Building Models of Elements, Compounds and Mixtures Classifying Matter and Physical versus Chemical Changes

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1 Building Models of Elements, Compounds and Mixtures Classifying Matter and Physical versus Chemical Changes SCIENTIFIC Introduction Magnetic demonstration models and a hands-on student activity. Samples of an element, a compound, and a mixture may look similar on the outside, but when we talk about these concepts with students, we are asking them to see what they look like on the inside. We want them to imagine atoms, molecules, and mixtures and notice how they are different. Concepts Mixtures Elements Compounds Formula writing Materials Paper clips (Jb), jumbo, at least 10 Paper clips (Sm), vinyl, 15 Paper clips (R), regular, 20 Safety Precautions Magnetic molecules, various colors (optional) The materials used in this activity are considered nonhazardous. Follow all standard classroom and laboratory safety precautions. Procedure 1. Hook two jumbo paper clips together to construct a model for Jb 2 and display as an example. 2. Construct models of the following formulas using paper clips and place them on the model sheet. Hint: Be symmetrical wherever possible. #1: 2 JbSm 2 #4: 2 Jb 2 R #2: 1 Jb 2 Sm and 1 R 2 #5: 4 R #3: 2 Sm and 1 R 3 #6: 3 Sm 2 Disposal The paper clips maybe saved and stored for future use or disposed of in the regular trash. Tips Magnetic molecules can be used for a brilliant display of the main concepts. Following the completion of the activity, the teacher may lead the students in a tile board assessment. Students working in partners are provided with an 8½ 11 piece of tile board, a dry erase marker, and an eraser. A transparency of models of atoms and molecules is placed on the overhead (see subsequent sheet). The students are asked a series of questions to which they reply by writing the answer on the tile board and flashing the answer for approval. Suggested questions are as follows: 1. List the pure substance(s) in line D. D1 and D2 2. List the mixture(s) in line B. B3 3. How many molecules are in B1? 4 4. How many atoms are in C3? Flinn Scientific, Inc. All Rights Reserved. Publication No

2 5. How many molecules are in C3? 2 6. How many molecules are in C1? 0 7. Which space could represent carbon dioxide, CO 2? A2 8. Which space could represent the major components of air? B3 The same transparency can also be used in a unit on chemical reactions for assessment. The following questions are posed: 1. Classify the reaction A3 B3. decomposition 2. Classify the reaction C1 + B2 A2. combination or synthesis 3. Classify the reaction D1 + D2 D3. single-replacement 4. Which space represents the products formed in the reaction between A1 and B1? C2 5. Classify the reaction between the substances in A1 and B1. double-replacement Answers to Worksheet Questions 1. List the number of each model (#1 6) alongside ONE of the following two headings. Mixtures: 2, 3 Pure Substances: 1, 4, 5, 6 2. Refer to the numbers listed in Question #1 under Pure Substances only. Classify the Pure Substances as Elements or Compounds. Pure Substances Elements Compounds R JbSm 2 Sm 2 3. Complete the following table. Jb 2 R Model Total Number of Atoms (paper clips) Total Number of Molecules #1 3 2 = 6 2 #2 5 1 = 5 2 # = = 3 3 #4 3 2 = 6 2 #5 1 4 = 4 4 #6 2 3 = 6 3 Connecting to the National Standards This laboratory activity relates to the following National Science Education Standards (1996): Unifying Concepts and Processes: Grades K 12 Evidence, models, and explanation Content Standards: Grades Flinn Scientific, Inc. All Rights Reserved.

3 Content Standard B: Physical Science, properties and changes of properties in matter Content Standards: Grades 9 12 Content Standard B: Physical Science, structure of atoms, structure and properties of matter References The paper clip activity was presented by Elna Clevenger as part of the CHEM-4 Team Woodrow Wilson National Fellowship Foundation Summer Workshops. The transparency is based on an article from the Journal of Chemical Education. The use of tile boards originated with Pam Fuginaka. The emphasis on models was inspired by the late Cliff Schrader. Flinn Scientific Teaching Chemistry elearning Video Series A video of the Building Models of Elements, Compounds and Mixtures activity, presented by Kathleen Dombrink, is available in Classifying Matter and Physical versus Chemical Changes, part of the Flinn Scientific Teaching Chemistry elearning Video Series. Materials for Building Models of Elements, Compounds and Mixtures are available from Flinn Scientific, Inc. Catalog No. Description AP6497 Magnetic Molecules, Red, Set of 20 AP6498 Magnetic Molecules, White, Set of 20 AP6499 Magnetic Molecules, Yellow, Set of 20 AP6500 Magnetic Molecules, Green, Set of 20 AP6926 Magnetic Molecules, Blue, Set of 20 Consult your Flinn Scientific Catalog/Reference Manual for current prices Flinn Scientific, Inc. All Rights Reserved.

4 Building Models of Elements, Compounds and Mixtures Worksheet Questions 1. List the number of each model (#1 6) alongside ONE of the following two headings. Mixtures: Pure Substances: 2. Refer to the numbers listed in Question #1 under Pure Substances only. Classify the Pure Substances as Elements or Compounds. Pure Substances Elements Compounds 3. Complete the following table. Model Total Number of Atoms (paper clips) Total Number of Molecules #1 #2 #3 #4 #5 # Flinn Scientific, Inc. All Rights Reserved.

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