Changing Matter 2-3

Objectives

• > Explain physical change, and give examples of physical changes.

• > Explain chemical change, and give examples of chemical changes.

• > Compare and contrast physical and chemical changes.

• > Describe how to detect whether a chemical change has occurred.

Phases of Matter• There are 4 phases of

Matter–Solid, Liquid, Gas, Plasma

–Molecules are always moving. They can vibrate and they can expand.

Molecular movement

• Solids – molecules constantly vibrating

• Liquids- molecules are spreading

• Gases – Molecules are expanding

Phases of MatterMatter can change from form to

form depending on the amount of energy (heat) is available.

Solid to liquid to gas.

Ice in a pan melts then begins to boil and turn to steam.

Phase changes & Temperature

___________ /

/

/

/

/

_________________

Phase changes occur at 1 temperature.

Physical Changes• Physical changes occur

without creating something new. They effect the physical properties of a substance. Such as melting, mixing, or dissolving. If you can change it back it is a physical change.

Chemical changes

• Chemical changes occur when the composition is changed and something different is created.

• You can tell because of odor, bubbles, color changes, sound, heat or light.

• Chemical Change Clip

Chemical changes• Chemical changes can not be

reversed to go back to original state.

• Chemical changes can break down compound such as water to create hydrogen and oxygen.

Phases of matter• Solids- definite shape and volume –Crystalline- orderly arrangement of atoms- diamond

–Amorphous-opposite- gum

Phases Cont’d• Liquid- definite volume no definite shape.–Surface tension-force acting on particles at the surface causing droplets to form.

Phases Cont’dPhases Cont’d

Gas- no definite shape Gas- no definite shape and no definite volume.and no definite volume.

Particles expand and Particles expand and spread out.spread out.

Change in phase/state• Condensation- energy

released when gas changes to a liquid

• Temperature and state do not change together

Energy must be added to separate the particles as ice melts; the same amount of energy is released when water freezes.

Energy is absorbed when water vaporizes; the same amount of energy is released when the water vapor condenses.

EnergyReleased to condense

EnergyabsorbedTo vaporize

–20 0 20 40 60 80 100 120 Relative energy Temperature (˚C)

100

90

80

70

60

50

40

30

20

10

0

Energy Released to Solidify Energy absorbed

to melt

Change in phase/state• Evaporization- energy

required to change liquid to gas

• Sublimation- energy required to change solid to a gas

• States of Matter Clip

Kinetic Theory

• All matter is made of atoms that act like particles

• Particles are always in motion, hotter= faster

Kinetic Theory Cont’d

• At same temperature heavier particles move slower than lighter particles.

Energy

• The ability to change matter and the capacity to do work–Kinetic energy – energy of motion

–Potential energy- energy of position

Energy Cont’d• Temperature- Average kinetic energy.

• Amount of particles do not matter

• High temperature means high kinetic energy

Energy Cont’d

–Thermal energy is the total kinetic energy of particles that make up the object.

–The bigger the object more T.E.

• Conservation of mass and energy– we cannot create or destroy either