1/11/12 A/B DayLEQ: What is the difference between a physical and chemical change and how can we tell when they happen?

1. What is the difference between a mixture and a solution? 2. In a glass of chocolate milk, what is the solvent and what is the solute?3. What does solubility measure?4. A scientist needs to use a material that will not get very hot. Should the scientist use something with a HIGH specific heat or a low specific heat?5. EXPLAIN your answer to #4!

Let’s Review:

If each of these materials is exposed to the same amount of heat, which one will be the

COOLEST?

HOT Q: If 5 grams of gold melts at 200° C, what temperature will cause 50 grams of gold to melt?

HOT Q: Which pure substance is composed of more that one element?

a.Carbonb.Goldc.Waterd.Sodium

Let’s Review!NONMETALS

METALS

METALLOIDS

Help a Scientist pick the right element:1. A metal2. A nonmetal3. A metalloid4. Something malleable5. Something ductile6. Something that is magnetic7. Something that will conduct heat8. Something that will block heat9. Something that is a semiconductor

FIND THAT ELEMENT!1. GROUP 1, PERIOD 1 = 2. GROUP 6, PERIOD 7 = 3. GROUP 2, PERIOD 5 = 4. GROUP 9, PERIOD 4 = 5. GROUP 17, PERIOD 3 = 6. GROUP 11, PERIOD 4 =

EOG Question:

How can a scientist, using the periodic table, find an element with properties similar to another element?

a) by comparing densityb) by finding its periodic groupc) by comparing malleabilityd) by comparing atomic weight

Chemical Weathering

Mechanical Weathering

CHEMICAL WEATHERING:

• Chemicals break down rock by chemically changing the rock

• Usually indicated by color change!

• Example: Acid Rain, rust

MECHANICAL WEATHERING:

• Physical changes to rock (rocks break into smaller pieces)

• Example: ice, salt, wind, and water break down rocks

Today’s LEQ: What is the difference between a physical and chemical change and how can we tell when they happen?

By the end of today, you should be able to…

1. Describe the difference between an physical and chemical change.

2. Use observable evidence to decide if a change is chemical or physical

FOCUS VOCABULARY:

87. Chemical Change88. Physical Change

ACTIVATOR: Draw this in your notes

Record 3-5 observations you have about the paper

How does the paper look different?

What changed about the paper?

What happened to the paper?

Record 3-5 observations you have about the paper

How does the paper look different?

What changed about the paper?

What happened to the paper?

Demo: Tearing Paper, Burning Paper

How are the two demos different?

Changing Substances

Physical Change:

Ex.

Chemical Change:

Ex.

Evidence:1.2.3.4.

Evidence:1.2.3.4.

Draw this in your notes:

Changing Substances

Physical Change: changes the physical traits of a substance, NOT the identity of the substance

Ex. TEARING PAPER!

Physical Change: Tearing paper

Paper

Same Paper (different size)

Draw this in your notes:

Changing Substances

Physical Change: changes the physical traits of a substance, NOT the identity of the substance

Ex. tearing paper

Chemical Change:substance is changed into a new substance (changes the identity of something)

Ex. Burning Paper!

Chemical Change: Burning paper

Paper

Burnt Paper is a DIFFERENT

SUBSTANCE!

BrainPop: Changing Properties

Changing Substances

Physical Change:

Ex.

Chemical Change:

Ex.

Evidence:1.2.3.4.

Evidence:1.2.3.4.

Instructions:I give you: 8 different types of evidence that happen during physical and chemical changes

You: use your brain to decide which of the things is evidence of physical change and which of the things is evidence of chemical change

Physical Chemical

-Changes color-Melting, freezing, or boiling-Burst of heat-Change in mass or volume-Smoke forms-Change in shape-Usually reversible-Usually irreversible

EVID

ENCE

Physical Change: Chemical Change:

Evidence: Evidence:1. Melting, freezing, or boiling

2. Change in mass or volume

3. Change in shape

4. Usually reversible

1. Changes color

2. Burst of heat

3. Smoke forms

4. Usually irreversible

What evidence can we use to tell this is a physical change?

Paper

Same Paper (different size)

What evidence can we use to tell this is a chemical change?

Paper

Burnt Paper is a DIFFERENT

SUBSTANCE!

Physical Change: Ice melting

Ice = HO

Melted Ice = HO

Chemical Change: Making Water

One OxygenAtom

Two Hydrogen

Atoms

+

Water

Chemical or

Physical?

Melting Ice

Burning Wood

Chopping Wood

Digesting an apple

Breaking Glass

Melting Iron

Bicycle rusting

Melting Ice Cream on a hot day

Cooking a steak

Mixing Peas and Carrots

Rotting Banana

Draw this in your notes:

SORT THESE!!

Burning

wood

Sharpening a pencil

Melting butter

Stretching

copper into

copper wire

A banana rotting

Hammering aluminum

into foil

A nail rusting

Freezing

Kool Aid Boiling water

HOT Q: How do physical and chemical changes relate to the

different ways that the surface of the earth changes over time??

Key Points:

1. A _________ changes the physical characteristics of a substance.

2. A __________ changes something into a new substance.

3. Changing color is evidence of a ___________.4. Changing phases or states of matter is

evidence of a __________________.

Summarizer: 1. What is the difference between a chemical

change and physical change?2. Is melting copper an example of a physical or

chemical change?3. How can you tell the answer to #2?4. Is a rusting nail an example of a physical or

chemical change?5. How can you tell the answer to #4?