1. Lesson 20 Breaking Down a Compound

2. Objectives
Conduct an experiment to determine what happens when electricity is passed through water.
Investigate some physical and chemical properties of gases.
Discuss the differences between compounds and elements.

3. Getting Started In your notebook, do the following:
Write a definition for the terms “element” and “compound”.
For each term, write down two examples.

4. Lesson 20 - (1-1) Vocabulary
Compound: A pure substance consisting of two or more elements combined such as sodium and chlorine which make sodium chloride.
Element: A substance that can not be broken down into any other substances by chemical or physical means (except by nuclear reaction).
Electrolysis: The process by which some liquid compounds or some compounds in solution are split into their constituent parts by passing electricity through them.

5. Vocabulary
Decomposition Reaction: A reaction in which a single compound breaks down to form two or more simpler substances.
Burning: A rapid chemical reaction between a substance and a gas that produces heat or light. Most burning or combustion takes place in air and has oxygen as one of its reactants.

6. Lesson 20 -
Question
Can compounds (such as water) be broken down?

7. Lesson 20
If….. then…. because…
Hypothesis 7

8. SAFETY
Wear safety goggles throughout inquiry.
Tie back long hair.

9. Lesson 20 -
Procedure
Follow procedure in Student Book, pp

10. Lesson 20 -
Results
Use Student Sheet 20.1

11. Lesson 20 -
Conclusion
Water is a compound made of the elements hydrogen and oxygen.
Compounds are pure substances made of more than one element.
Elements are pure substances that cannot be broken down.
Some pure substances are composed of two or more pure substances combined.
Compounds of pure substances can be broken down by a chemical reaction…..