Science Chemistry Unit 03 Exemplar Lesson 01: Models of the Atom

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1 Unit 03 Exemplar Lesson 01: Models of the Atom This lesson is one approach to teaching the State Standards associated with this unit. Districts are encouraged to customize this lesson by supplementing with district-approved resources, materials, and activities to best meet the needs of learners. The duration for this lesson is only a recommendation, and districts may modify the time frame to meet students needs. To better understand how your district may be implementing CSCOPE lessons, please contact your child s teacher. (For your convenience, please find linked the TEA Commissioner s List of State Board of Education Approved Instructional Resources and Midcycle State Adopted Instructional Materials.) Lesson Synopsis This lesson focuses on the modern theory of the atom and basic atomic structure. Students first experience and discuss the challenges of scientifically understanding what cannot be seen. Atomic structure, isotopes, and calculating average atomic mass are introduced. Next, students study several historical atomic models, focusing on the limitations of each. Students then develop understanding of the electromagnetic spectrum and associated mathematical relationships involving wavelength, frequency, and energy. Finally, students create a product illustrating the historical development of atomic theory including major scientists and their ground-breaking investigations. TEKS The Texas Essential Knowledge and Skills (TEKS) listed below are the standards adopted by the State Board of Education, which are required by Texas law. Any standard that has a strike-through (e.g. sample phrase) indicates that portion of the standard is taught in a previous or subsequent unit. The TEKS are available on the Texas Education Agency website at C.6 concepts. The student knows and understands the historical development of atomic theory. The student is expected to: C.6A Understand the experimental design and conclusions used in the development of modern atomic theory, including Dalton's Postulates, Thomson's discovery of electron properties, Rutherford's nuclear atom, and Bohr's nuclear atom. Supporting Standard C.6B Understand the electromagnetic spectrum and the mathematical relationships between energy, frequency, and wavelength of light. Supporting Standard C.6C Calculate the wavelength, frequency, and energy of light using Planck's constant and the speed of light. Supporting Standard C.6D Use isotopic composition to calculate average atomic mass of an element. Scientific Process TEKS Supporting Standard C.1 Scientific processes. The student, for at least 40% of instructional time, conducts laboratory and field investigations using safe, environmentally appropriate, and ethical practices. The student is expected to: C.1A Demonstrate safe practices during laboratory and field investigations, including the appropriate use of safety showers, eyewash fountains, safety goggles, and fire extinguishers. C.2 Scientific processes. The student uses scientific methods to solve investigative questions. The student is expected to: C.2F Collect data and make measurements with accuracy and precision. page 1 of 16

2 C.2H Organize, analyze, evaluate, make inferences, and predict trends from data. C.2I Communicate valid conclusions supported by the data through methods such as lab reports, labeled drawings, graphs, journals, summaries, oral reports, and technology-based reports. C.3 Scientific processes. The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to: C.3A In all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student. C.3D Evaluate the impact of research on scientific thought, society, and the environment. C.3F Research and describe the history of chemistry and contributions of scientists. GETTING READY FOR INSTRUCTION Performance Indicators High School Unit 03 PI 01 In a laboratory report, given the isotopic composition of one or more natural elements, show the steps necessary to calculate the average atomic mass of each of the elements. Standard(s): C.2I, C.6D ELPS ELPS.c.1G, ELPS.c.3C, ELPS.c.5F High School Unit 03 PI 02 Produce a product (such as a timeline, brochure, or poster) that will show the development of the modern model of the atom by identifying scientists and their experiments, conclusions, and contributions. Include the historically important work of Dalton, Thomson, Rutherford, Bohr, and Schrödinger. Standard(s): C.3A, C.3D, C.3F, C.6A ELPS ELPS.c.1C, ELPS.c.4J, ELPS.c.5G Key Understandings Isotopes of an element have different atomic masses but the same atomic number. What is an isotope? The average atomic mass of an element is calculated based on its isotopic composition. How is the average atomic mass of an element calculated? The modern model of the atom was developed as the result of the experiments of a number of scientists over an extended period of time. What is Thomson s contribution to our understanding of the atom? What are Dalton s Postulates? What was Rutherford s experiment? What is the Bohr model of the atom? How is the modern (Schrodinger) model different from the Bohr model? What are the limitations of the various atomic models? Vocabulary of Instruction atom subatomic particles nucleus protons neutrons electrons electromagnetic spectrum wavelength frequency photon Planck s constant speed of light isotope spectroscope mass number atomic number nuclear symbol hyphen notation average atomic mass page 2 of 16

3 Materials 1 cm sphere (1 per teacher for demonstration) beans (dry, 3 types such as black, Great Northern, and pinto, 1 bag each per class) calculators (1 2 per group) cork stopper (1 per teacher for demonstration) cups (plastic, 3 per group) dressmaker s pin (with spherical head, 1 per teacher for demonstration) electronic balance (1 per group) fan (electric, 1 per teacher for demonstration) felt (approx. 40 x 40 cm piece per teacher for demonstration) fluorescent paper (for fan blades, see Advance Preparation) lentils (1 bag per teacher for demonstration) marker cones (12 per teacher for demonstration) miniature light bulb (powered by battery, 1 per teacher for demonstration) photo (of a large aircraft carrier, see Advance Preparation, for projection) string (20 meters per teacher for demonstration) UV light source (1 per teacher for demonstration) Attachments All attachments associated with this lesson are referenced in the body of the lesson. Due to considerations for grading or student assessment, attachments that are connected with Performance Indicators or serve as answer keys are available in the district site and are not accessible on the public website. Teacher Resource: PowerPoint: Unit 03 Lesson 01 Teacher Resource: Cube Template (see Advance Preparation, 1 of each type per 4 students) Handout: Element Investigation (1 per group, see Advance Preparation) Handout: History of Atomic Theory PI II (1 per group) Teacher Resource: Performance Indicator II Instructions KEY Teacher Resource: Performance Indicator I Instructions KEY Resources None Identified Advance Preparation 1. Prior to Day 1, assemble the Number Cubes and Shape Cubes, using the Teacher Resource: Cube Template. Create enough Cube Templates on white cardstock in order to have one of each type of cube per group of four students. Cut out the pattern, fold it into a cube, and secure each with tape. Alternatively, construct larger cubes from cubical boxes. Shading is important so be sure to follow the template precisely. The bottom face of every cube will be blank. 2. Prior to Day 2: Find an appropriate location to demonstrate the Atom to Scale model. A gym or outdoor field would be appropriate. Set up a cone or other marker analogous to the nucleus. Using a 20-meter long string as a guide, place additional markers this distance from the cone forming a circle (You could use a bright colored spray paint to mark the area if permitted.). Conduct an Internet search to find a photo for projection of a large aircraft carrier, such as a Nimitz class aircraft carrier, to use in the Mass is the Nucleaus model. For the Fan Analogy, securely fasten a piece of fluorescent paper to each blade of the fan. 3. Prior to Day 3: Obtain 1 lb bags of three types of of dry beans, such as kidney, navy, and pinto beans. Make samples of Newium for each group doing the investigation to find percent composition and average atomic mass. Each sample should be about the page 3 of 16

4 same percent composition of Firstium, Secondium, and Thirdium. Put each sample in a plastic cup. Each group will need two additional cups. Conduct an Internet search to find a chart of electromagnetic spectrum for projection. 4. Prior to Day 4, review the Teacher Resource: Performance Indicator II Instructions KEY to determine your expectations for the assessment. Locate and preview resourced you will allow students to use for their research. 5. Prior to Day 7: Review the Teacher Resource: Performance Indicator I Instructions KEY to determine your expectations for the assessment. Note: The PI requires advance preparation. Gather appropriate data sets (isotopic composition data from naturally occurring elements) for the Evaluate Performance Indicator. Each students will need a different data set. Isotopic abundances for the Performance Indicator may be found by conducting a browser search for "exact masses and isotopic abundances". Determine the expectations for the lab report and rubric you will use for Performance Indicator I. You may wish to refer to the resource: Creating the Notebook: A Tool for Evaluating Student Work for a sample of a science lab and rubric. The manual is located in the Instructional Resources section of the website. 6. Prepare attachments as necessary. Background Information Our current theory of the basic structure of the atom is the result of historically important work by Thomson, Dalton, Rutherford, and Bohr. The nuclear atom, with protons and neutrons in the nucleus and electrons outside the nucleus, was modified by Schrodinger and others to become the current quantum mechanical model. The foundations of this model are the electromagnetic spectrum and mathematical relationships between energy, frequency, and wavelength of light. Even the best models have shortcomings. In this lesson, it is imperative that students are encouraged to think about and discuss how the historical models differ in terms of what they represent. Students have probably heard of isotopes from the perspective of radioactivity and will study more about them in Unit 13, Nuclear. The average atomic mass of a naturally occurring element is a function of its isotopes and their respective abundance in nature. For example, chlorine has two naturally occurring isotopes, Cl-35 and Cl-37, with an abundance of about 76% and 24% respectively. The average atomic mass, 35.5 amu, is then sum of the mass of each isotope times its relative abundance (35 x x 0.24 = 35.5). STAAR Note: The use of the periodic table to identify and explain the properties of chemical families and periodic trends will be tested as Readiness Standards under Reporting Category 1: Matter and the Periodic Table. Included in the STAAR Reference Materials is a periodic table of the elements that includes the lanthanide and actinide series. Shown within the table are the name, symbol, atomic number, and atomic mass with mass numbers in parentheses those of the most stable or most common isotopes. INSTRUCTIONAL PROCEDURES EXPLORE/EXPLAIN Atomic Models Suggested Days 1 (continued) and 2 1. Ask students to individually sketch and label a diagram of an atom in their science notebooks, based on what they remember from previous science classes. 2. Walk around the room to get a sense of what students recall about atomic structure. 3. Review the basic structure of an atom with students by creating a sketch based on student responses to the following questions. Make adjustments, as the discussion dictates, and reach a class consensus of an accurate representation. Note any areas of confusion and/or disagreement. When reviewing the basic structure of an atom, call on students whose sketches indicate a strong understanding of a basic model. 4. Continue the discussion, utlizing the following questions: What are the subatomic particles in an atom? Protons, neutrons, Materials: miniature light bulb (powered by battery, 1 per teacher for demonstration) marker cones (12 per teacher for demonstration) string (20 meters per teacher for demonstration) dressmaker s pin (with spherical head, 1 per teacher for demonstration) cork stopper (1 per teacher for demonstration) 1 cm sphere (1 per teacher for demonstration) photo (of a large aircraft carrier, see page 4 of 16

5 electrons What do you know about protons? Positively charged; found in the nucleus; dictates the identity of the atom; comparable in size to neutron but smaller than electron What do you know about neutrons? Neutral; found in the nucleus; comparable in size to proton but smaller than electron What do you know about electrons? Negatively charged; found outside the nucleus; very small compared to neutron and proton What is between the subatomic particles in an atom? Nothing; empty space; a void 5. Intructions: The following atomic models shared are intended to suggest what atoms are like. They are not intended to show you what atoms look like. For each model shown, make a sketch in your science notebooks and a T-Chart. Label the first column of the T-chart similarities and the second column limitations. For each atomic model, we will discuss both how the model is used to explain behavior of atoms and the limitations of the model. 6. Use the slides corresponding to the Explore/Explain: Modeling the Atom section from the Teacher Resource: PowerPoint: Unit 03 Lesson 01 to help guide progress through the activity. 7. Remind students to document and sketch all models in their science notebooks. 8. When students first learned about atomic structure, the nucleus and electrons were like a mini solar system - the Sun and planets. While the model is highly flawed, it can be useful. Use the slides to compare and contrast the atom and solar system. 9. The moth and light model, based upon moths fluttering around light bulbs at night, helps to show the 3D nature of the atom as well as the random motion of electrons within the atom. 10. To demonstrate, hold a miniature light bulb (the nucleus) with one hand. Move your other hand (an electron) around the bulb in all directions with a fluttering motion, much like a moth fluttering around a light. 11. Point out that like the moth, we cannot predict where an electron will be at any particular time. Also, like the moth, there is an identifiable space in which an electron is most likely to be found. 12. Point out the limitations of the model: the model is millions of times too compressed, the electron is too large compared with the nucleus, and we cannot come close to modeling the speed at which an electron moves an electron in a hydrogen atom travels at 2.42x10 8 cm/sec. 13. The Atom to Scale model shows the parts of an atom to the same scale as the overall size of the atom. It also illustrates that an atom is mostly empty space. Advance Preparation, for projection) fan (electric, 1 per teacher for demonstration) fluorescent paper (for fan blades, see Advance Preparation) UV light source (1 per teacher for demonstration) lentils (1 bag per teacher for demonstration) felt (approx. 40 x 40 cm piece per teacher for demonstration) Attachments: Teacher Resource: PowerPoint: Unit 03 Lesson 01 (from previous activity) Instructional Notes: This activity consists of a series of teacher-led discussions and demonstrations of atomic models, all aimed at highlighting the question: What s wrong with this model? The models include: the atom and solar system, moth and light, atom to scale, mass is in the nucleus, electron clouds: the fan analogy, and electron clouds: the probability cloud. Some models are summarized through demonstrations, but NOT in the Teacher Resource: PowerPoint: Unit 03 Lesson 01. It is important to clarify the idea of empty space existing between particles. It is important that students understand that the atomic models discussed do not show what atoms look like; rather they model how atoms behave. You may want to introduce the Elaboration/Evaluation project at the earlier in the lesson to allow student groups more time to prepare. Notebooks: Students document and sketch all models in their science notebooks. 14. The model requires a large amount of space and so it s best to go outdoors or to a gym or other large space (See the Advance Preparation for set up and location requirements of the models.). A limitation of this model is that a real atom is not flat (2-dimensional). Our page 5 of 16

6 model should extend in a spherical space, both upward and downward, as far as it extends outward. Stand on the X holding a dressmaker s pin with a spherical head (stuck in a cork for easy handling), and instruct students to gather around. Explain that the pinhead represents the nucleus. Have the students spread out to the outer perimeter of the 20 meter radius circle, representing the outer limits of the atom. Discuss the model and its limitations. 15. The Mass is in the Nucleus model is intended to help students understand that an atom is mostly empty space and the nucleus is very dense. A 1 cm sphere composed of tightly packed nuclei would weigh 133,000,000 tons. This is equivalent to squeezing more than 1400 Nimitz class aircraft carriers into a 1 cm sphere. 16. To help students visualize, display a 1 cm sphere and large photo of an aircraft carrier (see Advance Preparation). 17. Modeling electrons: the Fan Analogy. The area occupied by an electron as it moves about an atom at high speed can be compared to a cloud of varying density, much like that of the blur of whirring blades of a fan. Show students a fan operating at various speeds to illustrate this idea. To make the fan-blade cloud more visible, securely fasten a piece of fluorescent paper to each blade (see Advance Preparation). For a more spectacular effect, shine a UV light on the spinning fluorescent blades in a darkened room. Be sure to point out that that while the fan blades move quite predictably within a flat, well-defined space, electrons more quite unpredictably within a 3D space that has now well-defined borders. 18. Modeling electrons: the Probability Cloud. Limitations include that the model is flat whereas an electron cloud is 3D. Hold a fistful of lentils about 5 cm above the center of a piece of felt. Allow them to trickle from the bottom of your fist onto the felt. Have the students make note that they form a probability cloud pattern. The denser parts represent locations where there is a high probability that a lentil will land; the sparser areas represent a lower probability that lentils will land there. Have students note that each lentil represents a location occupied by the electron at some point in time, rather than the number of electrons in the model. 19. Make the connection between gathering evidence to predict what is on the bottom of a cube (during the Engagement activity) and the scientific processes related to evidence about the structure of the atom. Neither can be physically seen. EXPLORE/EXPLAIN Isotopic Composition Suggested Day 3 1. Divide the class into groups of 2 3 students. Propose the following question: What is an isotope? Atoms of the same atomic number but with differing numbers of neutrons in the nucleus 2. Instruct groups to read through the laboratory investigation Handout: Element Investigation. Materials: Newium sample in plastic cup (see Advance Preparation, 3 types of beans, 1 sample per group) electronic balance (1 per group) cups (plastic, 2 per group) page 6 of 16

7 3. Review the Element Investigation with the students, show a sample of Newium, and answer any questions students may have regarding the activity. 4. Inform students that they will be completing a lab report over this activity and should keep detailed data in their science notebooks. 5. Explain that they are going to determine the average atomic mass of Newium based upon the sample s isotopic composition 6. Instruct students to work in groups to complete the investigation. 7. Monitor and assist as needed throughout the investigation. 8. When all students have completed the investigation, instruct student groups to post their calculated average atomic mass for Newium. You may wish to provide a table on the board for this purpose. 9. Guide students to compare results, and facilitate a discussion in which students reflect on why groups may have calculated slightly different values. Ask: How is the average atomic mass of an element calculated? Multiply the amu of each isotope by the abundance factor and sum over the isotopes. Attachments: calculators (1 2 per group) Handout: Element Investigation (1 per group, see Advance Preparation) Instructional Notes: This investigation is designed to model how average atomic mass is calculated from isotopic data. Later in the lesson, you will provide students isotopic composition data from naturally occurring elements. Each student should be provided a different data set. Each student will then create a laboratory report showing the steps necessary to calculate the average atomic mass of each of his/her assigned element as part of the lesson Performance Indicator. Notebooks: Students record data and make calculations in their science notebooks. EXPLORE/EXPLAIN The Electromagnetic Spectrum 1. Distribute a spectroscope to each student or group of students, and have them view several gas spectrum tubes. 2. Call on students to describe the line spectra they observe. Explain the implications of their observations. Relate to the Engage activity conducted at the beginning of the lesson. 3. Introduce/review the electromagnetic spectrum by displaying a chart of the full electromagnetic spectrum. What are examples of electromagnetic radiation? Radio waves, radar, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays, cosmic rays What information is represented on the chart? (Wavelength, frequency) Which has the longest wavelength? (Radio waves) The shortest? (Cosmic rays) Which has the highest frequency? (Cosmic rays) The lowest? (Radio waves) Where is visible light located? (Between infrared and ultraviolet) 4. Discuss wavelength, frequency, and energy. Work sample problems to calculate wavelength, frequency, and energy using Planck s constant and the speed of light. Relate energy to the observations of the line spectra and Bohr model of the atom. 5. Explain Schrodinger s electrons and the quantum mechanical model of the atom. 6. Assign sample practice problems as appropriate from your locallyadopted textbook or other local resources. Suggested Day 3 (continued) Materials: chart of electromagnetic spectrum (see Advance Preparation, 1 per teacher for projection) spectroscopes (1 per student or group) gas spectrum tubes (1 per student or group) spectrum tube power supply (1 per teacher) Instructional Notes: If gas spectrum tubes and a spectrum tube power supply are not available, flame test procedures can be used. An alternative to providing spectroscopes would be to have students build a simple spectroscope. Students are expected to use formulas to solve problems rather than to have a depth of understanding of the principles of quantum mechanics. STAAR Notes: The use of the periodic table to identify and explain the properties of chemical families and periodic trends will be tested as Readiness Standards under Reporting Category 1: Matter and the Periodic Table. page 7 of 16

8 Included in the STAAR Reference Materials is a periodic table of the elements that includes the lanthanide and actinide series. Shown within the table are the name, symbol, atomic number, and atomic mass with mass numbers in parentheses those of the most stable or most common isotopes. The STAAR Reference Materials also include the formula for the speed of light under Atomic Structure and the value for the speed of light under Constants and Conversions. The STAAR Reference Materials also include the formulas for the photon energy and speed of light under Atomic Structure and the values for Planck s constant and the speed of light under Constants and Conversions. Prior grade level notes: Students compare metals, nonmetals, and metalloids using physical properties such as luster, conductivity, or malleability in Grade 6 (6.6A). Students interpret the arrangement of the periodic table, including groups and periods, to explain how properties are used to classify elements in Grade 8 (8.5C). Students explore how different wavelengths of the electromagnetic spectrum, such as light and radio waves, are used to gain information about distances and properties of components in the universe in Grade 8 (8.8C). Notebooks: Students take notes and work sample problems in their science notebooks. ELABORATE/EVALUATE Performance Indicator II History of Atomic Theory Research High School Unit 03 PI 02 Produce a product (such as a timeline, brochure, or poster) that will show the development of the modern model of the atom by identifying scientists and their experiments, conclusions, and contributions. Include the historically important work of Dalton, Thomson, Rutherford, Bohr, and Schrödinger. Standard(s): C.3A, C.3D, C.3F, C.6A ELPS ELPS.c.1C, ELPS.c.4J, ELPS.c.5G 1. Refer to the Teacher Resource: Performance Indicator II Instructions KEY for information on administering this assessment. Suggested Days 4, 5, and 6 Attachments: Handout: History of Atomic Theory (1 per student) Teacher Resource: Performance Indicator II Instructions KEY Instructional Notes: You may want to introduce this project at the beginning of the lesson to allow student groups more time to prepare. Provide books and other resources (Internet) for the students to use for their research. Consider providing a list of available resources in both hard copy and electronic form. page 8 of 16

9 If available in your community, request a museum employee to come on presentation day and provide feedback to students. Notebooks: Students affix the handout and record all research in their science notebooks. EVALUATE Performance Indicator I Atomic Mass Lab Report Suggested Day 7 High School Unit 03 PI 01 In a laboratory report, given the isotopic composition of one or more natural elements, show the steps necessary to calculate the average atomic mass of each of the elements. Standard(s): C.2I, C.6D ELPS ELPS.c.1G, ELPS.c.3C, ELPS.c.5F 1. Refer to the Teacher Resource: Performance Indicator Instructions I KEY for information on administering this assessment. Materials Data sets (isotopic composition data from naturally occurring elements, 1 different set per student, see Advance Preparation) Attachments: Teacher Resource: Performance Indicator I Instructions KEY page 9 of 16

10 Cube Template HS/ Prior to Day 1, create the Number Cubes and Shape Cubes. Create enough cube templates on white cardstock in order to have one of each type of cube per group of four students. Cut out the pattern, fold it into a cube, and secure each with tape. Alternatively, construct larger cubes from cubical boxes. Shading is important so be sure to follow the template precisely. The bottom face of every cube will be blank. Number Cubes: Shape Cubes: Credit: Adair, J. (Designer) (2012) Cube Template. (Graphic). Used with permission. 2012, TESCCC 04/09/13 page 1 of 1

11 Element Investigation HS/ Introduction: Why do some elements in the periodic table have unusual values for their atomic masses, like chlorine at amu? What does it mean when a chemist says that the atoms in a sample of an element are different isotopes of each other? Isotopes are atoms of the same element that differ in atomic mass due to differing numbers of neutrons. For example, there are three different isotopes of hydrogen atoms: hydrogen-1, hydrogen-2, and hydrogen-3. These hydrogen atoms contain 0, 1, and 2 neutrons respectively. In a naturally-occurring element, these isotopes are found in different amounts, expressed as percent abundances. Refer to the table below for isotope examples of the common elements hydrogen and carbon. ISOTOPE PROTONS ELECTRONS NEUTRONS % Abundance SIGNIFICANCE Protium normal hydrogen H-1 Deuterium heavy hydrogen H-2 Tritium trace radioactive hydrogen H-3 Chlorine chlorine Chlorine chlorine Purpose: The following investigation is designed to model how average atomic mass is calculated from isotopic abundance data. You will gather and organize data about the hypothetical element Newium s three isotopes - Firstium, Secondium, and Thirdium. Then, you will calculate each isotopic mass, the abundance of each isotope, and, finally, the average atomic mass of Newium. Definitions: Isotopic mass the average mass of the atoms of a particular isotope Isotopic abundance the percent of the atoms of a particular isotope Average atomic mass the average mass of the atoms of an element Procedure: 1. Copy and complete the following data table in your science notebook. Record the total number of atoms and the number of each type of isotope in your data table. DATA TABLE Isotope Information: Total number of Newium atoms in cup = Isotope Beans (atoms) Mass of Beans (atoms) Firstium Secondium Thirdium Average Mass of one Bean (g) Total Beans 2012 TESCCC 04/09/13 page 1 of 1

12 2. Obtain a sample of Newium in a plastic cup and two more empty cups. HS/ 3. Sort the atoms of Newium into the respective isotopes: Firstium, Secondium, and Thirdium. Decide which beans will represent each isotope. For example: Firstium could be the kidney or red beans. a) Count each of the three isotopes of Newium; record the number and the respective color or type of bean that represents each isotope. b) Determine the total mass of each of the three isotopes; record data. c) Determine the average mass of a single bean (atom) of each isotope; record data. 4. To find the isotopic abundance for each isotope (% of beans), divide the number of beans of one isotope by the total number of beans (Firstium, Secondium, and Thirdium combined) and multiplying by 100%. Record data. 5. Use the formula below to determine the average atomic mass for Newium based on the isotopic abundances and the isotopic masses. FORMULA FOR AVERAGE ATOMIC MASS = (Firstium %) x (mass of one Firstium atom) + (Secondium %) x (mass of one Secondium atom) + (Thirdium %) x (mass of one Thirdium atom) divided by Place your Newium sample back in the plastic cup provided, and return it to your teacher TESCCC 04/09/13 page 1 of 2

13 History of Atomic Theory Research PI II HS/ 1. To assist with the understanding of the structure of the atom, investigate the contributions of the following scientists: Dalton Thomson Rutherford Bohr Schrödinger 2. When you have completed your research, create a product to present the information. Use a format such as a brochure, poster, or timeline (with the intent of the product being used to enhance a science museum exhibit). Your product should include: any experiments that were done by the scientists conclusions from these experiments the impact of the scientists contributions to the understanding of the structure of the atom 2012, TESCCC 04/09/13 page 1 of 1

14 Performance Indicator II Instructions KEY HS/ Performance Indicator Produce a product (such as a timeline, brochure, or poster) that will show the development of the modern model of the atom by identifying scientists and their experiments, conclusions, and contributions. Include the historically important work of Dalton, Thomson, Rutherford, Bohr, and Schrödinger. (C.3A, C.3D, C.3F; C.6A, C.6B) Attachments: Handout: History of Atomic Theory PI (1 per student) Instructional Procedures: 1. Present the logistics of the History of Atomic Theory research project. Distribute a copy of the handout to each student. 2. Students will produce a product (such as a timeline, brochure, or poster) that will show the development of the modern model of the atom by identifying scientists and their experiments, conclusions, and impacts of their contributions. Allow for student voice and choice in format of products. 3. Students should include the historically important work of Dalton, Thomson, Rutherford, Bohr, and Schrödinger. The intended audience for student presentations is a local science museum curator planning a history of the atom exhibit. The visuals created are intended to enhance the display. 4. Allow students to work in groups to conduct research and prepare the products. 5. Define your minimum expectations for the timeline product. You may wish to have groups meet with you to obtain approval prior to research and completion. Include: Dalton s postulates, Thomson s discovery of electron properties, Rutherford s gold foil experiment and nuclear atom, Bohr s experiments with hydrogen spectra and nuclear atom, and Schrödinger s contributions. 6. Student groups now present their product to the class. Classmates may present peer feedback through both warm and cool comments. 7. Warm comments include statements of what they like about the product/presentation. 8. Cool comments are constructive remarks that would make the product/presentation even more compelling. 2012, TESCCC 04/09/13 page 1 of 2

15 Instructional Notes: HS/ You may want to introduce this project at the beginning of the lesson to allow student groups more time to prepare. Provide books and other resources (Internet) for the students to use for their research. Consider providing a list of available resources in both hard copy and electronic form. If available in your community, request a museum employee to come on presentation day and provide feedback to students. 2012, TESCCC 04/09/13 page 2 of 2

16 Performance Indicator I Instructions KEY HS/ Performance Indicator In a laboratory report, given the isotopic composition of one or more natural elements, show the steps necessary to calculate the average atomic mass of each of the elements. (C.2I; C.6D) 1G; 3C; 5F Advance Preparation: Gather appropriate data sets (isotopic composition data from naturally occurring elements) for the Evaluate Performance Indicator. Each student will need a different data set. Isotopic abundances for the Performance Indicator may be found by conducting a browser search for exact masses and isotopic abundances. Materials: Data sets (isotopic composition data from naturally occurring elements, 1 different set per student, see Advance Preparation) Instructional Procedures: 1. Post or project the following information on the board: a) You will be given isotopic composition data for a naturally-occurring element. b) Using this data, you will create and submit a laboratory report showing the steps necessary to calculate the average atomic mass of your assigned element. 2. Present your expectations for the lab report and calculations (see Instructional Notes). 3. Answer any questions students may have regarding the assessment. 4. Monitor and assist as students complete the assessment. Instructional Notes: Each student will create and submit a laboratory report showing the steps necessary to calculate the average atomic mass of his/her assigned element. You may wish to refer to the resource: Creating the Notebook: A Tool for Evaluating Student Work for a sample of a science lab report and rubric. The resource is located in the Instructional Resources section of the website. Students may need to complete the lab report outside of class. Be sure to let them know your expectations. 2012, TESCCC 04/09/13 page 1 of 1