1. Burning is a chemical change
Burning is a chemical change. When a substance undergoes a chemical change, a chemical reaction is said to take place.

2. Chemical Equations
A useful description of a chemical reaction tells you the substances present before and after the reaction.
The substances that undergo change are called __________________.
The new substances formed as a result of that change are called __________________.

3. Chemical Equations
Using Equations to Represent Reactions
During a chemical reaction, the reactants change into products. You can summarize this process with a ________________________. Reactants  Products

4. Carbon + Oxygen  Carbon dioxide
Chemical Equations
To describe the burning of charcoal, you can write reactants and products of the reaction in the following word equation:
Carbon + Oxygen  Carbon dioxide
And then write the reactants and products as ____________________________:
C + O2  CO2

5. Chemical Equations
A chemical equation is a representation of a chemical reaction in which the reactants and products are expressed as _____________.
You can read the equation C + O2  CO2 as
“ Carbon and oxygen react and form carbon dioxide,” or,
“The reaction of carbon and oxygen yields carbon dioxide.”

6. Chemical Equations
Conservation of Mass
During chemical reactions, the mass of the products is always equal to the mass of the reactants.
This principle is the law of conservation of _____. It states that mass is neither created nor destroyed in a chemical reaction.
Antoine______________established the principle of conservation of mass.
When charcoal burns, the mass of the carbon dioxide produced is equal to the mass of the charcoal and oxygen that reacted.

7. Chemical Equations
Whether you burn one carbon atom or six carbon atoms, the equation used to describe the reaction is always the same.