Physical and
Chemical
Changes
3rd Quarter 2012
Kinetic Theory of Matter
THEORY OF KINETIC
ENERGY
A. ATOMS ARE ALWAYS
MOVING
B. THE MORE ENERGY ADDED
TO THE ATOMS, THE FASTER
& FARTHER APART THEY
MOVE
Physical Changes
Matter is always changing form, size, shape,
color, etc. There are 2 types of changes
that matter undergoes.
PHYSICAL OR CHEMICAL CHANGE
I. Physical Changes: a change of matter
without changing the identity of the
substance. IN OTHER WORDS
– A CHANGE IN STATE
– A CHANGE IN SIZE, SHAPE, MASS
– DOES NOT CHANGE THE CHEMICAL
MAKE UP OF THE MATTER
– YOU HAVE WHAT YOU STARTED
WITH JUST IN A DIFFERENT FORM
Examples of Physical
Changes
- Verbs used to describe physical
changes – grind, dissolve, erode,
rip, tear, break, phase change
(melt, freeze, condense, etc)
Other Physical Change
Examples
• PAPER TORN INTO PIECES
–SUGAR DISSOLVED INTO TEA
–SALT DISSOLVED INTO WATER
–NAILS OR HAIR CUT
Phase Changes are PHYSICAL
PHYSICAL!!!!!
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Types of Phase Changes:
1. Melting
2. Freezing
3. Evaporization
4. Condensation
5. Sublimation
6. Deposition
ALL phase changes are caused by
ADDING or TAKING away energy!!!
• MATTER CHANGES FROM ONE
STATE OF MATTER TO ANOTHER
–WHEN HEAT (ENERGY) IS ADDED
–WHEN HEAT (ENERGY IS TAKEN
AWAY
DRAW THIS DIAGRAM IN YOUR
NOTES!!!!
• CHANGING STATES DOES NOT
CHANGE THE CHEMICAL MAKE UP
OF THE MATTER
• YOU HAVE WHAT YOU STARTED
WITH JUST IN A DIFFERENT
FORM
• ICE  WATER  WATER VAPOR
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H 2O
H 2O
H 2O
• WHEN MOLECULES MOVE FASTER, THEY
PRODUCE MORE FRICTION AND THEREFORE
MORE HEAT. THEY SPREAD FARTHER APART
& EXPAND
• WHEN MOLECULES MOVE SLOWER, THEY
CAUSE LESS FRICTION AND THEREFORE
LESS HEAT & CLOSER TOGETHER &
CONTRACT
Melting
1. MELTING – matter changing FROM A
SOLID TO A LIQUID.
– Energy is added
– When more heat (energy) is added
to matter the particles move faster
till the bonds break.
– Decrease density except ice to
water.
Evaporation/Vaporization
2. EVAPORATION
– Matter changing FROM A LIQUID TO
A GAS AT THE SURFACE
– ENERGY IS ADDED TO SURFACE OF
LIQUID
– THE PARTICLES AT THE SURFACE
MOVE FASTER breaking bonds.
– Decreases density.
• VAPORIZATION- a
general term for any
substance changing to
a gas.
Boiling
3. BOILING
– matter changing FROM A LIQUID TO A GAS
ALL THROUGHOUT THE LIQUID
– ENERGY IS ADDED TO ALL OF LIQUID
– PARTICLES MOVE FASTER ALL THROUGH THE
LIQUID
– SOME PARTICLES MOVE FAST ENOUGH TO
CHANGE TO GAS WHILE THEY ARE IN THE
MIDDLE OF THE LIQUID
– DENSITY DESCREASES
– Water boils at 212 F, 100C.
• EX: pan of liquid on the stove
• VAPORIZATION- a general term
for any substance changing to a gas.
VAPORIZATION!!!
• Remember that vaporization is a
general word for any substance
changing to a gas.
• Boiling, evaporation, and sublimation
are ALL examples of vaporization!!!
Condensation
4. CONDENSATION
– Matter CHANGING FROM A GAS TO A LIQUID
– ENERGY IS REMOVED
• THE PARTICLES MOVE SLOWER
• THE ATTRACTION BETWEEN THE PARTICLES BEGAN
TO PULL THE PARTICLES CLOSER TOGETHER & THE
MATTER TURNS INTO A LIQUID
• DENSTITY INCREASES
• Ex: dew in the lawn, water running down mirror, ring on table
under glass.
• FREEZING
Freezing
– CHANGING FROM A LIQUID TO A SOLID
– ENERGY IS REMOVED
• THE PARTICLES MOVE EVEN SLOWER
• THE ATTRACTION BETWEEN THE PARTICLES
BEGAN TO PULL THE PARTICLES CLOSER
TOGETHER & THE MATTER TURNS INTO A
SOLID
• Increase density.
• Water freezes at 32 F, 0 C
• EX: water to ice, wax or chocolate hardening
SOLIDIFICATION!!!!
• Solidification is a general word for
any substance changing to a solid.
• Freezing and deposition are
examples of SOLIDIFICATION!
Sublimation
• 5. Sublimation: matter changes straight
from a solid to a gas!!!!
• Heat added rapidly
• Molecules speed up and spread out rapidly
• decrease density
• Examples of Sublimation:
dry ice, shrinking ice in a
freezer, air freshener.
Deposition
-Deposition- when matter changes
from a gas directly to a solid.
-Heat is taken away rapidly
-Density increases
-Molecules slow down and get closer
together.
Examples:
Snowflakes,
frost on a wind shield
• WHAT HAS TO HAPPEN FOR
THESE CHANGES OF STATES TO
OCCUR?
Bellringer 2:
1. All phase changes are:
a. physical properties
b. physical changes
c. Chemical properties
d. chemical changes
2. Condensation is:
a. Liquid to gas
b. Gas to solid
c. Solid to gas
d. gas to liquid
Let’s Sing!!!!
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Phase changes are physical, physical…
Melting is physical…. Freezing is physical.
BOYS: Let me see some condensation.
GIRLS: (in high pitch voice) It’s physical.
BOYS: Let me see some sublimation.
GIRLS: (in high pitch voice) It’s physical.
Phase changes are physical, physical…
Boiling is physical… Boiling is physical…
BOYS: Let me see some deposition.
GIRLS: (in high pitch voice) It’s physical
BOYS: Let me see some evaporation.
GIRLS: (in high pitch voice) It’s physical
Chemical Changes
The other way that matter can be
changed is call a CHEMICAL
CHANGE.
occurs
when 2 or more substances
are combined into entirely
new substance with all new
properties. CANNOT
CHANGE IT BACK!!!!!
II. CHEMICAL CHANGE –
Chemical Change Verbs
• Chemical Change Verbs: rusting,
rotting, curdling, burning, cooking,
light sensitivity, digesting,
tarnishing.
Chemical Changes
– SOME SIGNS OF A CHEMICAL CHANGE
• FIZZES OR BUBBLES
• COLOR CHANGE
• HEAT GIVEN OFF
• LIGHT GIVEN OFF
• ODOR
• HEAT REQUIRED FOR REACTION
• NEW SUBSTANCE FORMED
– Precipitate (solid)
– Precipitate (gas bubbles)
• CHEMICAL CHANGE EXAMPLES
–BAKING BREAD – NO LONGER
HAVE FLOUR, EGGS, MILK,
YEAST
–ALKASELTER
–BAKING SODA & VINEGAR
–RUST
–TARNISH