Unit 5 Topic 4: Bonding
CDO IB Chemistry SL
Assessment Statements
I.
Ionic Bonding
i.
ii.
iii.
iv.
v.
vi.
III.
Describe an ionic bond as an attraction between opposite charges ions
Describe how ions are formed as a result of electron transfer
Deduce which ions are formed for elements in Group 1, 2, 3, 5, 6, 7
State that transition elements can form more than one ion
Deduce if a compound of two elements would be ionic
Describe the lattice structure of ionic compounds
Covalent Bonding
i.
ii.
iii.
iv.
v.
vi.
Describe how a covalent bond is formed as a result of electron sharing
Describe the Lewis structures of molecules or ions for up to 4 electron pairs
Describe and state the relationship between number of bonds and length and strength
Predict the relative polarity of bonds
Describe the shape of molecules using the VSEPR theory
Predict molecular polarity
Unit 5CDO IB Chemistry SL :Bonding Christman
IV. Intermolecular Forces
i.
Describe the types of IMF and how they arise
ii. Describe how IMF effect boiling points
1
Chemical Bonds

Three basic types of bonds
o
Ionic

o
Covalent

o
Metallic


Polar vs. Non-Polar
•
Ionic –
•
Polar Covalent –
•
Non-Polar Covalent –
•
Simply put:

Ionic –

Polar Covalent –

Non-Polar Covalent –

Noble gases rarely form compounds because:
o
o
Eight electrons
o
It requires a lot of
Unit 5CDO IB Chemistry SL :Bonding Christman
Bond Formation and Noble Gases
2
The Octet Rule
•
Octet Rule –
•
Elements in the main groups –
•
Obtaining an octet -
•
Duet Rule –
Formation of Chemical Bonds
•
Valence electrons –
•
Chemical bond –
•
Bonds form –
Covalent Bonding
•
Electrons involved in the bond are
•
Covalent bonding generally
•
Two nonmetals -
•
Bonds resulting from this sharing are called -
•
Multiple bonds -
Unit 5CDO IB Chemistry SL :Bonding Christman
Types of Covalent Bonds
3
Lewis Structures
•
Lewis structures are
Drawing Lewis Structures
1. Determine the arrangement of the atoms in the compound with respect to each other and draw
a skeletal structure.
2. If the compound is binary, the first element written down is usually the central atom (hydrogen is
an exception to this).
3. With a ternary compound (one with three kinds of elements) the middles atom in the formula is
usually the central one.
4. Determine the total number of valence electrons.
5. Subtract two electrons for each bond in the skeletal structure.
6. Determine how many electrons are required for each element to have a total of eight (there are
several exceptions to this rule).
7. If a sufficient number of electrons are available, distribute the remaining electrons around the
element symbols.
8. If a sufficient number is not available, add additional bonds making certain to subtract the
electrons used. (Multiple bonds often occur among the atoms C, N, and O.
Examples
CN-
H2SO4
Unit 5CDO IB Chemistry SL :Bonding Christman
NCl3
4
Resonance structures
•
In compounds with multiple bonds-
•
Resonance structures-
•
Actually –
Example
Ozone, O3

Some structures will have less than an octet –

Examples

BeCl2

BF3
Unit 5CDO IB Chemistry SL :Bonding Christman
The Octet Rule is not Always Followed
5
Dative Bonds

Dative Bond –

Examples:

H3O+

NH4+

CO
•
Bond
•
Bond
•
Bond
Bond Length
•
An average bond length for
•
As the number of bonds between
Unit 5CDO IB Chemistry SL :Bonding Christman
Properties of Bonds
6
Bond Strength
•
Bond strength is usually
•
Generally – increase in the number of
Polar Bonds
•
When two atoms share
•
When a polar bond exists between two atoms,
Polar Covalent Bonds

The greater the
Example
Geometry of Simple Molecules

Electrons repulsion –

Electron pairs -
Unit 5CDO IB Chemistry SL :Bonding Christman
Determine and show if each of the following bonds are polar
7
Valence Shell Electron Pair Repulsion (VSEPR)

Degree of repulsion -
•
•
lone pair-lone pair –
•
lone pair-bonding pair
•
bonding pair-bonding pair –
Multiple bonds =
Electron Domain Geometry
•
Electron Geometry –
•
A – designates
•
X – designates the number of
Electron Domain Geometry Parent Structures
Examples – Electron Geometry
•
CH4
ELECTRON DOMAIN
GEOMETRY
BOND ANGLE
Unit 5CDO IB Chemistry SL :Bonding Christman
PARENT STRUCTURE
8
•
OCN-
•
SO3
Molecular Geometry
•
Molecular Geometry –
•
X–
•
E–
Electron Geometry and Molecular Geometry Summary
Example
•
CCl4
ELECTRON
DOMAIN
ATTACHED
ATOMS
LONE
ELECTRON PAIR
MOLECULAR
GEOMETRY
Unit 5CDO IB Chemistry SL :Bonding Christman
PARENT
STRUCTURE
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•
SCl2
•
H3O+
Molecular Polarity
•
Molecular Polarity is a function of both
•
If polar bonds are
•
If the polar bonds are
Molecular Polarity
Molecules will be polar if
a)
bonds are
b)
the molecule is
Example: Polar or Nonpolar?
Unit 5CDO IB Chemistry SL :Bonding Christman
Compare CO2 and H2O. Which one is polar?
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Example: Polar or Nonpolar?
Are the Molecules Polar or Non- Polar: BF3, Cl2CO, and NH3.
.
Intermolecular Forces
The attractions between molecules that hold
Intermolecular Forces
•
They are, however, strong enough to
Unit 5CDO IB Chemistry SL :Bonding Christman
•
11
van der Waals Forces
•
These intermolecular forces, which are all
•
•
•
Dipole-Dipole Interactions
•
Molecules that have
o
The positive end of one is
o
These forces are only
Dipole-Dipole Interactions
The more
London Dispersion Forces
•
Nonpolar molecules do not have permanent dipoles.
London Dispersion Forces
•
London dispersion forces,
Unit 5CDO IB Chemistry SL :Bonding Christman
•
12
London Dispersion Forces
•
These forces are
•
The tendency of an
Factors Affecting London Forces
•
The shape of the molecule affects the strength of
•
This is due to the
Factors Affecting London Forces
•
The strength of dispersion forces
•
Larger atoms have
•
The dipole-dipole interactions
•
We call these interactions
•
Although it is called a bond it is
Hydrogen Bonding
•
Hydrogen bonding arises in part from the
Unit 5CDO IB Chemistry SL :Bonding Christman
Hydrogen Bonding
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Determination of Intermolecular Forces
1. Draw the
2. Determine if the molecule
Determination of Intermolecular Forces
•
Nonpolar molecule =
•
Polar molecule =
•
Polar molecules with hydrogen directly bonded to fluorine, oxygen or nitrogen =
Example
Determine the intermolecular forces for each of the following molecules:
carbon tetrachloride
ammonia
carbon dioxide
Unit 5CDO IB Chemistry SL :Bonding Christman
water
14
phosphorus trichloride
Layering of IMF’s
•
Usually IMF’s are described in terms of the strongest one present

Strongest –

Medium –

Weak –
Properties of solids
Types of Solids
•
Ionic –
•
Covalent – Giant –
•
Covalent – Molecular –
•
Metallic –
Bonding
Ionic
Metallic
Giant
Covalent
Molecular
Covalent
Lattice
Forces
BP
Volatility
H vap
Unit 5CDO IB Chemistry SL :Bonding Christman
Physical Properties and IMF
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
Volatility –

H vap –
Allotropes of Carbon

Allotrope –

Carbon has 3 Allotropes
Silicon and Silicon Dioxide

Silicon –

Silicon Dioxide –

Solubility –

Axiom –

Reasoning –
Unit 5CDO IB Chemistry SL :Bonding Christman
Solubility
16

NaCl and Water

Methane and NaCl
Unit 5CDO IB Chemistry SL :Bonding Christman

Examples
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Unit 5: Lewis Structures
Problem Set 5-1
Draw the Lewis structures for each of the following molecules. Show resonance structures if appropriate.
1. HOCl
2. NH4+
3. C2H6 (There are 2 central C atoms)
4. SO3
5. H2CO
6. HCCCH3 (There are 3 central C atoms)
7. ICl
8. CS2
9. NO2-
Unit 5CDO IB Chemistry SL :Bonding Christman
10. SO32-
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Unit 5: Polar Bonds
Problem Set 5-2
Difference in electronegativity
1.7
Ionic
100%
Bonding
between
.4
Polar-covalent
bond
50%
5%
Percentage Ionic character
More
electronegative
element and value
Less
electronegative
element and value
Sulfur and
Hydrogen
Sulfur and
cesium
Chlorine and
bromine
Calcium and
chlorine
Oxygen and
hydrogen
Nitrogen and
hydrogen
Iodine and
iodine
Copper and
sulfur
Hydrogen and
fluorine
Carbon and
oxygen
For the following polar bonds indicate the ends of the dipole
1. H – O
2. C – F
3. Si – O
0
Non-polar
covalent
bond
0%
Difference in
electronegativity
Bond Type
Unit 5CDO IB Chemistry SL :Bonding Christman
4.0
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Unit 5: Geometry
Problem Set 5-3
Draw the Lewis structures and predict the electron domain and molecular geometry, include the bond angle
1. SnCl3
2. NH4+
3. O3
4. SO3
5. NO3-
7. PO43-
8. XeO4
9. SF2
10. NH3
Unit 5CDO IB Chemistry SL :Bonding Christman
6. ClO4-
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Unit 5: Molecular Polarity
Problem Set 5-4
For each of the following molecules, draw the correct Lewis structure; determine the electron domain geometry,
molecular geometry and the polarity of the molecule
1. Sulfate ion
2. Water
3. Carbon dioxide
4. Ammonia
5. Nitrate ion
6. Carbonate ion
7. Ozone
8. Boron trichloride
9. CH4
Unit 5CDO IB Chemistry SL :Bonding Christman
10. Cl2CF2
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Unit 5: IMF
Problem Set 5-5
For each pair of compounds listed below, identify the compounds intermolecular forces and determine which of
the pair has the higher boiling point.
a. Br2 or I2
b. NH3 or NCl3
c. NH3 or CH4
d. CH4 or CCl4
e. He or Ar
f.
Cl2 or H2
g. H2O or H2S
h. CH4 or SnH4
i.
NH3 or PH3
j.
AsH3 or SbH3
k. Ca(OH)2 or H2O
KCl or Cl2
m. F2 or Cl2
n. C2H6 or C4H10
Unit 5CDO IB Chemistry SL :Bonding Christman
l.
22
Unit 5: Properties of Solids
Problem Set 5-6
Match each of the following descriptions with one of the following (some of the descriptions might apply to
more than one kind of bond):
1
2
3
4
5
6
7
8
9
10
11
12
13
14
14
16
17
18
19
20
21
22
23
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Ionic Bonds
Network Covalent Bonding
Molecular Polar covalent bonding
Molecular Non-polar covalent bonding
Metallic Bonding
Hard, high melting and boiling points due to strong directional bonds.
Hard, brittle, high melting points due to crystal lattice
Bond formed through electron transfer from one atom to another
Structure formed from electrostatic attraction between atoms
Bond formed due to sharing of electrons between atoms of high electronegativity
Strong bonds form a hard but malleable structure due to delocalization of electrons
Positive ions in an electron sea
High conductivity due to mobility of electrons
Conducts electricity in the molten state or when dissolved in water
Soluble in water
The boiling point of these molecules increases as the mass of the molecule increases
The melting point of these molecules increases as the surface area of the molecule increases
The higher the charge on the cation, the stronger the bond
The molecules contain permanent dipoles
These molecules experience only induced or temporary dipoles
These molecules may experience hydrogen bonding
This kind of bonding results in molecules with definite shapes
Example: ceramic, glass, sand
Example: sulfur, diamond, buckyball
Example: water, ammonia, CH3CH2OH
Example: Carbon dioxide, Sulfur trioxide
Example: KF, NaBr, CaO, MgCO3
Example: wax, oil
Example: Chlorine, Iodine
Unit 5CDO IB Chemistry SL :Bonding Christman
A.
B.
C.
D.
E.
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Unit 5: Solubility
Problem Set 5-7
1)
water ________________________________________
2)
carbon tetrachloride ____________________________
3)
ammonia _____________________________________
4)
carbon dioxide_________________________________
5)
phosphorus trichloride ___________________________
6)
nitrogen _______________________________________
7)
ethane (C2H6) __________________________________
8)
acetone (CH2O) _________________________________
9)
methanol (CH3OH) _______________________________
10)
borane (BH3) ___________________________________
Unit 5CDO IB Chemistry SL :Bonding Christman
Give the strongest intermolecular force present for each of the following compounds and the kinds of
solvent (polar/non-polar) that they will dissolve in?
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