Chapter 7
“Ionic and Metallic
Bonding”
7.1 - Ions
Valence Electrons are…?


Valence electrons –
The s and p electrons
in the outer energy level
– the highest occupied energy level
Core electrons – electrons
in the energy levels below.
Keeping Track of Electrons

Atoms in the same column...
1) Have the same outer electron
configuration.
2) Have the same valence electrons.
1) Electron configuration of Group 1A?
– 𝒔𝟏
2) Number of valence electrons in Group 1A?
–
1


The number of valence electrons are
easily determined. It is the
group number for a
representative element
Group 2A: Be, Mg, Ca, etc.
– have 2 valence electrons
Electron Dot diagrams are…





A way of showing
valence electrons.
How to write them?
Write the symbol –
represents the nucleus and
inner (core) electrons
Put one dot for each
valence electron
(8 maximum)
They don’t pair up
until they have to (Hund’s rule)
X
The Electron Dot diagram for
Nitrogen
Nitrogen has 5 valence
electrons to show.
 First we write the symbol.
Then add 1 electron at a
time to each side.
Now they are forced to pair up.
We have now written the electron dot
diagram for Nitrogen.

N
Practice with e- dot structure

Li

N

Be

O

B

F

C

Ne
The Octet Rule


The Octet Rule:
in forming compounds, atoms tend to achieve a
noble gas configuration;
8 in the outer level
Each noble gas (except He, which has 2) has
8 electrons in the outer level
Formation of Cations
Metals lose electrons
to attain a noble gas configuration.
– Where are metals located? Left
 Make positive ions (cations)

Formation of Cations
If we look at the electron configuration, it
makes sense to lose electrons:
 Na 1s22s22p63s1 1 valence electron
 Na1+ 1s22s22p6
This is a noble gas configuration with 8
electrons in the outer level.

Electron Dots For Cations

Metals will have few valence
electrons (usually 3 or less);
calcium has only 2 valence electrons
Ca
Electron Dots For Cations

Metals will lose all
valence electrons
Ca
Electron Dots For Cations
Metals will lose the valence electrons
 Form positive ions

2+
Ca
This is the
“calcium ion”.
NO DOTS are now shown for the cation.
Practice

# of valence electron

Cation formed

Na = 1

𝑁𝑎+1

Mg = 2

𝑀𝑔+2

Al = 3

𝐴𝑙 +3
The transition
metals get
funky…
Electron Dots For Cations
Let’s do Scandium, #21
 The electron configuration is:
1s22s22p63s23p64s23d1
 Thus, it can lose 2e- (making it 2+), or lose 3e(making 3+)
Sc = Sc2+
Sc = Sc3+

Scandium (II) ion
Scandium (III) ion
Electron Dots For Cations




Let’s do Silver, element #47
Predicted configuration is:
1s22s22p63s23p64s23d104p65s24d9
Actual configuration is:
1s22s22p63s23p64s23d104p65s14d10
Ag = Ag1+
(can’t lose any more, charges of 3+ or greater
are uncommon)
Electron Dots For Cations
 Silver did the best job it
could, but it did not achieve a
true Noble Gas configuration
 Instead, it is called a
“pseudo-noble
gas configuration”
Electron Configurations: Anions





Nonmetals gain
electrons to attain
noble gas configuration.
They make negative ions (anions)
S = 1s22s22p63s23p4 = 6 valence electrons
S2- = 1s22s22p63s23p6 = noble gas
configuration.
Halide ions - ions from
chlorine or other halogens that gain electrons
Electron Dots For Anions
Nonmetals will have many
valence electrons (usually 5 or more)
 They will gain electrons to fill outer shell.

P
3(This is called the “phosphide
ion”, and shows dots)
Stable Electron Configurations




All atoms react to try and achieve a noble
gas configuration.
Noble gases have 2 s and 6 p electrons.
8 valence electrons = stable
This is the octet rule
(8 in the outer level is particularly stable).
Ar
Review
How many valence electrons do the following
elements have?
Ga = 3
P=5
 Cl = 7
S=6
 Mg = 2

K=1
 Li = 1
 He = 2
F=7
 Ne = 8

Review
Draw the electron dot structure of the following
elements.

Ga

K

P

He

S

F

Mg

Ne
Review
What ions will the following elements form?

𝐺𝑎+3

𝑀𝑔+2

𝑃−3

𝐹 −1

𝐾 +1

𝑆 −2
7.2 - Ionic Bonds
and Ionic
Compounds
Ionic Bonding
Anions and cations are held together by
opposite charges (+ and -)
 Ionic compounds are called salts.
 Formula unit –
Simplest ratio of
elements in an ionic compound.

Practice with Formula Unit
What is the formula unit for the following
compounds?
 Formula Unit
 NaCl
1:1
 𝐻2 𝑂
2:1
 𝐶𝑎𝐶𝑂3
1:1:3

Ionic Bonds


Formed through the
transfer of electrons
(lose and gain)
Electrons are transferred to achieve
noble gas configuration.
Ionic Compounds
1) Also called SALTS
2) Made from a
CATION and ANION
• A metal and a nonmetal)
Ionic Bonding
Na Cl
• The metal loses
its one electron from the outer level.
• The nonmetal gains
one more to fill its outer level, and will
accept the one electron that the metal is
going to lose.
Ionic Bonding
+
Na
Cl
-
Note: Remember that NO DOTS
are now shown for the cation!
Ionic Bonding
Example- combine Ca and P:
Ca

P
All electrons must be
accounted for,
and each atom will have a noble gas
configuration (which is stable).
Ionic Bonding
Ca
P
Ionic Bonding
2+
Ca
P
Ionic Bonding
2+
Ca
Ca
P
Ionic Bonding
2+
Ca
Ca
P
3-
Ionic Bonding
2+
Ca
P
Ca
P
3-
Ionic Bonding
2+
Ca
P
2+
Ca
P
3-
Ionic Bonding
Ca
2+
Ca
P
2+
Ca
P
3-
Ionic Bonding
Ca
2+
Ca
P
2+
Ca
P
3-
Ionic Bonding
2+
Ca
2+
Ca
2+
Ca
P
P
33-
Ionic Bonding
= Ca3P2
• Chemical formulashows the kinds and
numbers of atoms
in the smallest
representative particle of the substance.
Balancing Ionic formulas
Crisscross method
 The numerical value of the
charge of each ion is
crossed over and becomes the
subscript for the other ion.

Practice
What will the chemical formula look like?

Elements

Ca+2
F-
𝐶𝑎𝐹2

Al+3
O-2
𝐴𝑙2 𝑂3

Ca+2
O-2
𝐶𝑎𝑂

Formula
Properties of Ionic Compounds
1. Crystalline solids –
regular repeating arrangement of ions
 Strongly bonded together.
 Structure is rigid.
2. High melting points
 Coordination numbernumber of ions of opposite charge
surrounding it
- Page 198
Coordination Numbers:
NaCl
Both the sodium
and chlorine have 6
CsCl
Both the cesium
and chlorine have 8
TiO2
Each titanium has
6, and each oxygen
has 3
Do they Conduct?
Conducting electricity means
allowing charges to move.
 In a solid, the ions are locked in place.
 Ionic solids are insulators.
 When melted, the ions can move.
3. Melted ionic compounds conduct.
– NaCl: must get to about 800 ºC.
– Dissolved in water,
they also conduct
(free to move in aqueous solutions)

- Page 198
The ions are free to move when they are
molten (or in aqueous solution), and thus they
are able to conduct the electric current.
Review
What is the formula unit for the following
compounds?

KCl
1:1

𝐹𝑒2 𝑂3
2:3

𝐹𝑒𝑆2
1:2

𝐵𝑎𝑆𝑂4
1:1:4

HgS
1:1

𝑁𝑎2 𝑂
2:1
Practice
What will the chemical formula look like?






Elements
Na+
ClMg+2
FCa+2
N-3
Al+3
N-3
K+
S-2

Formula
 𝑁𝑎𝐶𝑙
𝑀𝑔𝐹2
 𝐶𝑎3 𝑁2
 𝐴𝑙𝑁
 𝐾2 𝑆
7.3 –
Bonding in
Metals
Metallic Bonds are…



How do we get sheets of Aluminum (or any
metal)?
Metals hold on to their valence electrons
very weakly.
Think of them as positive ions (cations)
floating in a sea of electrons
Sea of Electrons
 Electrons
are free to move
through the solid.
 Metals conduct electricity.
+
+ + +
+ + + +
+ + + +
Metals are Malleable



Hammered into shape (bend).
Ductile - drawn into wires.
Both malleability and ductility explained in
terms of the mobility
of the valence electrons
- Page 201
Due to the mobility of the
valence electrons, metals have:
1) Ductility and 2) Malleability
Notice
that the
ionic
crystal
breaks
due to ion
repulsion!
Malleable
Force
+
+ + +
+ + + +
+ + + +
Malleable

Mobile electrons allow atoms to slide
by, sort of like ball bearings in oil.
Force
+ + + +
+ + + +
+ + + +
Ionic solids are brittle
Force
+
+
-
+
+
+
+
-
+
+
Ionic solids are brittle

Strong Repulsion
breaks a crystal apart, due to similar
ions being next to each other.
Force
- + - +
+ - + - + - +
Crystalline structure of metal
 Metals
are arranged in very
compact and
orderly patterns.
Alloys




Alloys - mixtures of 2 or
more elements, at least 1 is a metal
Made by melting a
mixture of elements, then cooling
Brass: an alloy of Cu and Zn
Bronze: Cu and Sn
Why use alloys?
Properties are often superior
to the pure element
 Sterling silver (92.5% Ag, 7.5% Cu) is
harder and more durable than pure Ag,
but still soft enough to make jewelry and
tableware
 Steels are very important alloys
– corrosion resistant, ductility, hardness,
toughness, cost

The
•END
Predicting Ionic Charges
Group B elements: Many transition elements
have more than one possible oxidation state.
Note the use of Roman
Iron (II) = Fe2+
numerals to show charges
Iron (III) = Fe3+
Naming cations

Two methods can clarify when
more than one charge is possible:
1) Stock system – uses roman
numerals in parenthesis to
indicate the numerical value
2) Classical method – uses root
word with suffixes (-ous, -ic)
• Does not give true value
Naming cations
 We
will use the Stock system.
 Cation - if the charge is always the
same (like in the Group A metals) just
write the name of the metal.
 Transition metals can have more
than one type of charge.
– Indicate their charge as a roman
numeral in parenthesis after the name
of the metal (Table 9.2, p.255)
Predicting Ionic Charges
Some of the post-transition elements also
have more than one possible oxidation state.
Tin (II) = Sn2+
Lead (II) = Pb2+
Tin (IV) = Sn4+
Lead (IV) = Pb 4+
Predicting Ionic Charges
Group B elements: Some transition elements
have only one possible oxidation state, such
as these three:
Silver = Ag1+
Zinc = Zn2+
Cadmium = Cd2+
Exceptions:
 Some
of the transition metals
have only one ionic charge:
–Do not need to use roman
numerals for these:
–Silver is always 1+ (Ag1+)
–Cadmium and Zinc are always
2+ (Cd2+ and Zn2+)
Practice by naming these:
 Na1+
 Ca2+
 Al3+
 Fe3+
 Fe2+
 Pb2+
 Li1+
Write symbols for these:
 Potassium
ion
 Magnesium ion
 Copper (II) ion
 Chromium (VI) ion
 Barium ion
 Mercury (II) ion
Naming Anions
Anions
are always the
same charge
Change the monatomic
element ending to – ide
1F
a Fluorine atom will
become a Fluoride ion.
Practice by naming these:
1Cl
3N
Br1O23+
Ga
Write symbols for these:
Sulfide
ion
Iodide ion
Phosphide ion
Strontium ion
Polyatomic ions are…
Groups of atoms that stay together and
have an overall charge, and one name.
 Usually end in –ate or -ite

1-

Acetate: C2H3O2

Nitrate: NO31-

Nitrite:

Permanganate: MnO41-

Hydroxide: OH1- and Cyanide: CN1-?
NO21-
Know Table 9.3 on page 257
2-
Sulfate: SO4
2 Sulfite: SO3


Carbonate: CO32-
Phosphate: PO433 Phosphite: PO3


Chromate: CrO422 Dichromate: Cr2O7

Ammonium: NH41+
(One of
theion
few
If the polyatomic
begins with H, positive
then
polyatomic
Writing Ionic Compound
Formulas
Example: Barium
2+
1.
Write
the
(
)
Ba
NO
nitrate (note the 2
3 2
formulas
for
word
name)
2. Check
to see Now
= Ba(NO3)2
Not
the cation
if
charges
are
balanc
3.
Balance
balan
and anion,
balanced.
ed.
charges
,
if
ced!
including
necessary,
Writing Ionic Compound
Formulas
Example: Ammonium
+) SO 2(
NH
1. Write the
4 2
4
sulfate (note the 2 word
formulas
for
Now
2.
Check to
name)
=
(NH4)2SO4
Not
the
cation
balanc
see
if
3.
Balance
balan
and
anion,
ed.
charges ,are
if
ced!
including
balanced.
necessary,
Writing Ionic Compound
Formulas
Example: Iron (III)3+ Fe Cl
1. Write the
chloride (note the 2 3
formulas for
Now
balan
word
name)
2. Check
to
= FeCl3
Not
the cation
see
if
3.
Balance
balan
and anion,
charges ,are
if
ced!
including
balanced.
necessary,
Writing Ionic Compound
Formulas
Example: Aluminum
3+
21.
Write
the
Al
S
sulfide (note the 2 word
2
3
formulas
for
name)
2. Check to
Now
bala
=
Al
S
2 3
Not
the cation
see
if
3.
Balance
balan
and anion,
charges ,are
if
ced!
including
balanced.
necessary,
Writing Ionic Compound
Formulas
Example: Magnesium
2+ CO 2Mg
1.
Write
the
3
carbonate
formulas for
2. Check to
They
the cation
= MgCO3
see if
are
and anion,
charges are
balanced
including
(note the 2 word name)
Writing Ionic Compound
Formulas
Example: Zinc
2+
(
)
1.
Write
the
Zn
OH
hydroxide (note the 2 2
formulas
for
word
name)
balan
2. Check
to see Now
= Zn(OH)2
Not
the cation
if charges
3.
Balance are balan
and anion,
balanced., if
charges
ced!
including
necessary,
Writing Ionic Compound
Formulas
Example: Aluminum
3+
31. Write the
Al
PO
4
phosphate
formulas
for
2. Check to seeThey ARE
the
cation
= AlPO4
if charges are balanced!
and
anion,
balanced.
including
(note the 2 word name)
Naming Ionic Compounds
 1.
Name the cation first, then anion
 2.
Monatomic cation = name of the
element
Ca2+ = calcium ion
 3.
Monatomic anion = root + -ide
Cl- = chloride
CaCl2 = calcium chloride
Naming Ionic Compounds
(Metals with multiple oxidation states)
 some
metals can form more than one
charge (usually the transition metals)
 use a Roman numeral in their name:
PbCl2 – use the anion to find the charge
on the cation (chloride is always 1-)
Pb2+ is the lead (II) cation
PbCl2 = lead (II) chloride
Things to look for:
1) If cations have ( ), the number
in parenthesis is their charge.
2) If anions end in -ide they are
probably off the periodic table
(Monoatomic)
3) If anion ends in -ate or –ite,
then it is polyatomic
Practice by writing the formula
or name as required…
 Iron
(II) Phosphate
 Stannous Fluoride
 Potassium Sulfide
 Ammonium Chromate
 MgSO4
 FeCl3