What’s the MATTER:Classify Changes of Matter

Chemical vs. Physical Changes

Matter, Classify Changes of Matter

At the conclusion of our time together, you should be able to:

1. Characterize various changes of matter2. Recognize that a change of state in

matter is a physical change

Interesting Signs:

Physical

Physical Change

A change in matter from one form to another without changing its chemical properties

the substances are not altered chemically, but are merely changed to another phase (i.e. gas, liquid, solid) or separated or combined. (most can be reversed)No change in identity of the matter.

Physical Change

Examples = Change in state or phase change Dissolving Compressing Light emission/absorption Electrons passing through metals

Physical Change

More Examples =

boiling of a liquid melting of a solid dissolving a solid in a

liquid to give a homogeneous mixture

making a solution

Chemical Change the substances are altered

chemically and display different physical and chemical properties after the change.

Atoms in the reactants are rearranged to form one or more different substances

Old bonds are broken; new bonds form

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Your working TV sits on top of your non-working TV.

A tornado hits your neighborhood and does $100,000 worth of improvements.

Chemical

Chemical Change

Bonds are made / broken Change in oxidation states

Cl-1 Cl-1

21

Li +1

Chemical

Chemical Change

In this case, Li loses one electron to the Cl. It will split the chlorine molecule and form LiCl, lithium chloride.

Cl-1

21

Li +1

Possible Signs of a Chemical Change“Chemists Get Practice Trying Labs”

Color Change Gas Produced

( not from boiling!) Precipitate – a solid formed by

mixing two liquids together Temperature Change Exothermic (hot) or endothermic (cold) LightTypically, more than one indicator will

be seen.

Learning Check

Classify each of the following as a 1) physical change or 2) chemical

changeA. ____ a burning candleB. ____ melting ice

C. ____ toasting a marshmallow D. ____ cutting a pizza E. ____ Tarnished silver

21212

Chemical Reaction

A process in which at least one new substance is produced as a result of chemical change.

In a chemical reaction The way atoms are joined is changed Atoms aren’t created or destroyed. Can be described several ways:

In a sentence Copper reacts with chlorine to form

copper (II) chloride. In a word equation

Copper + chlorine ® copper (II) chloride Formulas

Cu+ Cl2 CuCl2

Examples of Chemical Change

Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.

• Burning hydrogen (H2) in oxygen (O2) gives H2O.

Will This be on the Test????

A Chemical Equation

Reactants Products

Remember the Law of Conservation of Mass

In a physical change or a chemical reaction, mass (and energy) is neither created or destroyed, but can change form.

(Antoine Lavoisier)

Conservation of Mass and Energy

Mass and Energy cannot be created or destroyed, but can change form

Symbols Used In Equations

separates the reactants from products Read as “reacts to form” or “yields”

+ read as “and” or “reacts with” (s) after the formula -solid (g) after the formula -gas (l) after the formula –liquid (aq) after the formula- aqueous solution

Dissolved in water.

More Symbols used in Equations

­ used after a product indicates a gas; same as (g)

¯ used after a product indicates a solid or ppt (precipitate); same as (s)

Even More Symbols used in Equations

indicates a reversible reaction (More later)

shows that heat is supplied to the reaction

is used to indicate a catalyst was supplied, in this case, platinum.

heat , ® ®

Pt ®

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Hittite News:

What Is A Catalyst?

A substance that speeds up a reaction without being changed by the reaction.

Enzymes are biological or protein catalysts.

Diatomic Elements

There are 8 elements that never want to be alone.

If they are not with another element, they form diatomic molecules.

H2 , N2 , O2 , F2 , Cl2 , Br2 , I2 , and At2 @ Brother HON CLIF 1 + 7 pattern on the periodic table

1 + 7 Pattern On The Periodic Table

Matter, Classify Changes of Matter

Let’s see if you can:

1. Characterize various changes of matter2. Recognize that a change of state in

matter is a physical change

Physical vs. Chemical Change

Examples:melting flame produced paper cut dissolving salt

in water tarnishes in air

physicalchemicalphysicalphysical

chemical

Examples: rusting ironmixing mud and

water burning a log freezing water grinding spices

Physical vs. Chemical Change

chemicalphysical

chemicalphysicalphysical

A difference between physical change and chemical change is that

1. chemical change involves energy while physical change does not.

2. physical change involves energy while chemical change does not.

3. different kinds of molecules are present after a physical change but not after a chemical change.

4. different kinds of molecules are present after a chemical change but not after a physical change

In making a pizza, which process involves a chemical change?

1. Mixing spices for the sauce

2. Slicing pepperoni for the topping

3. Spreading cheese on the pizza

4. Baking the dough to form the crust

All You Really Need To Know You Can Learn From Noah's Ark

11. Remember that the ark was built by amateurs; the Titanic was built by professionals.

12. Remember that woodpeckers inside are a larger threat than the storm outside.