Physical and Chemical Changes Spring 2009. Kinetic Theory of Matter THEORY OF KINETIC ENERGY A. ATOMS ARE ALWAYS MOVING B. THE MORE ENERGY ADDED TO THE.

Physical and Physical and Chemical Chemical ChangesChanges

Spring 2009Spring 2009

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

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 matter. 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

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

• Types of Phase Changes:• 1. Melting• 2. Freezing• 3. Vaporization• 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

• 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

• 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

MeltingMelting1. MELTING – GOING 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

– GOING 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.

BoilingBoiling3. BOILING

– GOING 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

CondensationCondensation4. CONDENSATION

– 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

FreezingFreezing• FREEZINGFREEZING

– 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 THE ATTRACTION BETWEEN THE

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

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

hardening

SublimationSublimation• 5. Sublimation: Substance goes straight• from a solid to a gas DRY ICE!!!!• Heat added rapidly• Molecules speed up and spread out• decrease density• Examples of Sublimation: dry ice, shrinking ice in a freezer

DepositionDeposition-Deposition is when a substance

changes from gas to 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 HAPPEN?

Chemical PropertiesChemical PropertiesII. Chemical Properties: properties

describes the ability of an object to change into a new substance. (flammability, reactivity)

Chemical Change verbs: rusting, rotting, curdling, burning, cooking, light sensitivity, digesting, tarnishing.

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 ChangesChemical Changes• CHEMICAL CHANGE

– OR BROKEN DOWN INTO A DIFFERENT SUBSTANCE– 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)– Gas (bubbles)

• CHEMICAL CHANGE EXAMPLES– BAKING BREAD – NO LONGER

HAVE FLOUR, EGGS, MILK, YEAST

– ALKASELTER– BAKING SODA & VINEGAR– RUST– TARNISH