Compounds Oxidation Number

Ionic Names

Ionic Formulas

A. Oxidation Number

The charge on an ion Indicates the # of e- gained/lost to

become stable1+

2+ 3+ 4± 3- 2- 1-

0

For binary ionic compounds (2 elements)

Write the names of both elements, cation first

Change the anion’s ending to –ide

NO PREFIXES!!

NaCl = sodium chloride

CaCl2 = calcium chloride

B. Ionic Names

NaBr

Na2O

AlCl3

sodium bromide

sodium oxide

aluminum chloride

B. Ionic Names

1. Write each ion including the oxidation number Cation is written first Oxidation numbers are written as superscripts

2. Overall charge must equal zero If charges cancel, just write the symbols If not, crisscross the charges to find subscripts

C. Ionic Formulas

C. Ionic Formulas

Calcium chloride Ca2+ Cl1-

charges do not cancel, must criss-cross charges

Rewrite as complete formula without oxidation numbers

CaCl2

21

potassium chloride

magnesium nitride

calcium oxide

K+ Cl KCl

Mg2+ N Mg3N2

Ca2+ O CaO

C. Ionic Formulas

D. Polyatomic Ions

A group of bonded atoms that have gained or lost e-

List on chart – need to know these for Quiz on Tuesday!!!

Parentheses are put around these when naming – (NH4)2SO4 = ammonium sulfate

Naming compounds with PA ions:

For ionic compounds with more than 2 elements

• Write the names of both ions, cation first

Write the full names of polyatomic ions (usually anion) – do not change the names

D. Polyatomic Ions

calcium hydroxide

aluminum chlorate

magnesium carbonate

Ca2+ OH Ca(OH)2

Al3+ ClO3 Al(ClO3)3

Mg2+ CO32 MgCO3

E. Ionic Formulas with PA Ions

1. Write each ion including the oxidation number Cation is written first

2. Overall charge must equal zero If charges cancel, just write the symbols If not, crisscross the charges to find subscripts

3. Use parentheses when more than one polyatomic ion is needed

E. Ionic Formula with PA ions

calcium hydroxide

aluminum chlorate

magnesium carbonate

Ca2+ OH Ca(OH)2

Al3+ ClO3 Al(ClO3)3

Mg2+ CO32 MgCO3

E. Ionic Formulas with PA Ions

F. Ionic Compounds with Transition Metals

For transition metals, valence electrons and oxidation #’s are variableExceptions: Sn (tin), Pb (lead), AgSn (tin), Pb (lead), Ag1+1+, and , and

ZnZn2+2+

Roman numerals indicate the oxidation #

Chromium (III) = Cr3+

Iron (II) = Fe2+

Lead (IV) = Pb4+

Copper (II) bromide

Tin (IV) oxide

Manganese (II) chloride

Cu2+ + Br - CuBr2

Sn4+ + O2- Sn2O4 SnO2

Mn2+ + Cl - MnCl2

G. Ionic Formulas with Transition Metals

H. Naming Ionic Compounds with Transition Metals

Write the ox. # in parentheses using Roman numerals. To determine oxidation #, know that overall charge of compound = 0

Cr2O3

CrO

3 x -2 = -6

2 x ___ = +6-3Chromium (III) oxide

2 x -2 = -4

2 x ___ = +4+2 Chromium (II) oxide

Formula:

Element: # atoms x charge = total charge

H. Naming Ionic Compounds with Transition Metals

Shortcut that sometimes works – criss-cross backwards

CrCl2 Cr Cl2

•chromium (II) chloride

2 1

Cr2(SO4)3

HgO

FeCl3

Chromium (III) sulfate

Mercury (II) oxide

iron(III) chloride

I. Ionic Names with Transition Metals