Chemical Bonding
I. Introduction to
Bonding
I
II
III
IV
A. Vocabulary
Chemical Bond
attractive force between atoms or ions
that binds them together as a unit
bonds form in order to…
decrease potential energy (PE)
increase stability
A. Vocabulary
CHEMICAL FORMULA
IONIC
COVALENT
Formula
Unit
Molecular
Formula
NaCl
CO2
A. Vocabulary
COMPOUND
2 elements
Binary
Compound
NaCl
more than 2
elements
Ternary
Compound
NaNO3
A. Vocabulary
ION
1 atom
2 or more atoms
Monatomic
Ion
Polyatomic
Ion
+
Na
NO3
-
B. Types of Bonds
IONIC
COVALENT
Bond
Formation
e- are transferred from
metal to nonmetal
e- are shared between
two nonmetals
Type of
Structure
crystal lattice
true molecules
Physical
State
solid
liquid or gas
Melting
Point
high
low
Solubility in
Water
yes
usually not
Electrical
Conductivity
yes
(solution or liquid)
no
Other
Properties
odorous
B. Types of Bonds
METALLIC
Bond
Formation
e- are delocalized
among metal atoms
Type of
Structure
“electron sea”
Physical
State
solid
Melting
Point
very high
Solubility in
Water
no
Electrical
Conductivity
yes
(any form)
Other
Properties
malleable, ductile,
lustrous
C. Bond Polarity
Most bonds are
a blend of ionic
and covalent
characteristics.
Difference in
electronegativity
determines bond
type.
C. Bond Polarity
Electronegativity
Attraction an atom has for a shared pair
of electrons.
higher e-neg atom  lower e-neg atom +
C. Bond Polarity
Electronegativity Trend (p. 151)
Increases up and to the right.
C. Bond Polarity
Nonpolar Covalent Bond
e- are shared equally
symmetrical e- density
usually identical atoms
C. Bond Polarity
Polar Covalent Bond
e- are shared unequally
asymmetrical e- density
results in partial charges (dipole)
+


C. Bond Polarity
Nonpolar
Polar
Ionic
View Bonding Animations.
C. Bond Polarity
Examples:
Cl2
3.0-3.0=0.0
Nonpolar
HCl
3.0-2.1=0.9
Polar
NaCl
3.0-0.9=2.1
Ionic
Chemical Bonding
II. Ionic Compounds
I
II
III
IV
A. Energy of Bond Formation
Lattice Energy
Energy released when one
mole of an ionic crystalline
compound is formed from
gaseous ions
B. Lewis Structures
Covalent – show sharing of eIonic – show transfer of e-
B. Lewis Structures
Covalent – show sharing of eIonic – show transfer of e-
C. Ionic Nomenclature
Ionic Formulas
Write each ion, cation first. Don’t show
charges in the final formula.
Overall charge must equal zero.
If charges cancel, just write symbols.
If not, use subscripts to balance
charges.
Use parentheses to show more than one
polyatomic ion.
Stock System - Roman numerals indicate
C. Ionic Nomenclature
Ionic Names
Write the names of both ions, cation first.
Change ending of monatomic ions to -ide.
Polyatomic ions have special names.
Stock System - Use Roman numerals to
show the ion’s charge if more than one is
possible. Overall charge must equal zero.
C. Ionic Nomenclature
Consider the following:
Does it contain a polyatomic ion?
-ide, 2 elements  no
-ate, -ite, 3+ elements  yes
Does it contain a Roman numeral?
Check the table for metals not in
Groups 1 or 2.
No prefixes!
C. Ionic Nomenclature
Common Ion Charges
1+
0
2+
3+ NA 3- 2- 1-
C. Ionic Nomenclature
potassium chloride
K+ Cl-

KCl
magnesium nitrate
Mg2+ NO3-

Mg(NO3)2
copper(II) chloride
Cu2+ Cl-

CuCl2
C. Ionic Nomenclature
NaBr
sodium bromide
Na2CO3
sodium carbonate
FeCl3
iron(III) chloride
Chemical Bonding
III. Molecular Compounds
I
II
III
IV
A. Energy of Bond Formation
Potential Energy
based on position of an object
low PE =
high stability
A. Energy of Bond Formation
Potential Energy Diagram
attraction vs. repulsion
no interaction
increased
attraction
A. Energy of Bond Formation
Potential Energy Diagram
attraction vs. repulsion
increased
repulsion
balanced attraction
& repulsion
A. Energy of Bond Formation
Bond Energy
Energy required to break a bond
Bond
Energy
Bond
Length
A. Energy of Bond Formation
Bond Energy
Short bond = high bond energy
B. Lewis Structures
Electron Dot Diagrams
show valence e- as dots
distribute dots like arrows
in an orbital diagram
4 sides = 1 s-orbital, 3 p-orbitals
EX: oxygen
2s
2p
O
X
B. Lewis Structures
Octet Rule
Most atoms form bonds in order to
obtain 8 valence eFull energy level stability ~ Noble
Gases
Ne
B. Lewis Structures
Nonpolar Covalent - no charges
Polar Covalent - partial charges
+
+
C. Molecular Nomenclature
Prefix System (binary compounds)
1. Less e-neg atom
comes first.
2. Add prefixes to indicate # of atoms.
Omit mono- prefix on first element.
3. Change the ending of the
second element to -ide.
C. Molecular Nomenclature
PREFIX
monoditritetrapentahexaheptaoctanonadeca-
NUMBER
1
2
3
4
5
6
7
8
9
10
C. Molecular Nomenclature
CCl4
carbon tetrachloride
N2O
dinitrogen monoxide
SF6
sulfur hexafluoride
C. Molecular Nomenclature
arsenic trichloride
AsCl3
dinitrogen pentoxide
N2O5
tetraphosphorus decoxide
P4O10
C. Molecular Nomenclature
The Seven Diatomic Elements
Br2 I2 N2 Cl2 H2 O2 F2
H
N O F
Cl
Br
I