1. States of Matter
Unit 7

2. Overview States and Properties of Matter Kinetic Molecular Theory
Phase Changes
Diagrams
Phase Diagrams
Heating/Cooling Curves
Heat of Fusion/Vaporization
Vapor Pressure

3. States of Matter Based upon particle arrangement
Based upon energy of particles
Based upon distance between particles

4. 3 States of Matter
SOLIDS — have rigid shape, fixed volume; external shape can reflect the atomic and molecular arrangement
Reasonably well understood
LIQUIDS — have no fixed shape and may not fill a container completely
Not well understood
GASES — expand to fill their container
Good theoretical understanding

5. Solids Definite shape & definite volume Not easily compressible
Particles of solids are tightly packed, vibrating about a fixed position.
Not easily compressible
Little free space between particles
Do not flow easily
Particles cannot move/slide past one another
Infinite number of free surfaces

6. Solids (Types)
Crystalline Solids: highly regular arrangement of their components
Amorphous solids: considerable disorder in their structures (glass, plastic).

7. Allotropes
Some chemical elements can exist in two or more different forms. Atoms of the element bond together differently.
Diamond, carbon atoms bond together in a tetrahedral lattice
Graphite, carbon atoms bond together in sheets

8. Liquids Indefinite shape but definite volume Not easily compressible
Particles are tightly packed, but are far enough apart to slide over one another.
Not easily compressible
Little free space between particles
Liquids flow easily
Particles can move/slide past one another
Have one free surface

9. Surface Tension
Intermolecular cohesive attraction causing liquid to minimize its surface area
Mostly in polar molecules and liquid metals

10. Illustration of capillary action for large and small bore capillaries.
Attraction of the surface of a liquid to the surface of a solid, which causes the liquid to rise in a tube
Illustration of capillary action for large and small bore capillaries.

11. Glycerine, also called glycerol, is a liquid with a high viscosity
Liquids are fluids – they FLOW. Viscosity is the resistance to flow.
Example: Syrup has a higher viscosity than water.
Glycerine, also called glycerol, is a liquid with a high viscosity
High viscosity = strong intermolecular forces

12. Viscosity decreases as temperature increases.

13. Gases Indefinite shape and indefinite volume Easily compressible
Particles are very far apart and move freely
Easily compressible
There is a great deal of free space between particles
Flow very easily
Particles randomly move past one another
Gases have no free surfaces

14. Plasma
Sir William Crookes, an English physicist, identified a fourth state of matter, now called plasma
Plasma is by far the most common form of matter
Plasma in the stars and in the tenuous space between them makes up over 99% of the visible universe and perhaps most of that which is not visible

15. Plasma An ionized gas Very good conductor of electricity
Composed of ions
Affected by magnetic fields
Indefinite shape and indefinite volume
Particles can move past one another.
Easily compressible
Great deal of free space between particles.

16. Computer chips and integrated circuits Computer hard drives
Products manufactured using plasmas impact our daily lives:
Computer chips and integrated circuits
Computer hard drives
Electronics
Machine tools
Medical implants and prosthetics
Audio and video tapes
Aircraft and automobile engine parts
Printing on plastic food containers
Energy-efficient window coatings
High-efficiency window coatings
Safe drinking water
Voice and data communications components
Anti-scratch and anti-glare coatings on eyeglasses and other optics

17. Kinetic Molecular Theory1.
pertaining to motion. 2.
caused by motion. 3.
characterized by movement: Running and dancing are kinetic activities.
Origin: 1850–55; < Gk kīnētikós moving, equiv. to kīnē- (verbid s. of kīneîn to move) + -tikos
Source: Websters Dictionary

18. Kinetic Molecular Theory
Atoms and molecules are constantly in motion.
SOLIDS — little movement between particles
LIQUIDS — more space between them than a solid does, but less than a gas
GASES — molecules are moving in random patterns with varying amounts of distance between the particles

19. Changes of State
Changing states requires a change in the energy of a system. Changing states may also be due to the change in pressure in a system.

20. Changes of State

21. Phase Diagrams

22. Phase Diagrams
(T) Triple Point: temperature and pressure at which all three phases exist simultaneously in equilibrium
(C) Critical Point: temperature and pressure beyond which the liquid and solid phase is distinguishable (supercritical liquid)
molecules of a substance have too much kinetic energy to stick together
(page 453 of book = supercritical fluid)

23. Phase Diagrams

24. Water

25. Carbon dioxide

26. Carbon

27. Heat of Fusion (formation)
Energy that must be put into a solid to melt it
Needed to overcome forces holding it together
Heat of fusion given off when liquid freezes
Intermolecular forces within solid more stable and have lower energy than forces within liquid so energy is released during freezing

28. Heat of Vaporization
Energy that must be put into a liquid to turn it into a gas
Energy needed to overcome forces holding liquid together
Heat of vaporization given off when gas condenses
Intermolecular forces become stronger when gas condenses so as gas becomes liquid (more stable), energy is released
Heat of vaporization larger than heat of fusion
Many more intermolecular forces must be overcome in vaporization than melting
(intermolecular forces severed in vaporization but many carry over between solids and liquids)

29. Heating/Cooling Curves
As heat added to a substance in equilibrium, temperature of substance can increase or the substance can change phases, but both changes cannot occur simultaneously
Horizontal line at melting point is heat of fusion
Horizontal line at boiling point is heat of vaporization

30. Heating/Cooling Curves

31. Vapor Pressure
The pressure exerted by molecules as they escape the surface of a liquid and become a gas
As temperature increases, vapor pressure of a liquid increases
When vapor pressure of liquid increases to point where equal with the surrounding atmospheric pressure, the liquid boils
The weaker the intermolecular forces, the easier it is for molecules to escape the surface and turn to gas
Weaker intermolecular forces = higher vapor pressure

32. Vapor Pressure - Equilibrium
As number of gas molecules increases, higher probability that gas molecule will hit surface of liquid and be recaptured
When there is even exchange of liquid and gas molecules, vapor pressure becomes constant (dynamic equilibrium)
Appears that nothing is happening in the system
Vapor pressure of a liquid is the pressure exerted by its vapor when the liquid and vapor states are in equilibrium
When liquid/solid phase is in equilibrium with the gas phase, the pressure of the gas equals the vapor pressure of the substance