Chemical bonds vs.
intermolecular interactions
The three
chemical
bonds
the mix
imbetween
The three
intermolecular
interactions
metallic bonds
covalent bonds
ionic bonds
polar-covalent bonds
~ 400 kJ/mol
~ 400 kJ/mol
~ 400 kJ/mol
visible light
170-290 kJ/mol
ion-dipole
heavy main group dispersion
50-200 kJ/mol
5-100 kJ/mol
FH…H hydrogen bonds
OH…H hydrogen bonds
NH…H hydrogen bonds
room temperature
dipole-dipole interactions
light main group dispersion
~150 kJ/mol
~ 20 kJ/mol
~10 kJ/mol
2.5 kJ/mol
1-5 kJ/mol
< 1 kj/mol
The three
chemical
bonds
the mix
imbetween
The three
intermolelcular
interactions
metallic bonds
covalent bonds
ionic bonds
polar-covalent bonds
~ 400 kJ/mol
~ 400 kJ/mol
~ 400 kJ/mol
visible light
170-290 kJ/mol
ion-dipole
heavy main group dispersion
50-200 kJ/mol
5-100 kJ/mol
FH…H hydrogen bonds
OH…H hydrogen bonds
NH…H hydrogen bonds
room temperature
dipole-dipole interactions
light main group dispersion
~150 kJ/mol
~ 20 kJ/mol
~10 kJ/mol
2.5 kJ/mol
1-5 kJ/mol
< 1 kj/mol
dispersion interactions
the third intermolecular interaction:
strong vs. weak dispersion interactions
Br boiling
point: 59o C
no dipoles and
no hydrogen bonds
in F2, Cl2, Br2 or I2.
F
Br
I boiling
point: 184o C
F boiling
point: -188o C
Cl boiling
point: -34o C
Cl
I
Strong vs. weak dispersion interactions
F
F b.p. -188o C
F−F
Br
Cl
Cl b.p.-34o C
Cl − Cl
Br b.p. 59o C
Br − Br
I
I b.p. 184o C
I−I
The four Lewis structures are all similar.
No dipoles; No ions; No hydrogen bonds
Please
rationalize
the different
boiling points
of the
noble gases.
covalent bonds
ionic bonds
polar-covalent bonds
the one mix
imbetween
~ 400 kJ/mol
~ 400 kJ/mol
~ 400 kJ/mol
visible light
170-290 kJ/mol
ion-dipole
heavy main group dispersion
50-200 kJ/mol
5-100 kJ/mol
FH…H hydrogen bonds
OH…H hydrogen bonds
NH…H hydrogen bonds
room temperature
dipole-dipole
light main group dispersion
~150 kJ/mol
~ 20 kJ/mol
~10 kJ/mol
2.5 kJ/mol
1-5 kJ/mol
< 1 kj/mol
NaCl (solid)
Na+ (aqueous) + Cl- (aqueous)
~200 kJ/mole
~400 kJ/mol
ion-ion bond
~400 kJ/mol
Ion–dipole interaction
~100- 200 kJ/mol.
The three
chemical
bonds
the mix
imbetween
The three
intermolecular
interactions
metallic bonds
covalent bonds
ionic bonds
polar-covalent bonds
~ 400 kJ/mol
~ 400 kJ/mol
~ 400 kJ/mol
visible light
170-290 kJ/mol
ion-dipole
heavy main group dispersion
50-200 kJ/mol
5-100 kJ/mol
FH…H hydrogen bonds
OH…H hydrogen bonds
NH…H hydrogen bonds
room temperature
dipole-dipole interactions
light main group dispersion
~150 kJ/mol
~ 20 kJ/mol
~10 kJ/mol
2.5 kJ/mol
1-5 kJ/mol
< 1 kj/mol
the three chemical bonds, the three intermolecular interactions
and the one mix imbetween
~400
kJ/mole
~400
kJ/mole
I boiling point: 184o C
I
F boiling
point:
-188o C
~200
kJ/mole
The three
chemical
bonds
the mix
imbetween
The three
intermolecular
interactions
metal bonds
covalent bonds
ionic bonds
polar-covalent bonds
~ 400 kJ/mol
~ 400 kJ/mol
~ 400 kJ/mol
visible light
170-290 kJ/mol
ion-dipole
heavy main group dispersion
50-200 kJ/mol
5-100 kJ/mol
FH…H hydrogen bonds
OH…H hydrogen bonds
NH…H hydrogen bonds
room temperature
dipole-dipole
light main group dispersion
~150 kJ/mol
~ 20 kJ/mol
~10 kJ/mol
2.5 kJ/mol
0.5-3 kJ/mol
< 1 kj/mol
heavy main group
dispersion
bond dipole moments
F-H…F
O-H…O
ion-ion
light main
group
dispersion
Qatar
Connecticut corresponds to room temperature
bonds vs. intermolecular interactions
covalent bonds
ionic bonds
polar-covalent bonds
metal bonds
~ 400 kJ/mol
~ 400 kJ/mol
~ 400 kJ/mol
visible light
170-290 kJ/mol
ion-dipole
heavy main group dispersion
50-200 kJ/mol
5-100 kJ/mol
FH…H hydrogen bonds
OH…H hydrogen bonds
NH…H hydrogen bonds
room temperature
dipole-dipole interactions
light main group dispersion
~150 kJ/mol
~ 20 kJ/mol
~10 kJ/mol
2.5 kJ/mol
1-5 kJ/mol
< 1 kj/mol
What are each of the types of interactions/bonds below?
Na+ … Cl-
H3C-SiH3
….
….
H-C≅N
Mg2+…
O2-
N≅C-H
F-H ….OH2
Mg2+… OH2
-
H2Te … TeH2
What interaction holds together the following pairs of
molecules? What is roughly the energy of interaction
in kJ/mole?
a)
b)
two NF3 molecules
two BiF3 molecules
c)
two F2 molecules
d)
two HF molecules
e)
an H2O molecule and an HF molecule
f)
two CH4 molecules
covalent bonds
ionic bonds
polar-covalent bonds
metallic bonds
~ 400 kJ/mol
~ 400 kJ/mol
~ 400 kJ/mol
visible light
170-290 kJ/mol
ion-dipole
heavy main group polarization
50-200 kJ/mol
5-100 kJ/mol
FH…H hydrogen bonds
OH…H hydrogen bonds
NH…H hydrogen bonds
room temperature
dipole-dipole (< 2 D, Dc 1st-2nd row)
light main group polarization
~150 kJ/mol
~ 20 kJ/mol
~10 kJ/mol
2.5 kJ/mol
0.5-3 kJ/mol
< 1 kj/mol
heavy main group dispersion
Are X and Y
1st and 2nd
row elements?
no
Do heavy main group
interactions exist?
yes
yes
Do F-H…F
bonds exist?
no
Do O-H…O
bonds exist?
yes
Do N-H…N bonds
exist?
no
yes
yes
covalent bond
no
F-H…F
light main
group
polarization
O-H…O
yes
N-H…N
Calculate Dc
Is Dc < 0.5 Debye?
dipole-dipole interaction
yes
Is Dc > 1 Debye?
What interaction holds together the following pairs of
molecules? What is roughly the energy of interaction
in kJ/mole?
a)
b)
two NF3 molecules
two BiF3 molecules
c)
two F2 molecules
d)
two HF molecules
e)
an H2O molecule and an HF molecule
f)
two CH4 molecules
For now compare boiling
points for molecules with
roughly the same
molecular mass.
Why do the boiling
points occur in the
order in which they
do?
Where would formic
acid, HCO2H with
molecular weight
46 g/mol appear on
this boiling point
chart?
How would CH3SeSeCH3 and I2
approach one another?
How would RSeSeR and I2 approach one another?
Salad dressing is composed of oil and vinegar (that is
hydrocarbons, CH3(CH2)nCH3, water, and acetic acid,
CH3COOH.
Why do oil and vinegar not mix?
A typical soap compound is sodium stearate.
Why is soap good at removing the oil from
the skin?
sodium stearate
A typical soap compound is sodium stearate.
Why is soap good at removing the oil from
the skin?
sodium stearate
rule: like adheres to like.
two additional factors which control intermolecular interactions (1) size
The larger the molecule,
the greater number of similar
intermolecular interactions the
molecule can have.
and (2) shape.
The boiling point depends upon the number of atoms on the
molecule’s surface available for intermolecular interactions.
determining molecular shape:
ionic bonds vs. covalent bonds
Determine molecular shape of:
a)
NF3
b)
MgO
c)
CH3COCH3
d)
TiO2
Determine molecular shape of:
NF3
MgO
CH3COCH3
TiO2
Mooser-Pearson
What can you deduce about the molecular shape of
the following ions/compounds?
a)
CaS
b)
Si
c)
SiF62-
d)
NaI3
e)
HC(CH3)3
review slie 1
What are each of the types of interactions/bonds below?
Na+ … Cl-
H3C-SiH3
….
….
H-C≅N
Mg2+…
O2-
N≅C-H
F-H ….OH2
Mg2+… OH2
-
H2Te … TeH2
What interaction holds together the following pairs of
molecules? What is roughly the energy of interaction
in kJ/mole?
a)
b)
two NF3 molecules
two BiF3 molecules
c)
two F2 molecules
d)
two HF molecules
e)
an H2O molecule and an HF molecule
f)
two CH4 molecules
review slie 2
What can you deduce about the molecular shape of
the following ions/compounds?
a)
CaS
b)
Si
c)
SiF62-
d)
NaI3
e)
HC(CH3)3
review slie 3
homework
Two proportionality questions
a) If a series of chemically similar molecules (made from the
same combination of elements) are all shaped like spheres,
what is the proportionality relation between molecular mass
and boiling point?
b) If a series of chemically similar molecules (made from the
same combination of elements) are all shaped like chains,
with almost every bond on the surface of the molecule,
what is the proportionality relation between molecular mass
and boiling point?