Transcript Ch. 2.3 Notes

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 Matter
Matter 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 atomsdiamond
–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’d
Gas- no definite shape
and no definite volume.
Particles expand and
spread out.
Change in phase/state
• Condensation- energy
released when gas changes
to a liquid
• Temperature and state do
not change together
100
Energy must be added
90 to separate the
particles as ice melts;
80
the same amount of
70 energy is released
when water freezes.
Energy is absorbed
when water vaporizes;
the same amount of
energy is released
when the water vapor
condenses.
60
50
Energy
Released to
condense
40
Energy
absorbed
To vaporize
30
20
Energy
10 Released to
Energy absorbed
Solidify
0
–20
0 to melt 20
40
Relative energy
60
80
Temperature (˚C)
100
120
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