Do Now:Explain this joke.

The last 2 weeks we have…

investigated how evidence of chemical reactions indicates that new substances with different properties are formed.

Evidence of a chemical reaction: (chemical change)

• Production of a gas (bubbling, fizzing or foaming)• A change in temperature or light (an energy change)• Appearance of a precipitate (solid material)• A change in color

Chemical Reaction Dehydration of sugar…

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Physical properties

White crystal To yield

Black crystal/powder and white gas

Chemical equation

C12H22O11 12 C + 11 H2O (vapor)

Visual model

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Number of atoms 12 carbons 22 Hydrogen 11 oxygen

12 carbons 22 hydrogens 11 oxygens

Let’s make some visual models with SKITTLES

You will be able to…8.5(D) recognize that chemical formulas are used to identify substances and determine the number of atoms of each element in chemical formulas containing subscripts;8.5(F) recognize whether a chemical equation containing coefficients is balanced or not and how that relates to the law of conservation of mass.

KeyRed-Chlorine

Orange-Sodium

Yellow-OxygenGreen-Hydrogen

Purple- Carbon

H2O

Review: How to make a molecule…

No Subscript, There is only 1 atom of oxygen in the molecule

Subscript

Visual modelFormula

H2O

Review: How to make a molecule…

No Subscript, There is only 1 atom of oxygen in the molecule

Subscript

Visual modelFormula

H2O2

6 H2O

Review: How to make a molecule…Visual modelFormula

Coefficient- How many molecules you have.

H2O

1 molecule of H2O

3 H2O

3 molecules of H2O

Let’s now model another chemical equation with our SKITTLES…

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Chemical equation

C + O2 CO2

Visual model

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Word equation

To yield

Number of atoms

1 atom carbon reacts with 1 molecule of oxygen 1 molecule of CO2

1 carbon 2 oxygen 1 carbon 2 oxygen

Is it a balanced equation? How do we know?

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Chemical equation

C + O2 CO2

Visual model

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Word equation

Number of atoms

1 atom carbon + 1 molecule oxygen 1 molecule CO2

1 carbon 2 oxygen 1 carbon 2 oxygen

Law of Conservation of Mass

Matter is not created or destroyed, it just changes forms.In a chemical reaction…

More practice…

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Chemical equation

2C + 2O2 3CO2

Visual model

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Word equation

To yield

Number of atoms

2 atoms carbon react with 2 molecule oxygen

3 molecules CO2

Is it balanced?

2 carbons 4 oxygen 3 carbons 6 oxygens

The model above is best represented by:a. H2O

b. 2OHc. HOOHd. H2O2

The above model shows:a. 10 atomsb. 2 moleculesc. 2CH3Cl

d. All of the above

6CO2+ 6H20+ Sun’s light C6H12O6+6O2

The above reaction…a. is photosynthesisb. Is respirationc. Transforms radiant energy into chemical

energyd. Both a and c.

Organic Molecules all contain…

a. Sulfurb. Carbonc. Oxygend. nitrogen

All of the following are organic molecules except…

a. C6H12O6

b. CH4

c. C6H6O

d. H20