Physical and Physical and Chemical Chemical ChangesChanges

77thth Grade Science Grade Science

Physical ChangesPhysical ChangesMatter is always changing form, size, shape,

color, etc. There are 2 types of changes that matter undergoes.

PHYSICAL OR CHEMICAL CHANGEI. 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 Examples of Physical ChangesChanges

- Verbs used to describe physical changes – grind, dissolve, erode, rip, tear, break, phase change (melt, freeze, condense, etc)

Other Physical Change Other Physical Change ExamplesExamples

• PAPER TORN INTO PIECES– SUGAR DISSOLVED INTO TEA– SALT DISSOLVED INTO WATER– NAILS OR HAIR CUT

Chemical ChangesChemical ChangesThe other way that matter can be

changed is call a CHEMICAL CHANGE.

II. CHEMICAL CHANGE – occurs when 2 or more substances are combined into entirely new substance with all new properties. CANNOT CHANGE IT BACK!!!!!

Chemical Change VerbsChemical Change Verbs• Chemical Change Verbs: rusting,

rotting, curdling, burning, cooking, light sensitivity, digesting, tarnishing.

Kinetic Theory of Matter 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

• 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

• MATTER CHANGES FROM ONE STATE OF MATTER TO ANOTHER – WHEN HEAT (ENERGY) IS ADDED– WHEN HEAT (ENERGY IS TAKEN

AWAY

• 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• H2O H2O H2O

Phase Changes are PHYSICAL Phase Changes are PHYSICAL PHYSICAL!!!!!PHYSICAL!!!!!

• Types of Phase Changes:• 1. Melting• 2. Freezing• 3. Evaporation• 4. Boiling• 5. Condensation• 6. Sublimation• 7. Deposition• ALL phase changes are caused by

ADDING or TAKING away energy!!!

MeltingMelting1. 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/VaporizationEvaporation/Vaporization2. 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- ageneral term for any substance changing toa gas.

BoilingBoiling3. 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!!!VAPORIZATION!!!• Remember that vaporization is a

general word for any substance changing to a gas.

• Boiling, evaporation, and sublimation are ALL examples of vaporization!!!

CondensationCondensation4. 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.

FreezingFreezing5) FREEZING5) FREEZING

– CHANGING FROM A LIQUID TO A SOLIDCHANGING FROM A LIQUID TO A SOLID– ENERGY IS REMOVEDENERGY IS REMOVED

• THE PARTICLES MOVE EVEN SLOWERTHE PARTICLES MOVE EVEN SLOWER• THE ATTRACTION BETWEEN THE PARTICLES THE ATTRACTION BETWEEN THE PARTICLES

BEGAN TO PULL THE PARTICLES CLOSER BEGAN TO PULL THE PARTICLES CLOSER TOGETHER & THE MATTER TURNS INTO A TOGETHER & THE MATTER TURNS INTO A SOLIDSOLID

• Increase density.Increase density.•Water freezes at 32 F, 0 C•EX: water to ice, wax or chocolate hardening

SOLIDIFICATION!!!!SOLIDIFICATION!!!!• Solidification is a general word for

any substance changing to a solid.

• Freezing and deposition are examples of SOLIDIFICATION!

SublimationSublimation6) 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.

DepositionDeposition7) 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?

DRAW THIS DIAGRAM IN YOUR DRAW THIS DIAGRAM IN YOUR NOTES!!!!NOTES!!!!

Let’s Sing!!!!Let’s Sing!!!!• 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 ChangesChemical ChangesThe other way that matter can be

changed is call a CHEMICAL CHANGE.

II. CHEMICAL CHANGE – occurs when 2 or more substances are combined into entirely new substance with all new properties. CANNOT CHANGE IT BACK!!!!!

Chemical Change VerbsChemical Change Verbs• Chemical Change Verbs: rusting,

rotting, curdling, burning, cooking, light sensitivity, digesting, tarnishing.

Chemical ChangesChemical 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