It Was Here Just a Moment Ago!

It Was Here Just a Moment Ago!

TAKS Objective 3TAKS Objective 3

• Substances have chemical and physical properties.

TEKS Science Concepts 8.9

TEKS Science Concepts 8.9

• The student knows that substances have chemical and physical properties. The student is expected to:

• (A) demonstrate that substances may react chemically to form new substances;

• (C) recognize the importance of formulas and equations to express what happens in a chemical reaction; and

• (D) identify that physical and chemical properties influence the development and application of everyday materials such as cooking surfaces, insulation, adhesive, and plastics.

Learning ObjectivesLearning Objectives

• 1.  The student will demonstrate chemical change as evidenced by a change in color.

• 2.  The student will measure temperature change as the result of a chemical reaction.

• 3.  The student will demonstrate a chemical reaction that produces gases.

• 4. The student will demonstrate a chemical change that results in the formation of a precipitant.

• 5. The student will use models to explain chemical formulas.

True or False

Chemicals are only found in chem labs

MISCONCEPTIONSMISCONCEPTIONSMISCONCEPTIONSMISCONCEPTIONS

Chemistry runs everyone and everything!

True or False

Physical and chemical changes never happen at the same

True or False

Energy changes during a chemical reaction

always give off heat

Energy changes during chemical reactions can give off heat and get hotter, absorb heat and get colder, give off light, sound, and electricity, etc.

Background

Physical vs Chemical Change

Physical Changes

Alter the size &/or shape

Cut, grind, dissolve

Phase Changes

Physical ChangesPhysical Changes

Physical Changes

Easily changed back to original form

Chemical Changes•New stuff is made

•Cannot change new stuff back into original form easily

•Chemical composition of new substance is different from original

Raw ChickenRaw Chicken Cooked Cooked ChickenChicken

Physical or Chemical?Physical or Chemical?Hint- Can you turn cooked chicken back Hint- Can you turn cooked chicken back

into raw chicken?into raw chicken?

5 Evidences of Chemical Change

1.Smell Change2.Color Change3.Energy change (hot, cold, light,

sound, electricity, etc.)4.Bubbles, fizzing, gas produced5.Precipitate (2 clears make a

cloudy)

#1 Smell Change

Baked cupcakes smell differently Baked cupcakes smell differently than batterthan batter

#2 Unexpected Color Change

Colorless methane burns blue

#3 Energy Change

As candle was burns, it gives off heat and light

#4 Bubbles or Fizzing

Alka Seltzer in Alka Seltzer in water makes water makes

carbon dioxide carbon dioxide gasgas

#5 Precipitate

Two clear solutions make a cloudy solution

Physical or Chemical?

You decide. . .

How do you know?How do you know?

Physical or Chemical?

You decide. . .

How do you know?How do you know?

Physical or Chemical?

You decide. . .

How do you know?How do you know?

ENGAGEENGAGE

•Balloon Gas–What happened?

EXPLOREEXPLORE

• Red Light – Green Light• For the Rust of My Life• Take a Powder• Clabbered Clumps• Witches Brew• Bubble Bubble Toil & Trouble• Fireworks (do as demo)• Milk of Magnesia

EXPLAINEXPLAIN

• Every reaction we did shows evidence of chemical change- what are 5?– Please- Precipitate (2 clears make cloudy)– Excuse- Energy change (heat, light, sound,

electricity)

– Coughs- Color change (unexpected)– Sneezes- Smell Change– Burps- Bubbles or fizzing (gas

produced)

ELABORATEELABORATE

• Abracadabra• Sweet Models• Irreversible Consequences• Chemistry at Home

– List or digital/ paper photos in PPT or poster

EVALUATEEVALUATE

•How many atoms of copper in 2 molecules Cu2O?

•What happens to atoms in chemical reactions?

•What physical properties can change in a chemical reaction?