Ionic & Metallic Bonding
Chapter 7
7.1 Ions
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Ions are atoms that have gained or lost
electrons….
Have a net electrical charge
Cations & Anions
Valence electrons are lost when cations are
formed
Electrons are gained by the valence shell
when anions are formed.
Valence Electrons & Core Electrons
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Ve’s are the outermost electrons
In the highest s and p sublevels
Core electrons are the remaining inner
electrons
1s1
1s2 2s2 2p2
1s2 2s2 2p6 3s2 3p5
1s2 2s2 2p3
1s2 2s2 2p4
1s2 2s2 2p6 3s2 3p6 4s1
Valence electrons
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Number of valence electrons largely
determines properties of the element and its
group
Elements within a group have the same
number of valence electrons…Why?
Number of ve’s indicated by the group A
group numbers, IA, IIA, IIIA, etc.
Or count left to right, skipping transition
metals
Valence Electrons
1s1
1s22s22p2
1s22s22p3
1s22s22p4
Lewis (Electron Dot) Structures
Valence electrons represented as dots
What is the octet rule?
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Noble gases are extremely unreactive, i.e.
very stable
When forming ions or compounds,
representative elements (Group A) gain,
lose, or share electrons in order to achieve a
noble gas electron configuration
i.e. an octet, ns2np6
Metals vs. Nonmetals
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Metals tend to give up ve’s to achieve an
octet
Nonmetals tend to gain or share ve’s to
achieve an octet
Formation of Cations
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When Na loses its valence electron, there is an octet
in the next lowest energy level
Using electron dot (Lewis) structures…
Na∙ → Na+ + e-
Formation of Cations
The
electron configuration of the sodium ion is the same as
that of a neon atom.
Transition Metals
Do not follow the octet rule
 “Pseudo-noble gas” configuration
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Formation of Anions
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Non-metals tend to gain ve’s to achieve an octet
(noble gas e- configuration)
Formation of Anions
Using electron dot (Lewis) structures…
Formation of Anions
Both
a chloride ion and the argon atom have an octet of
electrons in their highest occupied energy levels.
How can you predict the charge of a
monatomic ion?
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Determine number
of ve’s
Representative
elements will gain or
lose the least
number of ve’s to
achieve an octet
Predict the charge of
the aluminum ion.
Can you do it? Use the octet rule
to predict the charge B and S ions
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How many valence electrons does it have?
Is it a metal or non-metal?
Will it gain or lose electrons?
If so, how many?
Write an equation using Lewis structures to
show the formation of
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The boron ion (Examples pp. 189-190)
The sulfide ion (Examples pp. 191-192)
Common Anions
7.2 Ionic Compounds
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If ionic compounds are
composed of (+) and (-)
ions, what type of
elements are most likely
to be found in them?
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What types of elements
form cations?
What types of elements
form anions?
Usually composed of a
metal and non-metal
Ionic Bonds & Ionic Compounds
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Ionic bonds are electrostatic forces that hold
cations and anions together
Ionic compounds are composed of cations
and anions
Are electrically neutral
Ionic Bonds
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Electrostatic forces of attraction between oppositely
charged ions
Very strong bonds
Formula Unit
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Chemical formula for an ionic compound
Lowest whole number ratio of ions in the
compound producing an electrical neutrality
What is the formula unit for…
Sodium chloride
Magnesium chloride
Sodium sulfide
Magnesium oxide
What are the properties of ionic
compounds?
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Solids
Brittle
High melting points
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Evidence of very strong bonds
3D arrangement of ions
Coordination number
Electrolytes (conduct electric current when
dissolved in water or molten
Crystalline Solids:
Specific 3D Arrangement of Ions
“crystal lattice”
Coordination Number
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Number of ions
surrounding an
oppositely charged ion
High melting temperatures (mp)
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Because ionic bonds are very strong, it takes
much energy to break them
Therefore, their mp’s are high
Sample mp’s of ionic compounds
Compound
Name
Formula Unit
mp (ºC)
NaCl
801 (1473 F)
MgO
2852 (5165 F)
LiF
845 (1553 F)
Sr(NO3)2
570 (1058 F)
KNO3
334 (633 F)
Electrolytes
Conduct electricity when dissolved or in a molten
state
Electrical
current is a
movement of
charge
Because ions
are free to
move in the
molten or
aqueous
state
Electrolytes
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Substances that conduct electrical current
when dissolved (aqueous state)
Include ionic substances and some non-ionic
(molecular) substances
Strength of electrolyte corresponds to degree
of dissociation or ion formation when in water
Electrolytes
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Strong electrolytes fully dissociate into ions
when dissolved in water
NaCl(s) 100%

 Na  (aq)  Cl (aq)
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Weak electrolytes partially dissociate
C2 H 4O2 
 C2 H3O2
100%
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


H
(aq)
(aq)
Non-electrolytes do not form ions when
dissolved in water
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most non-ionic substances
E.g. sugar (C12H22O11)
7.3 Bonding in Metals: Structure of
Metals
“Electron sea” model of
metals
valence electrons are free to
move about in metals
Metallic bonds: attraction
between metal cations and
core electrons of other
cations
Metallic Bond
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Cations are attracted to
electrons of other
atoms
Valence electrons are
free to move from atom
to atom
Properties of Metals are due to the
Structure of Metals
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Ductility
Malleability
High electrical conductivity
Luster
High thermal conductivity
Electron sea model of metals
https://www.youtube.com/wat
ch?v=c4udBSZfLHY
Compare Properties of Metals and
Ionic Compounds
Property
Metals
Ionic
Compounds
Malleability &
ductility
High
Brittle
Electrical
conductivity as
solid
High
None
Luster
High
Low or none
Thermal
conductivity
High
Low or none
Structure of Metals and Ionic Cpds
Explains Their Different Properties
Crystal Structure of Metals
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Metal atoms arranged in orderly, compact patterns
Unit Cell & Crystal Lattice
Alloys
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Homogeneous mixtures of which at least
one component is a metal
Alloys are examples of solid solutions
Have superior properties to the pure metal,
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hardness, tensile strength, durability, etc.
Some bicycle frames are made of
titanium alloys that contain
aluminum and vanadium.
Steels are Alloys
There are many alloys of
steel used for different
applications
Vocational & Professional
Opportunities…
Metallurgy & metallurgical
engineering
Welding & welding
engineering