What happens to substances when they change states of mater? 3-2: Changes of State What happens to substances when they change states of mater?

Anticipatory Set What happens to a puddle of water on a sunny day? What happens to ice on a warm day? What happens to a pond in very cold temperatures?

California Standards Science Standard 8.3.d: Students know the states of mater depend on molecular motion. Science Standard 8.5.d: Students know physical processes include freezing and boiling, in which a material changes form with no chemical reaction.

Input melting: change in state from solid to liquid. melting point: a characteristic temperature where melting occurs. freezing: change from a liquid to a solid. vaporization: change from a liquid to a gas. evaporation: vaporization that takes place only on the surface of a liquid.

Input boiling: occurs when a liquid changes to a gas below and at the surface. boiling point: the temperature at which a liquid boils. condensation: the change in state from a gas to a liquid. sublimation: occurs when the surface particles of solid gain enough energy that they form a gas.

Input Melting Solid to Liquid Let’s act like a solid! When a substance melts, the particles in the solid vibrate so fast that they break free from their fixed positions (increase). A change from solid to liquid involves a gain in thermal energy. Let’s act like a solid!

Input Freezing Liquid to Solid Let’s act like a solid! When a substance freezes, the particles in the liquid move so slowly that they begin to take on fixed positions (decrease). The change from liquid to solid involves a loss in thermal energy. Let’s act like a solid!

Input Vaporization Liquid to Gas Vaporization that takes place only on the surface of a liquid is called evaporation.

Input Boiling Liquid to Gas The boiling point of a substance depends on the pressure of the air above it. The lower the pressure, the less energy needed for the particles of the liquid to escape into the air. Boiling point is a characteristic property of a substance.

Input Condensation Gas to Liquid During condensation, the particles in a gas lose enough thermal energy to form a liquid. Condensation is the reverse of vaporization. Clouds in the atmosphere form due to condensation.

Input Sublimation Solid to Gas Dry ice, or solid carbon dioxide, is an example of compound that does not turn to liquid at normal atmospheric pressures.

Modeling Temperature and Changes of State A beaker of ice at –10ºC was slowly heated to 110ºC. The graph shows how the temperature of the water changed over time.

Modeling Temperature and Changes of State Reading Graphs: What two variables are plotted on the graph? Temperature (ºC) on the y- axis, time (minutes) on the x-axis

Modeling Temperature and Changes of State Reading Graphs: What is happening to the temperature of the water during segment C of the graph? The temperature is rising from 0ºC to 100ºC.

Modeling Temperature and Changes of State Interpreting Data: What does the temperature value for segment B represent? For segment D? Segment B: melting point of ice; segment D: boiling point of water

Modeling Temperature and Changes of State Drawing Conclusions: What change of state is occurring during segment B of the graph? During segment D? Change from solid to liquid; change from liquid to gas

Check for Understanding Draw a picture of melting. Draw a picture of freezing. Draw a picture of sublimation.

Guided Practice Independent Practice Answer #1, 2, 6 Finish the worksheet. Gain, increase Loss, decrease 6. Boiling point

HOMEWORK EXTENSION Write a detailed SUMMARY of the section and complete the UNANSWERED QUESTIONS section of your notes. Choose two of the remaining Depth & Complexity ICONS in your notes and explain how they relate to this section.