1. Some Properties of a Liquid
Surface Tension: The resistance to an increase in its surface area (polar molecules, liquid metals).
Strong intermolecular forces
High surface tension =

2. IAN BUG
Surface of water behaving
like it had an “elastic skin”

3. attracted to each other
Capillary Action: Spontaneous rising of a liquid in a narrow tube.
Cohesion is the intermolecular attraction between like molecules
Adhesion
Cohesion
Adhesion is an attraction between unlike molecules
attracted to glass
attracted to each other

4. Some Properties of a Liquid
Viscosity: Resistance to flow
High viscosity is an indication of strong intermolecular forces

5. General Classification of Solids
Crystalline Solids: Well-ordered, definite arrangement of atoms. (Examples- metals, H2O, diamond)
Amorphous: No pattern to the arrangement of particles. (Examples- glass, plastic, wax)

6. Representation of Components in a Crystalline Solid
Lattice: A 3-dimensional system of points designating the centers of components (atoms, ions, or molecules) that make up the substance.

7. Which of the following consistently have the highest melting points?
Metals
Salts
Molecular crystals
Alkanes
Hydrogen-bonded compounds.
Answer: B

8. How sharp are you? Gases can be compressed more easily than liquids
because:
Gas molecules are smaller than liquid molecules
B. The kinetic energy of gas molecules is higher than that
found in liquids
The average intermolecular distances are greater in gases
than those found in liquids.
Intermolecular forces increase as gas moleculues are brought
closer together.
E. None of the above.
Answer: C In a gas, the molecules are separated by a large distance
and are able to be compressed by increasing the pressure. They move
independently of one another because there is no appreciable intermolecular
interactions among them.

9. In which of the following are the intermolecular
forces listed from the weakest to the strongest?
Dipole-dipole>London>hydrogen bonds
London<dipole-dipole<hydrogen bonds
Hydrogen bonds<dipole-dipole<London
London>hydrogen bonds>dipole-dipole
London>Akbar bonds>dipole-dipole>Basu forces
Answer: B

10. Which of the following compounds will NOT hydrogen- bond>?
CF4
CH3OH
H2NCH2CH2CH3
HOCH2CH2OH
HClO
Answer: A

11. Water has a higher capillary action than mercury due to:
Higher dipole-dipole forces between the water molecules
Strong cohesive forces within water.
Very significant induced intermolecular attractions.
Weak adhesive forces in water
Strong cohesive forces in water which work with strong
adhesive forces.
Answer: E. The strong adhesive forces leads to a creeping effect
as water moves up the narrow tubing and the strong cohesive forces
attempt to minimize the surface area.

12. Small drops of water tend to bead up because of:
High capillary action
the shape of the meniscus
The resistance to increased surface area.
Low London dispersion forces
Weak covalent bonds.
Answer: C. This is a description of surface tension, which is a
result of high dipole-dipole forces between water molecules. These
intermolecular forces are also called…..hydrogen bonds!

13. Several liquids are compared by adding them to a series
of 50 mL graduated cylinders, then dropping a steel
ball of uniform size and mass into each. The time
required for the ball to reach the bottom of the cylinder
is noted. This is a method used to compare the
differences in a property of liquids known as:
Surface tension
Buoyancy
Capillary action
Viscosity
Surface contraction
Answer: D. The resistance to flow of any fluid is called viscosity. As
You would predict, liquids with high viscosity (ex: maple syrup) have
large intermolecular forces.

14. Types of Crystalline Solids
There are four types of crystalline solid:
- Molecular (formed from atoms or molecules) - usually soft with low melting points and poor conductivity.
- Covalent network (formed from atoms) - very hard with very high melting points and poor conductivity.
- Ionic (formed form ions) - hard, brittle, high melting points and poor conductivity.
- Metallic (formed from metal atoms) - soft or hard, high melting points, good conductivity, malleable and ductile.

15. Bonding in Crystalline Solids
Know these!!
Metallic bonds are formed from metal nuclei floating in a sea of electrons.

16. Crystalline Solids
Molecular
Covalent Network
Ionic
Metallic

17. Metal Alloys
Substitutional Alloy: some metal atoms replaced by others of similar size.
brass = Cu/Zn

18. Metal Alloys (continued)
Interstitial Alloy: Interstices (holes) in closest packed metal structure are occupied by small atoms.
steel = iron + carbon

19. Please complete the following problems:
Pg #12, 20, 30, 32, 34, 36 (a,b and d) and 110

20. Phase Changes & Energy
Endothermic: melting, evaporating/boiling & sublimation
Exothermic: freezing, condensation, & deposition

21. Phase Changes & Energy
heat of vaporization: the heat energy required to evaporate a given mass of liquid at a constant temperature
heat of fusion: the heat energy required to melt a given mass of solid at a constant temperature
The temperature, (average KE), during a phase change (such as boiling) does not change!
Any heat added during boiling gives more molecules enough energy to escape the liquid.
Heating Curve

22. Phase Changes & Energy
Generally, it will take more heat to vaporize a liquid than to melt a solid… (∆H(vap) > ∆H(fusion) ) Why?
Every intermolecular bond is broken when vaporizing, but only some of the intermolecular forces break when melting solids. ?

23. Practice Time:
Please attempt the following problems
(at your workstations!):
pg : 88 and 90.
To be collected by end of block.
OR?

24. Do Now: Please pick up a copy of today’s assignment and complete it INDEPENDENTLY!
Objective: Describe vapor pressurechanges in state,
and phase diagrams.
HW: Complete problem set handout.
120516

25. Gases can be liquefied by: increasing pressure at some temperature.
Liquefying Gases
Gases can be liquefied by:
increasing pressure at some temperature.
decreasing the temperature at some pressure.
- Critical temperature: the highest temperature at which a substance can remain a liquid regardless of the pressure applied.
- Critical pressure: the pressure needed at the critical temperature.

26. Phase Diagrams
Shows the relationship between the 3 phases of matter at various temperatures and pressures.
Triple Point: All 3 phases of matter at equilibrium.
Critical Point: The highest temperature at which the liquid phase can exist.

27. Phase Diagrams of H2O and CO2
Notice the slope of the solid–liquid equilibrium line.