Lesson Exemplar: Elements, Compounds, and Mixtures

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Katrina Washington
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1 Lesson Exemplar: Elements, Compounds, and Mixtures STATE PERFORMANCE INDICATORS State Performance Indicators SPI Distinguish among elements, compounds, and mixtures. SPI Identify properties of matter (e.g., physical: density, boiling point, melting point, or chemical: ability to rust or tarnish, be sour) or changes in matter (e.g., physical: phase change, shape, color, or chemical: formation of a gas or precipitation SPI Predict the products of a chemical reaction. Embedded Inquiry SPI 3221 Inq.2 Analyze the components of a properly designed scientific investigation. Science and Engineering Practices 1. Asking questions (for Science) 2. Developing and Using Models 3. Planning and Carrying Out Investigations 4. Analyzing and Interpreting Data 6. Constructing Explanations and Designing Solutions 7. Engaging in Argument from Evidence 8. Obtaining, Evaluating, and Communicating Information SPI 3221 Inq.3 Determine appropriate tools to gather precise and accurate data. SPI 3221 Inq.5 Defend a conclusion based on scientific evidence. SPI 3221 Inq.7 Compare conclusions that offer different, but acceptable explanations for the same set of experimental data. SPI 3221.T/E.1 Distinguish among tools and procedures best suited to conduct a specified scientific inquiry. Objective: The Scholar will Know: 1. The difference between element, compounds and mixtures. Understand: 1. The role of chemical reactions in the formation of compounds. 2. The composition of mixtures. 3. The relationship between consistency and type of mixture: heterogeneous and homogenous. 4. Separation processes of mixtures. Do: 1. Observe and characterize properties of elements, compounds, and mixtures. 2. Compare and contrast elements, compounds, and mixtures 3. Design and implement experiments to separate substances out of mixtures.

2 Engage: Students will be exposed to a career (Materials Science and Engineering) that uses the knowledge of elements and the combinations of elements to create new and beneficial products to advance our quality of life. The teacher will present the field using a PowerPoint or pdf file of the overview of the field of Martials Science and Engineering: Students will identify the importance of understanding the characteristics of the elements and how they change when combined with other elements. Teacher may question students on what scientific knowledge they need to be successful in this field. Teacher may probe around the usage of the periodic table of elements and their characteristic properties. Also questions surrounding how elements properties may change when mixed with other elements and How would this knowledge be beneficial?, should be explored. Explore Bead Sort Activity Before beginning the lesson, you will need to prepare the following class set: For one complete sample set, fill nine petri dishes or containers and label the lids as described in the table below. A Sharpie works well for the label, and a piece of clear tape over the writing will make the label more permanent. Dish Label Dish Contents Classification R Red beads only Pure substance, element B Blue beads only Pure substance, element Gn 2 Green beads, wired in pairs Pure substance, diatomic element BGn 2 P Several pieces, each consisting of one blue bead, two green beads, and a pearl wired together Pure substance, compound

3 PGn Several pieces, each consisting of a pearl wired to a green bead Pure substance, compound R Gn Several Some green pieces, beads each wired consisting in pairs, of as Pure substance, compound RGn + Gn 2 well as several pieces consisting of a mixture red bead wired to a green bead R + P + Gn 2 Loose red beads, loose pearls, and green beads wired in pairs mixture B+R Loose red beads and loose blue beads mixture Students should not be made aware of the content s classification. It may also be helpful to allow students to create the bead formations themselves so that they participate in the bonding of the elements and see the attachments for better understanding. Activity: Divide class into pairs of students. Instruct students not to open the dishes. One student from each pair should come forward to obtain a bag of samples. Ask students to sort the dishes into three groups based on similarities in the contents of the dishes. Emphasize that when students disagree with their partners about the classification, they should discuss their ideas until a consensus is formed. As a class, present and discuss the different ways that the students sorted the dishes. Ask the students to explain why they sorted the dishes the way they did. (Part of activity taken from wiki.coe.jmu.edu/msme/admin/download.html?attachid= ) Explain The teacher will use the discussion presented by students to frame the instruction on elements, compounds, and mixtures. The teacher will present the terms: element, compound, and mixture to allow students to assign vocabulary to their concepts. Students will develop of a graphic organizer that will address and characterize the following key terms: Element, Compound, Pure Substance, Mixture, Homogeneous, Heterogeneous, Colloid, Suspension, and Solutions. Visuals and examples should be presented.

4 Activity 1: During the teacher explanation, students should identify common compounds and identify the elements that compose them. Teachers should use this opportunity to connect the understanding of valence electrons to the chemically combining of elements to form compounds. The chemical equation should be presented for the compound formation. It is important to note the difference in properties of elements and the compounds that they make. It should also be noted that compounds cannot be physically separated because they are pure substances. Common Name Chemical Name Formula baking soda sodium hydrogen carbonate NaHCO 3 bleach (liquid) sodium bicarbonate sodium hypochlorite or NaClO hydrogen peroxide H 2 O 2 bleach (solid) sodium perborate NaBO 3 Borax sodium tetraborate Na 2 B 4 O H 2 O decahydrate brimstone sulfur S cream of tartar potassium hydrogen tartrate KHC 4 H 4 O 6 Epsom salt magnesium sulfate MgSO. 4 7 H 2 O heptahydrate Freon dichlorodifluoromethane CF 2 Cl 2 grain alcohol ethanol C 2 H 5 OH graphite carbon C laughing gas dinitrogen oxide N 2 O lime calcium oxide CaO limestone calcium carbonate CaCO 3 lye sodium hydroxide NaOH marble calcium carbonate CaCO 3 milk of magnesia magnesium hydroxide Mg(OH) 2 muriatic acid hydrochloric acid HCl oil of vitriol sulfuric acid H 2 SO 4 iron pyrite (fool s gold) iron disulfide FeS 2 quartz silicon dioxide SiO 2 quicksilver mercury Hg rubbing alcohol isopropyl alcohol (CH 3 ) 2 CHOH salt sodium chloride NaCl salt substitute potassium chloride KCl sugar sucrose C 12 H 22 O 11

5 Activity 2: Teacher will present the concept of Mixtures. The teacher will refer to the Explore activity that uses the beads to present visuals of types of mixtures. Teacher will give real life examples these types of mixtures. It is important that teachers note that mixtures can be physically separated. a. Element/ Element Mixture b. Element/ Compound Mixtures c. Compound/ Compound Mixtures d. Element/ Compound/ Compound Mixtures Activity 3: Teacher will present types of Mixtures as Suspensions (Italian Salad Dressing), Solutions (Cool- Aid) and Colloids (Shaving Cream) and Alloys (bronze, brass, and steel). Each will be presented and characterized with a visual example so that students can see each kind. Students will describe the molecular makeup by characterizing them as heterogeneous or homogeneous. Assessment: Students will compare and contrast in Venn diagram formation elements and compounds and Mixtures Students will also compare and contrast Colloids, Suspensions, and solution. Elaborate Activity #1 Comparing Compounds Students will investigate some of the characteristics of both elements and compounds. Materials: safety goggles, iron filings, powdered sulfur, paper towel, magnet, plastic bag or plastic wrap, heat source (Bunsen burner or candle), test tube, test tube tongs, container with cold water Student Directions: 1. Obtain a small amount of powdered sulfur. Place it on a piece of paper towel and carry it back to your desk. 2. Take a few minutes to make some observations about the element sulfur. Record your observations in the data table. What is its color? What does it feel like? Describe its texture. What does it smell like? Don t put your nose too close to it to smell it! Record your observations in the data table. 3. Use a plastic bag or plastic wrap to cover the magnet. Touch the covered magnet to the sulfur and record your observations. 4. Next obtain a small amount of iron filings and place them on a different paper towel. Carefully take them to your desk. 5. Take a few minutes to make some observations about the iron. Record your observations in the data table. 6. Draw the magnet toward the iron filings. Record your observations. 7. If iron filings have stuck to the magnet, wipe as many of them off as possible. 8. Mix the sulfur and iron. Record your observations. Also test the magnetic properties of the mixture and record your observations.

6 9. a. Combine the sulfur and iron filings from several students in a test tube and mix them. The test tube will be about 1/3 to 1/2 full of the mixture. (may be conducted by the teacher) b. Pick up the test tube with the test tube tongs. c. The test tube will then be heated over the flame of a Bunsen burner or candle for five minutes. CAUTION: Care needs to be taken to point the open end of the test tube away from people! e. After five minutes the test tube will immediately be immersed in cold water. f. If the test tube does not break, then it should be wrapped with paper towels and carefully broken with a heavy object. g. Carefully remove the contents while separating them from the pieces of glass. 10. With your sample of the sulfur iron compound, make some observations in the data table. Also test the magnetic properties of the sample with a magnet. 11. Answer the following questions. 1. Compare and contrast some of the properties of sulfur and iron. 2. What were the properties of the sulfur and iron mixture and how did they differ from those of the separate elements? 3. What part of the mixture responded to the magnet? 4. Is it possible to separate the sulfur and iron mixture into its individual parts? 5. Discuss how the properties of the sulfur and iron mixture changed after it was heated. Data Table Sulfur Iron Sulfur and Iron Mixture Sulfur and Iron Compound after Heating Color Texture and Feel Smell Magnetic Properties

7 Activity # 2 Heterogeneous and Homogeneous mixtures. Materials: dried beans, rice, peas, sunflower seeds, cup, piece of granite, grape juice, water, powdered fruit drink, sugar, magnifying glass Directions: 1. In a paper cup mix together dried beans, rice, peas, and sunflower seeds. 2. Describe the appearance of the mixture. Decide if it is well mixed or poorly mixed. Is it a heterogeneous or homogeneous mixture? Record your observations in the data table. 3. Obtain a piece of granite from your teacher. Describe its appearance. Use a magnifying glass for a closer examination of the rock. Decide if it is well mixed or not. Is it a heterogeneous or homogeneous mixture? Record your observations in the data table. 4. Your teacher will provide you with a glass of grape juice. Carefully examine the juice. Record your observations in the data table as you did for the other mixtures. 5. Pour a glass of cold water, then add a teaspoon of powdered fruit drink. Stir until the powdered fruit drink has dissolved. Next, add a teaspoon of sugar. Stir until the sugar has dissolved. Observe the drink. Record your observations in the data table. Questions: 1. Describe the difference between a heterogeneous mixture and a homogeneous mixture. 2. How do you know the bean-rice-pea mixture was a heterogeneous mixture? 3. List five examples of heterogeneous mixtures. 4. How do you know that both grape juice and the powdered fruit drink are homogeneous mixtures? 5. List five examples of homogeneous mixtures. Data Table Mixture Description Well mixed or not well mixed Homogeneous or Heterogeneous

8 Evaluate Mix It Up Party Students will participate in a class party that will serve as their assessment. The teacher will select several edible items: Salad with salad dressings (Italian and Ranch); Pizza; Kool- Aid; Soda; Yogurt; Fruit Salad; Fruit cups of only one type of fruit; Edible compounds: water, salt, vinegar, sugar, baking soda ; jell-o; etc. The teacher will also select items made up of only one type of element: silver, helium, etc. Each substance will be numbers and identified. Students will have to take a test sheet and identify the items as elements, compounds, or mixtures. The student will be required to identify the elements in the compound and the Chemical equation that led to the compound. Mixtures will be described by their components as well. Students will have to explain on their papers how these groups are alike and how they are different. After students turn in their papers, they may eat!!!!

INTRODUCTION TO MATTER: CLASSI F ICATION OF MATTER, PHYSICAL AND C He MICAL PROPERTIES, AND PHYSICAL AND CHEMICAL CHANGES

INTRODUCTION TO MATTER: CLASSI F ICATION OF MATTER, PHYSICAL AND C He MICAL PROPERTIES, AND PHYSICAL AND CHEMICAL CHANGES Experiment 3 Name: INTRODUCTION TO MATTER: 9 4 CLASSI F ICATION OF MATTER, PHYSICAL AND C He MICAL e PROPERTIES, AND PHYSICAL AND CHEMICAL CHANGES In this experiment, you will encounter various classification