States of Matter
How does thermal energy affect the
state of a substance?
• Thermal Energy interactive Video –
Investigate at home
• Video molecules in motion
Temperature
• Temperature is the average kinetic energy of
the atoms/molecules in a system.
• Temp. measures how “hot” something is.
Temperature Scales
• Fahrenheit (English system)
– Water freezes at 32⁰ F and boils at 212⁰ F.
• Celsius
– freezing point of water is 0⁰ C, and boiling point is
100⁰ C.
• Kelvin (scale that is based on energy content)
– At zero Kelvin (absolute zero) all molecular motion
stops.
– Scientists have figured out a way to get a
temperature only a few billionths of a degree
above absolute zero.
4 States of Matter
• Matter can move from one phase to
another.
• When temp. goes up, matter becomes
more excited and active.
• As the temperature rises, matter moves to
a more active state.
4 States/Phases of Matter
•
•
•
•
Solids
Liquids
Gases
Plasmas
What is a solid?
• Solids have a
– definite shape
– definite volume.
– Molecules are tightly packed
– Cannot move freely, can only vibrate
– Energy and temp. are very low
Solids are broadly
characterized as
• Crystalline Solids- Repeating pattern
Examples
Ghost crystals
Salt
Copper Sulfate
crystals in rocks
rock candy
• Amorphous Solids- - Non-repeating
pattern
Examples
Wax
hand putty
Gum
play dough
peanut butter
clay
What is a liquid?
Liquids have
• no definite shape (take shape of container
in which it is held)
• Definite volume.
• Molecules are closely packed, but move
more than in a solid
• Energy and temp. are higher than in solids
What is a Gas?
• Have indefinite and unstable shape
• No definite volume, volume determined by
container
• Molecules are far apart and have lots of freedom of
movement.
• Energy and temperature are higher than those of
both solids and liquids.
• Gases diffuse (move from higher concentrations to
lower)
– Heat will increase the rate of diffusion.
What is plasma?
• Ionized Gas-- a cloud of
protons, neutrons and
electrons where all the
electrons have come loose
from the atoms
• This is an extreme gas!
Strikes the other atoms so
forcefully it knocks off an
electron!
• Particles are very far apart
and moving like CRAZY!
• Super-heated, superexcited!
Neon
Signs
Plasma Examples
Our Sun,
the core
of stars
Lightning
Plasma TV
Aurora
Borealis
plasma balls
Plasma Cutters
A Phase Change
• A "phase" describes a physical state
of matter.
– If energy is added (like increasing the
temperature) or if energy is taken away
(like freezing something), you have
created a physical change.
A Phase Change
• A compound or element can move from one phase
to another, but still be the same substance.
• It may require extreme temperatures or extreme
pressures, but it can be done.
Melting
SOLID  LIQUID
• Melting Point - the temperature at
which matter changes from solid to
liquid, (e.g. The melting point of
water from ice to liquid water is 0 °C)
Evaporation
LIQUID  GAS
• Boiling a liquid to form a gas is called
vaporization.
Super Heated Steam Video
https://www.youtube.com/watch?v=yFnNK9fNdls
Evaporation
How does evaporation differ
from vaporization?
Vaporization, Boiling,
Evaporation
Boiling vs. Evaporation
Sublimation
SOLID  GAS
Examples:
Mothballs in closet
Dry ice
Condensation
GAS  LIQUID
Examples:
Glass of ice water
Bathroom mirror
after shower
Dew on grass.
Freezing or Solidification
LIQUID  SOLID
Water is the only known substance that expands as
it freezes. Most substances contract.
Deposition
GAS  SOLID
Examples:
Frost on glass- Water
vapor becoming a solid
Pressure and Phase Change
• If lowering the temperature won’t get
a liquid to change to a solid just apply
pressure.
• By applying pressure you are
“pushing” the molecules together.
Thermal Expansion
• Thermal expansion is the tendency of a
matter to change in volume in response
to a change in temperature.
Examples:
Sidewalk cracking
Bridges
Demo – Hand Boiler
Heating and Cooling Curves
• Heating Curve Link