What is a Chemical Reaction?

This lesson plan contains mutiple differentiated levels that demonstrate the changes that occur in a chemical reaction as well as the Law of Conservation of Mass. Choose the Chapter 6 PDF downloads located at this website to obtain multiple activities that help to explain chemical reactions.

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What is a Chemical Reaction?

Standards & Objectives

Learning objectives:

Objective

Students will be able to explain that for a chemical reaction to take place, the bonds between atoms in the reactants are broken, the atoms rearrange, and new bonds between the atoms are formed to make the products. Students will also be able to explain that in a chemical reaction, no atoms are created or destroyed.

Key Concepts:

A physical change, such as a state change or dissolving, does not create a new substance, but a chemical change does.
In a chemical reaction, the atoms and molecules that interact with each other are called reactants.
In a chemical reaction, the atoms and molecules produced by the reaction are called products.
In a chemical reaction, only the atoms present in the reactants can end up in the products. No new atoms are created, and no atoms are destroyed.
In a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.

Essential and guiding questions:

Why do you think the flame goes out when we put a jar over the candle?
When a candle burns for a while, it eventually gets smaller and smaller. Where does the candle wax go?
Where do the atoms come from that make the carbon dioxide and the water on the right side of the equation?
Are atoms created or destroyed in a chemical reaction? How do you know?
In a physical change, like changing state from a solid to a liquid, the substance itself doesn’t really change. How is a chemical change different from a physical change?

Lesson Variations

Blooms taxonomy level:

Understanding

Extension suggestions:

Extension:

Introduce two other combustion reactions and have students check to see whether or not they are balanced.

Tell students that, in addition to the wax and methane, some other common hydrocarbons are propane (the fuel in outdoor gas grills), and butane (the fuel in disposable lighters). Have students count the number of carbon, hydrogen, and oxygen atoms in the reactants and products of each equation to see if the equation is balanced. They should record the number of each type of atom in the chart on their activity sheet.

Helpful Hints

Materials for the Demonstration

Tea light candle or other small stable candle
Matches
Glass jar, large enough to be placed over the candle

Materials for Each Student

Atom cut-outs from the activity sheet
Sheet of colored paper or construction paper
Colored pencils
Scissors
Glue or tape

References

Contributors:

cecelia patrick

Originator:

Ayers Institute for Learning & Innovation

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