Solids Liquids Gases PHASES OF MATTER Imagine you are the teacher and you have to arrange the students in a way that represents the three different phases of matter. How would you arrange them to represent a solid? What about a liquid? A gas? Solids Liquids Gases

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http://www.youtube.com/watch?v=2Mex61BZQNQ

Why are they so cold?

Why is this snowman melting???

Why is the water evaporating?

What two phases do you see? SOLID What causes this change? LIQUID

A phase change is caused by…… a transfer of energy (heat).

What could cause one phase to change to another? When you add or remove energy from a phase of matter, it changes to another phase Increases in energy will cause: Solid to liquid Liquid to gas 9

Decreases in energy will cause: Gas to liquid Liquid to solid 10

G A S LIQUID SOLID VAPORIZATION CONDENSATION DEPOSITION SUBLIMATION FREEZING MELTING SOLID

HEATING CURVE OF WATER

ENERGY

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Types of energy transfer

http://www.youtube.com/watch?v=BFHjqbXyQxw

CONDUCTION Energy transfer by direct molecular contact Most common through a solid object Can occur when a solid object TOUCHES the molecules of another solid, liquid (Metal bar in water) or gas

Energy is transferred from hot (high kinetic) to cold (high potential) substances Rate of transfer is greatest with a larger difference in temperatures

Convection Transfer of heat through fluids (liquids, gases and magma) Results from differences in density within the fluids

Convection in Liquids Convection in Liquids

The differences in density could be caused by changes in both temperature and/or pressure

Convection in Gases Convection in Gases

Ex: warm air rises, cool air sinks Creates a CONVECTION CELL

Radiation

All objects emit radiant energy (heat) Our Sun emits ALL forms of radiation

When the sun is out….what form of energy do you see???? Maximum Energy from the Sun is in the form of Visible Light (Short waves)

….what form of energy do you feel???? Maximum Energy RE-RADIATED from the Earth is in the form of Infrared (longer waves)

What color should you not wear on a hot and sunny day? Black and rough absorbs the best If it is a good absorber….it is a good radiator (re-radiation)

White (shiny) and smooth is the best reflector

Why does the inside of your car get so hot during the summer?

What is the Greenhouse Effect?

Longer, re-radiated waves are trapped inside

Gases in the atmosphere (carbon dioxide and water vapor) trap energy from the sun. Why would sea level rise if the atmosphere gets too hot?

Without these gases, heat would escape back into space and Earth’s average temperature would be colder.