Unformatted text preview: ChemActivity 2 Types of Matter; Chemical and Physical Changes (How can we classify matter?) Model 1: Examples of some pure substances at room temperature Item Classiﬁcation State (or states) Formula aluminum element solid A|(s) hydrogen element gas H2(g) mercury element liquid H90) baking soda compound solid NaHCO3(s) table salt compound solid NaCl(s) water compound liquid H20(|) Critical Thinking Questions: Refer to Model 1 to help you answer Critical Thinking Questions (CTQs) 1-3. 1. What is the formula for hydrogen gas? For liquid water? 2. How can you distinguish elements from compounds based on their chemical formulas? Consult with your team and write your consensus answer in a complete sentence or two. 3. Based on your answer to CTQ 2, complete the definition for A compound is composed of at least different that are combined chemically. Model 2: Examples of some mixtures at room temperature Item Classification State (or stat-es) Formula (or formulas) hydrogen peroxide solution (3%) salt water homogeneous mixture aqueous solution H200) and NaCl(aq) homogeneous mixture aqueous solution H200) and H202(aq) coffee (“biack”) homogeneous mixture aqueous solution H200) and many others muddy water heterogeneous mixture liquid + solid H200) and other stuff Critical Thinking Questions: 4. The 3% hydrogen peroxide solution available in drugstores is 97% water. What is the formula for the hydrogen peroxide present in this solution (consult Model 2)? 5. Elements and compounds are considered pure substances. Compare Models 1 and 2. How does a substance differ from a mixture? Discuss with your team and write a consensus answer. - 5 ~' CAOZ 6. Devise a team hypothesis about the meaning of the labels (3), (I), (g), and (aq) on the formulas. Information: States of matter Matter can be classified by its physical state (or phase): solid, liquid, or gas. Most solids can be melted and even vaporized if the temperature is high enough. The phase labels (5), (I), or (9) can be written after a formula to signify the physical state. So, H20(g) would mean gaseous water, i. e., water vapor. Model 3: Equations for some chemical and physical changes Equation Type of change H20“) —> H2003) physical 2 H2(g) + 02(9) ~> 2 H20(g) chemical III 2 H202(aq) -~> 2 H200) + 02(9) chemical C3H60(l) ") C3H60(g) Critical Thinking Questions: Questions 7—10 refer to Model 3. For each question, manager: ask a different team member to begin discussion by explaining his or her answer to the team. 7. Write a complete sentence to describe in words (no formulas) what is happening in Equation I. Why is this process considered to be a physical change? 8. Describe in words what is happening in Equation II. Why is this a chemical change? 9. Describe in words what is happening in Equation III. Why is this a chemical change? 10.The formula for acetone is C3H60. Without using formulas, write a sentence to describe describe what is happening in Equation IV. Is this a chemical or physical change? Fill in the blank in the Model. CAOZ - 6 * Model 4: Flow chart for classifying matter Matter (pure) Substance Com pound Homogeneous Heterogeneous Information: Classifications of matter Matter can be divided into two main types: pure substances and mixtures of substances. A substance cannot be separated into other kinds of matter by physical processes such as filtering or evaporation, and is either an element (e. 9., aluminum) or a compound (e. 9., H20). Compounds are made of two or more elements chemically combined. The elements themselves cannot be separated into simpler substances even by a chemical reaction. On the other hand, mixtures can be separated by physical means. Mixtures that have the same composition throughout are called homogeneous (e. 9., salt water); those that do not are called heterogeneous (e. 9., Italian salad dressing). Critical Thinking Questions: 11. Have one team member reread your team’s answer to CTQ 5 out loud. Add to or revise it if necessary. 12. As a team, try to brainstorm a physical method that you could use to separate salt water into two pure substances. Write your idea here. Model 5: Some different representations of the water molecule 0 , .' H20 HOH i-i—O—H H/ \H f.)- ' J formulas Lewis structures bali-and»stici< Spacefilling Critical Thinking Questions: 13.The “2” in H20 is subscripted (written below the fine). Based on Model 5, what do subscripts following an element in a formula represent? 14. Look at a periodic table of the elements. About how many elements are known? 15. Approximately how many elements are metals? (Estimate, don’t count!) _ 7 _ CAOZ 16.There are thousands of organic compounds known—compounds formed out of only a few different elements (carbon, hydrogen, oxygen, nitrogen). How might this be possible? 17.Did everyone in your team contribute to the activity today? If so, explain how. If not, identify what individuals need to do to ensure participation by ali in the next session. Exercises: 1. Write the formula of each molecule for which the ball—and—stick structures are shown. Key: 9 = carbon J = oxygen J = hydrogen 2. Using a periodic table, identify the elements represented in each formula, and state the number of atoms of each element in the formula. The ﬁrst one has been done for you. a. NH3 (ammonia) one nitrogen atom, three hydrogen atoms b. CGHIZOE (glucose) c. Mg(OH)2 (milk of magnesia) d. H2804 (suifuric acid, “battery acid”) e. C17H18F3NO (fluoxetine, Prozac) 3. Using the flow chart in Model 4 to help you, first classify each of the following as either a mixture or pure substance. Then, for each substance, teil whether it is an element or a compound. For each mixture, tell whether it is homogeneous or heterogeneous; then list two or more components of the mixture. a. a lead weight b. applejuice CAOZ - 8 - c. baking soda (NaHCOa) d. air e. a 14~karat gold ring f. a 24»karat gold coin g. helium in a balloon h. beach sand i. concrete j. whole blood k. carbon dioxide In the space below, draw a picture of three water molecules in the ball-and-stick representation. Which of the choices below (I or 11) would best represent the three molecules you drew in Exercise 4? Explain your choice. Choice 1 Choice 11 H503 3 H20 Can you think of some commercial products you might have at home that are heterogeneous mixtures? List one or more“ . Learn the names and symbols of the elements your instructor suggests. A good starting point is the first 30 elements, plus Br, Sr, Ag, Sn, I, Ba, Pt, Au, Hg, Pb. Spelling counts! You do not need to memorize any numbers, as a periodic table will always be available for your use. Read the assigned pages in the text, and work the assigned problems. _ 9 _ CAOZ ...
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Critical Thinking Resources for Middle School TeachersBy Room 241 Team • November 9, 2012
Middle school teachers of all subjects are interested in fostering critical thinking in their classroom, but it’s not always an easy task to incorporate in the never-ending quest to match lesson plans to state learning standards. Here are seven resources that will easily add critical thinking to your lesson plans.
The Critical Thinking Community
The Critical Thinking Community is a resource site designed to encourage critical thinking in students. There are teaching strategies, a glossary of important terms, as well as articles by thought leaders in critical thinking, such as one by Bertrand Russell on the importance of developing critical thinking skills. Visit the site.
Here are some recommended pages for critical thinking strategies for the middle school classroom.
- Teaching tactics: Strategies teachers can use to encourage critical thinking in class. For example, asking students to read the instructions of an assignment and then repeat them in their own words. Visit the page.
- Remodeled lessons: How to take a routine lesson plan and remodel it to foster critical thinking. The page has five standard lesson plans, a critique of why they should be changed, and suggestions for improving the lesson plan. Visit the page.
- 35 dimensions of critical thought: Strategies are organized into three groups: Affective, Cognitive Macro-Abilities, and Cognitive Micro-Skills. Each strategy details its importance for student development. Visit the page.
Success story: tips for teaching critical thinking
KIPP King Collegiate High School has developed 10 ideas for teaching critical thinking. These methods are applicable for middle school aged students, giving them exposure to thinking critically before arriving to high school. One notable technique from KIPP is to teach students to constantly ask questions. Visit the page.
Critical thinking in the 21st century
Microsoft Education offers material for teaching critical thinking for the 21st-century student. What’s special about this guide is its focus on thinking critically on the Internet. Lesson plans focus on fine-tuning search skills, how to evaluate discoveries and then incorporate findings in student work. Visit the site.
Creative and critical thinking activities
On teachers.net Gazette, a teacher named Emmy recommends five specific activities that are easy to use, take little preparation, and stimulate creative thinking. The most popular feature of this site is its teacher collaboration. Visit the page.
Back to basics
This site details the basics about critical thinking: what it is, the characteristics, and why it should be taught. It also provides several differing perspectives about critical thinking for readers to consider. Different teaching strategies are also discussed, plus links to helpful resources. Visit the site.
Riddle me that
BrainDen.com has a large number of critical-thinking riddles and brain teasers that can be used in the classroom. The answers are provided for the teacher as well as tips for stimulating further discussion on the topic. Teachers can use the exercises as warmup activities at the beginning of class, or at the end of class on days when work is unexpectedly completed early. Visit the site.
Discovery Education has a “Brain Boosters” section listing specific logical thinking challenges and brain teasers that students love. The activities can be done with groups or individually. The answers are provided for the teacher. Visit the site.Tags: Engaging Activities, Middle School (Grades: 6-8)