Appetizer – 1/14/13

1. Appetizer – 1/14/13 What phase change occurs when a solid changes directly into a gas? • Freezing • Melting • Evaporation • sublimation

2. Review • Compare/Contrast: elements, mixtures, compounds • “Meet the Elements” They Might Be Giants - Meet the Elements

3. Chapter 16 Solids, Liquids, and Gases

4. States of Matter The Kinetic Theory • All matter is composed of small particles (atoms, molecules, and ions) • These particles are constantly moving • The moving particles collide with each other and with the walls of their container

6. Thermal Energy • Thermal energy = kinetic energy in particles • Cold particles move slower • Hot particles move faster The Phantom's Portrait Parlor: Phases of Matter Observe water molecules at different temperatures. Write your observations in the space provided on your notes.

7. Solids • The particles of a solid are closely packed together they have a constant shape and volume • The particles vibrate in place but do not move around • Particles of solids have low kinetic energy • Most solids have particles in specific geometric arrangement

8. Liquids • The melting point of a substance is the temperature that a solid begins to liquefy • At the melting point, particles have enough kinetic energy to break the bonds that keep them in the solid state • Particles in liquid move more freely than particles of solids • Liquids take the shape of their container but have a constant volume

10. Gases • Liquids become gases in a process called vaporization: • Boiling • evaporation • In gases, the particles are far apart. They have enough kinetic energy to break molecular bonds and spread apart. • Gases have NO definite shape OR volume. • Diffusion is when gas particles spread out

11. Boiling • Particles in a liquid are pushed down by external pressure. • When a liquid is heated to its boiling point, the pressure of the vapor pushing up becomes greater than the external pressure letting the particles escape

12. When copper reacts with oxygen in the air, a color change occurs, and the metal changes color from reddish brown to green. This green color is called a patina, and it has a different chemical composition from copper. What type of change occurs to produce a patina? • Dissolving • Conductivity • Physical change • Chemical change

14. Plasma • Plasma is matter consisting of positive and negatively charged particles • Occurs when gases get so hot that collisions cause electrons to be stripped off • Found in the sun, neon lights, and lightning bolts

15. Thermal Expansion • Thermal expansion is the increase in the size of a substance when the temperature increases • When temperature decreases, particles slow down and the attraction between particles increases • When temperature increases, particles speedup and the attraction between particles is reduced

16. Thermal Expansion • Thermometers show thermal expansion in liquids • Hot air balloons show thermal expansion in gases

17. Water is weirder… • What happens if you put an unopened drink in the freezer for too long? • Almost every substance shrinks when it’s cold and grows when it’s warm – except water • The type of crystal structure that ice forms has more empty spaces than liquid water so ice is larger and less dense than liquid water

18. Why does ice float?

19. Solid or Liquid? • Amorphous solids do not have the same ordered structure as crystal solids • Examples: glass, and plastic (silly putty) • Liquid crystals do not lose their orderly shape completely when they melt. They are highly responsive to temperature and electric fields • Examples: calculators, cell phone screens & LCD tvs