CHAPTER 13
LIQUIDS & SOLIDS
CHM 130
GCC
13.1
Properties of
Liquids
1. Liquids take the shape of their container,
but have a constant volume.
2. Different liquids flow at different rates.
(Viscosity)
3. Liquids are not compressible since the
atoms/molecules are close together.
4. Liquids have much higher densities than
gases.
5. Soluble liquids will mix uniformly together.
13.2 IMF
BONDS hold atoms together within a
single molecule. (Polar and nonpolar covalent bonds)
Review polar and nonpolar bonds and molecules
INTERMOLECULAR FORCES (IMF)
hold molecules together in liquids and solids.
–IMF are always weaker than bonds!
Bonds vs IMF
In one HCl molecule what holds the H to the Cl is
a polar covalent bond.
H-Cl
In a sample with thousands of HCl
molecules what holds them together is IMF.
H-Cl
H-Cl
INTERMOLECULAR FORCES
1) Dispersion (London) Forces
2) Dipole-Dipole Forces
3) Hydrogen Bond Forces
H bond forces is NOT a bond!!!
Dispersion (London) Force
• Temporary attraction between nonpolar
molecules or atoms that form when two of
them get real close.
• Electrons get pushed to one side so results in
a temporary partial negative charge (d-) that
disappears when the molecules separate.
• Often seen in gases since very little attraction
between nonpolar molecules – thus they are
not close together but far apart (gas)!!!
• Bigger molecules, more electrons, more
London Force.
Two Nonpolar Molecules
Dipole – Dipole forces
• Exists between polar molecules. (have partial
d+ and d– ends)
• The partial d+ end of one molecule is
attracted to the partial d- end of a second
molecule (opposites attract).
d-
d+
H
Cl
d-
d+
H
Cl
Dipole-Dipole Forces
• Stronger than London forces.
• Must be POLAR molecules.
Hydrogen Bonding Force
• An especially strong dipole force between
molecules containing the very polar H-F,
H-O or H-N bonds.
• The d+ H end of one molecule is attracted
to the d - N/O/F end of a second molecule.
H Bond Force
• Strongest type of IMF, yet still much
weaker than a bond.
Polar covalent bonds
Indicate the strongest type of IMF between
these molecules:
Polar or
Nonpolar?
CO2
PF3
HF
CH4
nonpolar
Strongest Intermolecular
Force
London
polar
Dipole - Dipole
polar
H Bond Force
nonpolar
London
Bonds vs Forces
• Bonds
– Ionic bond (holds metal/nonmetal ions together)
– Polar Covalent Bond (e- shared unequally
between nonmetal atoms)
– Nonpolar Covalent Bond (e- shared equally)
• Forces
– London (nonpolar molecules)
– Dipole Dipole (polar molecules)
– H bond Force (H bonded to NOF)
Coulomb’s Law Review
• Opposite charges attract according to Coulomb’s
Law
• The electrostatic attraction between two charges is
proportional to the charge magnitude (q) and
inversely proportional to the distance (r) squared.
• F = ke(q1q2 / r2)
• Larger charge means stronger attraction!
• Ionic bonds very strong cause charges are
complete +1, +2, +3 charges. Like in NaCl.
• Dipole dipole IMF much weaker cause charges are
much less than +1. Remember polar bonds are
partially d+ and d -.
Choose the bond or IMF described for each below:
Bond or IMF?
What holds these together???
What holds the atoms together in one ammonia
NH3 molecule?
What is holding the H and O atoms together in water?
What is holding three HCl molecules together?
What is holding the ions together in salt NaCl.
What is holding four H2O molecules together.
What holds nitrogen gas molecules to each other?
What is holding the O’s together in an oxygen gas
molecule?
What is holding two ammonia molecules
together?
Answers on Next Slide
Choose the bond or IMF described for each below:
Bond or IMF?
What holds these together???
Polar covalent
bonds
What holds the atoms together in one ammonia,
NH3, molecule?
Polar covalent
bonds
What is holding the H and O atoms together in water?
Dipole Dipole
forces
What is holding three HCl molecules together?
Ionic bonds
What is holding the ions together in salt NaCl.
H bonding
forces
What is holding four H2O molecules together.
London forces
What holds nitrogen gas molecules to each other?
Nonpolar
covalent bonds
What is holding the O’s together in an oxygen gas
molecule?
H bonding
forces
What is holding two ammonia molecules
together?
13.3 Vapor Pressure (VP)
• At the surface of a liquid some
molecules have enough kinetic energy
to break the attractive forces (IMF) with
neighboring molecules.
• They escape from the liquid and go into
the gas state.
• If no lid, they float away with air
molecules.
• If there is a lid, a pressure develops.
Vapor Pressure is the pressure exerted by gas
molecules above a liquid in a closed container.
• Stronger IMF  higher or lower VP ???
–Lower. Stronger attractions mean less likely to
break away from surface and go into gas state (so
less gas so less pressure)
Which has
weaker
IMF? A
Higher VP?
A
Balloons are attached to
flasks containing water
and ether. Which has
stronger IMF? Higher
VP?
Water has stronger IMF
and it stays together as
liquid. Ether has low IMF,
molecules break away
into gas filling balloon, so
it has higher VP.
Boiling Point (bp)
Temperature where liquid changes to gas.
Stronger IMF = higher or lower bp ??
– Higher
– Strong IMF means molecules held tightly
together so more energy is required to pull
them apart so need higher temp.
Surface Tension
• Surface molecules hold on to each other, this
is why liquids make drops / beads.
• Stronger IMF = high or low surface tension?
High – stronger IMF means molecules are
attracted so molecules stay together with more
surface tension.
Surface Tension
Which drop of liquid has higher IMF
& surface tension?
A, because molecules held together and did not
spread out very much
VISCOSITY
The resistance of a liquid to flow.
• Oil flows slowly  high viscosity
• Vodka flows rapidly
 low viscosity
Stronger IMF  higher or lower viscosity ???
Higher because molecules held
together so flow is hindered and slow.
Let’s compare ammonia
and fluorine. First what
IMF do they have?
NH3 has H bonding
force, F2 gas has
London force
Questions
1. Which has stronger IMF?
2. Which has the lower bp?
3. Which is polar?
4. Which has higher VP?
5. Which is least viscous (if liquid)?
6. Which has more surface tension?
Ammonia
Fluorine
Ammonia
Fluorine
Fluorine
Ammonia
Fill in the blanks with increase
or decrease
• As IMF increase:
increases
– Viscosity ____________
increases
– Bp ___________
increases
– Surface tension ___________
decreases
– Vapor pressure ___________
13.4 Properties of Solids
•
•
•
Solids have a fixed shape and volume.
Solids are crystalline or noncrystalline.
Solids are not compressible - particles are
close together.
• Most solids have a slightly higher density
than their liquid state. Solids sink in their
liquid.
– Ice is an important exception since ice is
actually less dense than water. Ice floats in
water.
• Solids do not mix by diffusion or osmosis.
13.5 Crystalline solids
- Solid arranged
in a specific
order.
- Crystalline
solids have
regular
geometric
shapes /
patterns like
hexagonal
Glucose
Quartz
Cu
Emerald
SOLIDS
Type
Ionic
Particles
metal cations
& nonmetal
anions
nonmetal
Molecular
atoms or
molecules
metal atoms
surrounded
Metallic
by "sea of
electrons"
mp & bp Other properties
High
Low
Varies
hard, brittle,
some soluble in
water,
conduct electricity
when melted or
dissolved in water
usually insoluble in
water, do not conduct
electricity
malleable, ductile,
insoluble in most
liquid solvents,
conduct electricity
Ex.
KCl
AgBr
CaF2
MgCl2
S8
Dry ice
silver
zinc
Salt NaCl
Ice
Copper
13.6 HEATING CURVE
HEATING CURVE
gas
l D g
T (C)
bp
liquid
mp
s D l
solid
Heat Added g g
g
13.7 Structure of Water
H2O has a bent molecular geometry
with a bond angle less than 109.5 
1. Water has very polar O-H bonds: can
dissolve many ionic compounds and mix
with other polar substances
2. Water has strong H bond Forces between
molecules.
13.8 Properties of water
• Very polar, high IMF
• Low vapor pressure
• Unusually High bp & mp: bp=100C,
mp=0C
• High surface tension
• Water expands as it freezes 
Density of ice is less than density of
liquid water ( really rare and odd)
For Fun
• Henry’s Law http://www.youtube.com/watch?v=8yU5ycFXoo&feature=related
• Solubility of a gas in a liquid increases as P
increases, and decreases as P decreases
• When you open soda can, you decrease the
pressure, and some CO2 gas comes out of
solution as bubbles (solubility decreased)
• The Bends http://www.youtube.com/watch?v=0ixYDJAYOYk
Self Test
• Page 382
• Try 1-5, 11-13
• Answers in Appendix J