Gen Concepts Chemical Bonding Sheet
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1
2
3Compound
Molecular
Ionic
Conducts as Solid
NO
NO
Conducts as Liquid
NO
YES
Conducts in Solution
NO
YES
Conducts as Gas
NO
YES
5 • Chemical Bonding: Gen Concepts
Some Properties of
Hardness
soft
hard
Ionic and Molecular Compounds
MP / BP
low
high
(1 of 12)
Bonding
covalent
ionic
Examples
He, CH
, CO
,
NaCl, KI,
4
2
C
H
O
AgNO
6
12
6
3
Lewis symbols conisist of the atomic symbol surrounded by
valnece electrons. The four sides represent the four valence
orbitals. Atoms are usually shown in their excited states (II,
III, IV)
5 • Chemical Bonding: Gen Concepts
Li
Be
B C
N
O
F
Ne
Lewis Symbols of Atoms and Ions
(2 of 12)
Ions include brackets. Positive ions show no valence
electrons while negative ions usually have an octet.
+
2+
2–
[Li]
[Mg]
[ O ]
Many ions can be explained because they have gained or lost
electrons and attain a noble gas configuration. For example:
3–
2–
–
+
2+
P
S
Cl
Ar K
Ca
2
2
6
2
6
all have the same electron arrangement: 1s
2s
2p
3s
3p
5 • Chemical Bonding: Gen Concepts
A pseudonoble gas configuration is:
The Ionic Bond
2
2
6
2
6
10
1s
2s
2p
3s
3p
3d
Noble and Pseudonoble Gas Configurations
+
2+
3+
4+
(3 of 12)
This is found in Cu
Zn
Ga
and Ge
Similar configurations are found in the next two periods.
The importance of this configuration is that there is more
than one reason why ions form what they do. Many ions are
not explained.
Know the 5 steps that can be thought to occur when an ionic
bond forms. Note whether each is exo- or endothermic...
whether a larger energy helps or hinders the bond formation.
(g) → LiF(s)
Overall:
Li(s) + 1/2F
2
5 • Chemical Bonding: Gen Concepts
Li(s) + NRG → Li(g)
Factors that Influence
1.
heat of vaporization
(g) + NRG → F(g)
2.
heat of decomposition
1/2F
the Formation of Ionic Bonds
2
Li(g) + NRG → Li
+
–
(4 of 12)
3.
ionization energy
(g) + e
→ F
–
–
4.
electron affinity
F(g) + e
(g)
(g) → LiF(s)
+
–
5.
lattice energy
Li
(g) + F
Large energy values for 1,2,3 hinder ionic bond formation.
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