Chapter 6 Lesson 3, "Compounds and Mixtures"

Materials:

• Worksheet, "Compounds and Mixtures: Terms Review" may use the on-line version.

Objective:

• Students will explain the differences among compounds, elements, and mixtures.
• Students will identify some common compounds.
• Students will recognize the formula for a compound.

Anticipatory Set:* There are 97 natural elements. Are there only 97 different substances on earth? Why? Students will observe the properties of iron and sulfur. Show the students a sample of sulfur and iron. Use this table:

After heating the compound students will again identify the properties. Why did the properties change? Can the sulfur and iron be physically separated again? What have we formed?

Define compound:

Teacher Input:* How is water like the above demonstration? Explain that water is made of hydrogen and oxygen. Both very explosive yet water does not even burn (Fighting Fire)? In another case sodium (a metal which will explode in water) is combined with chlorine (a poisonous gas) and we get salt. How do we identify a compound? The easiest way is with its chemical formula. Show the chemical formula for water. Identify its different parts. H2O and its molecule. Go through the compounds on the table on page 143, Have the students tell what is in them one site at a time. NaCl, Fe2O3, NaHCO3, CaCO3, CO2. Students will have to use the periodic table from the book.

Would this soil be considered a compound? How about air? What about pond water? These items are not compounds. They are mixtures. Mixtures can be either mixtures of elements (Remind the students of the sulfur/iron demonstration, 1, 2, 3, 4,), compounds, or both. Define Mixture.

Guided Practice:* Compose a Venn diagram with the students comparing and contrasting compounds and mixtures. Have a student from each site read the notes in the margins on Pages142-145. These contain a lot of useful information about compounds and mixtures. Answer the questions on Page 146 with the students.

Independent Practice:* Students should complete the worksheet, "Compounds and Mixtures: terms review".

Check for Understanding:* Students should complete the Quiz for Lesson 6-3.

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-1 Students will understand models describing the nature of molecules, atoms, and sub-atomic particles and the relation of the models to the structure and behavior of matter (Structure of Matter);
• SCI A-2 Students will understand the physical, chemical, and nuclear changes and interactions that result in observable changes in the properties of matter (Changes and Interactions of Matter);

• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and: