Code Content Expectation Activity C2.4d Compare various wavelengths of light (visible and nonvisible)

Transcription

1 Tracy Haroff Marshall High School Chemistry Teacher Code Content Expectation Activity C2.4d Compare various wavelengths of light (visible and nonvisible) Electromagnetic Spectrum Activity in terms of frequency and relative energy. C2.4a Describe energy changes in flame tests of common elements in terms of the (characteristic) electron transitions. Sparks & Color C2.4b Contrast the mechanism of energy changes and the appearance of absorption and emission Sparks & Color C2.5a Determine the age of materials using the ratio of stable and unstable isotopes of a particular type. Can I Get a Date? C4.8B Describe the atom as mostly empty space with an extremely small, dense nucleus consisting of the protons and neutrons and an electron cloud surrounding the nucleus. C4.8e Write the complete electron configuration of elements in the first four rows of the periodic table. Modeling Rutherford s Gold Foil Experiment Electron Configuration Battleship C4.8f Write kernel structures for main group elements. Electron Configuration Battleship C4.10c Calculate the average atomic mass of an element given the percent abundance and mass of the individual isotopes. Runtium Lab C4.10d Predict which isotope will have the greatest abundance given the possible isotopes for an element and the average atomic mass in the periodic table. Runtium Lab

2 Electromagnetic Spectrum Activity In this activity, we will study the electromagnetic spectrum. Each group will be assigned a portion of the spectrum to explore. The group will design a poster and present information to the class as a presentation. Your poster should include: the name of your portion of the spectrum the wavelength range of your portion of the spectrum in meters the poster should be the length your teacher specifies five appropriate pictures with captions for your portion of the spectrum (examples: how your waves might be used) correct wavelength representation in yarn across the bottom of your poster (Wavelength will be given by your teacher. The height of your wave from trough to peak should be about 4 cm.) The presentation should include: definition of your portion of the spectrum uses of your waves presenting the poster sources of the waves Your grade will be based on the following information: Poster: name of your portion of the spectrum 2 points poster should be the length your teacher specifies 2 points appropriate pictures for your portion of the spectrum with captions (examples: how your waves might be used) 10 points correct wavelength representation in yarn 3 points neatness 5 points works cited page 5 points Presentation: definition of your portion of the spectrum uses of your waves presenting the poster sources of the waves equal speaking time for partners audible speaking voices 5 points 5 points 3 points 3points 5 points 2 points Total Points Portion of Spectrum: 50 points Width of Poster: Wavelength:

3 Group Members: Block: Poster: the name of your portion of the spectrum the poster should be the length your teacher specifies appropriate pictures for your portion of the spectrum (examples: how your waves might be used) correct wavelength representation in yarn neatness /2 points /2 points /3 points /3 points /2 points Presentation: definition of your portion of the spectrum relative wavelengths and frequencies uses of your waves presenting the poster sources of the waves equal speaking time for partners audible speaking voices /3 points /3 points /3 points /3 points /3 points /3 points /2 points Check for Understanding: neatness (computer generated) covers appropriate information answer key provided /2 points /4 points /2 points Total Points /40 points

4 Electromagnetic Spectrum Activity Name: Date: Block: After all presentations, look at the completed electromagnetic spectrum and answer the following questions in complete sentences. 1. As wavelength increases, what happens to frequency? 2. Out of the seven areas of the electromagnetic spectrum, what is the smallest component? 3. Out of the seven areas of the electromagnetic spectrum, what is the largest component? 4. The formula that relates frequency and wavelength is c = λv where c is the speed of light which is 3.0 x 10 8 m/sec, λ is the wavelength in meters and v is the frequency in Hertz. If your favorite radio station is FM, calculate the wavelength of the radio waves. You need to covert from Megahertz to Hertz before you begin the calculation. 5. The wavelength of the radiation used in microwave ovens sold in the United States is meters. Calculate the frequency of the microwave. 6. For each of the seven areas of the electromagnetic spectrum, list a use of those types of waves.

5 Sparks and Color Name: Date: Block: Introduction: In this activity, we will examine three different ways to excite electrons and have them produce visible light. We will see that this visible light has a specific wavelength and color and we will use our knowledge of the visible spectrum to examine the experiments. Section One Materials: rainbow glasses colored pencils spectral graph paper calculator Procedure: 1. View the gas discharge tubes through your rainbow glasses. 2. Using the formula, λ = hc/δe where Δ E is the change in energy in Joules, h is Planck s constant which is x J s, c is the speed of light which is x 10 8 m/s and λ is wavelength in meters, and the energies provided, calculate the wavelength in nanometers. Change in Energy (J) #1 Wavelength (nm) Color 2.86 x J 3.29 x J 3.57 x J 4.73 x J Change in Energy (J) #2 Wavelength (nm) Color 4.09 x J 3.03 x J 4.58 x J Change in Energy (J) #3 Wavelength (nm) Color 3.64 x J 3.38 x J 4.45 x J 2.98 x J 3. Using your spectral graph paper and colored pencils, draw the line emission spectrum for each unknown. 4. As you view the gas discharge tubes the second time, match each unknown to the correct element.

6 Section Two Materials: pliers 2 Wint O Green Livesavers sandwich bag Procedure: 1. Place lifesaver in pliers so that you are ready to crush it. 2. Place pliers with lifesaver into sandwich bag. The sandwich bag will collect the pieces so that you can use the same lifesaver to repeat the experiment. 3. With the lights out, crush the lifesaver. 4. Repeat experiment six to eight times. Record observations. Observations: Section Three Materials: Bunsen burner wooden sticks soaked in various salts matches Procedure: 1. Turn on Bunsen burner and adjust the flame to show the light blue inner cone. 2. Place the wooden stick into the flame for approximately 30 to 60 seconds or until a color change in the flame occurs. Do not burn the stick! Repeat each solution three times. 3. Record observations for each solution. Observations:

7 Questions: 1. What type of energy causes the electrons to become excited in the gas discharge tube? 2. Looking at your spectral graphs and the energies, explain how wavelength and frequency are related. 3. What color has higher energy wavelengths? What color has lower energy wavelengths? 4. What causes the color of the tube? 5. What type of energy causes the electrons to become excited in the lifesaver? 6. When you see the color, what is happening in the atom s structure? 7. What type of energy causes the electrons to become excited in the flame tests? 8. Why is each solution a different color? 9. How could this be used to test an unknown solution?

8 Spectral Graph Paper

9 Name Hour Can I Get a Date? Using the ratio of stable to unstable isotopes to determine age. In this lab, we will use half-life and the ratio of stable to unstable isotopes to determine the age of rocks. Some elements have radioactive isotopes that are unstable and will undergo decay. Decay happens when the radioactive nucleus emits protons, neutrons or both. This will change the identity of the isotope and sometimes changes the mass number. Half-life is the time required for half of a radioactive sample to decay. If you can measure the number of half-lives that has occurred and the half-life of a particular isotope is known, the age of the material can be determined. Many igneous rocks contain trace amounts of radioactive uranium-235. All uranium-235 isotopes have a 50% chance of decay. During 704 million years, half of the uranium-235 atoms that existed at the beginning will decay to lead-207. This time period is the half-life of radioactive uranium-235. In part one, we will be modeling radioactive decay and graphing the results. In part two, we will be using the half-life of uranium-235 to determine the age of rocks. Part One Using m&ms to model decay 1. Wash hands. 2. Count out 100 m&ms and spread out on desk with m side down. This represents the radioactive isotope before decay. Record at trial 0, 100 radioactive isotopes. 3. Place all m&ms in cup, shake and pour out onto desk. 4. When an m&m lands with the m side up, the isotope has decayed. Remove all m&ms that have decayed. 5. Count the number of radioactive isotopes remaining. Record data in data table below. 6. Repeat 8 times. Trial Number of radioactive isotopes Class Average

10 7. Graph your results with half-life (trial) on the x-axis and number of radioactive isotopes on the y-axis. 8. Connect the dots with a smooth curve. 9. On the same set of axes and with a different pencil color, graph the class average data and connect with a smooth curve. 10. On the same set of axes and with a third color, graph the following points: (0,100), (1,50), (2,25), (3,12.5), (4,6.25), (5,3.13), (6,1.57), (7,0.88), (8,0.44). Connect the dots with a smooth curve. This represents the theoretical half-life of the m&ms. Part Two - Use the half-life of uranium-235 to determine the age of rocks. 1. Obtain a set of cards and a time card. 2. Place all cards on the desk with uranium-235 facing up. 3. When the teacher calls time, flip over half of the uranium-235 cards. 4. If your time card is a two minute time card, do not flip any more cards and record data in the data table. 5. If your time card is a 4, 6, 8 or 10 minute card, flip over half of the remaining uranium- 235 cards. 6. If your time card is a four minute time card, do not flip any more cards and record data in the data table. 7. If your time card is a 6, 8 or 10 minute card, flip over half of the remaining uranium-235 cards. 8. If your time card is a six minute time card, do not flip any more cards and record data in the data table. 9. If your time card is an 8 or 10 minute card, flip over half of the remaining uranium-235 cards. 10. If your time card is an eight minute time card, do not flip any more cards and record data in the data table. 11. If your time card is a 10 minute card, flip over half of the remaining uranium-235 cards. 12. If your time card is a ten minute time card, do not flip any more cards and record data in the data table. 13. Turn in your time cards to your teacher. 14. As directed by your teacher, move to a different group s table. 15. Examine the cards on the table and record data. 16. Repeat steps 14 & 15 until all groups data have been recorded.

11 Group Color Number of Lead-207 Number of Uranium-235 Number of Half-lives Age in millions of years Ratio of Stable to Unstable Isotopes Questions for Part One 1. Looking at the graph, how does your data compare to the class average? 2. Looking at the graph, how does your data compare to the theoretical half-life of m&ms? 3. Explain the concept of half-life using a different analogy. 4. Phosphorus-32 is used to treat a certain form of leukemia. Starting with 10 milligrams of phosphorus-32, how many milligrams would be left after 57 days? The half-life of phosphorus-32 is 14.3 days.

12 Questions for Part Two 1. How did you figure out the number of half-lives of each group s sample? 2. How did you calculate the age of each group s sample? 3. a. What is the ratio of stable to unstable isotopes after 1 half-life? b. What is the ratio of stable to unstable isotopes after 2 half-lives? c. What is the ratio of stable to unstable isotopes after 3 half-lives? 4. A rock sample contains 20 milligrams of U-235 and 60 milligrams of Pb-207. What is the age of the rock sample? 5. Radioactive carbon-14 is used to date animal and plant life and decays into nitrogen-14. The half-life of carbon-14 is 5,715 years. If a bone contains 26 micrograms of the stable isotope and 26 micrograms of the unstable isotope, how old is the bone? 6. In minerals, radioactive potassium-40 decays into argon-40. K-40 has a half-life of 1.28 billion years. The age of the mineral was determined to be 3.84 billion years. What is the ratio of the stable isotope to the unstable isotope? 7. Do you think the ratio of stable to unstable isotopes that corresponds to each half-life remains the same for any type of isotope?

13 Modeling Rutherford s Gold Foil Experiment 1. What does the hula hoop represent in Rutherford s Gold Foil experiment? 2. What does the Styrofoam ball represent in Rutherford s Gold Foil experiment? 3. What does the crumpled paper represent in Rutherford s Golf Foil experiment? 4. What happens to most of the crumpled paper? 5. What happens to a few of the crumpled papers? 6. What did Rutherford discover about the structure of the atom?

14 Electron Configuration Battleship You will get 1 boat per orbital block as follows: S block 1 boat = 1 square P block 1 boat = 2 squares D block 1 boat = 3 squares F block 1 boat = 4 squares The blocks that make up your boats must be adjacent to one another. Rules of Battleship apply although I always alternate play even if one person gets a hit. Each student pairs with another and they take turns calling out electron configurations to each other. When all the squares to a boat have been hit, that boat is sunk. The first person to sink all his opponent s boats wins. Variation: Play two rounds, one using the full electron configurations and then the second using noble gas configurations.

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16 Runtium Lab Purpose: The purpose of this lab is to model how the average atomic mass on the periodic table is calculated for an element. In our lab, we are using the element runtium. You will receive a sample of the element; it has 5 isotopes (5 different colored candies). What is an isotope of an atom? Average Atomic Mass = (Mass of Isotope 1 x % Abundance in decimal form of Isotope 1) + (Mass of Isotope 2 x % Abundance in decimal form of Isotope 2) + (Mass of Isotope 3 x % Abundance in decimal form of Isotope 3) + Mass The mass of the isotope you will determine by massing one individual isotope (one individual piece of candy). % Abundance The % Abundance will be determined by taking the number of one isotope and dividing by the total number in the sample and multiplying by one hundred. (example: You have 8 bananas / 16 runts total =.5 x 100 = 50% bananas) Average Atomic Mass This will be calculated by plugging in the mass and % abundance into the formula above. This represents the mass that would be on the periodic table if runtium with its 5 isotopes was a real element. Data Table: Color Mass (g) Percent Abundance Show work for Average Atomic Mass, include units:

17 Questions: What was your calculated runtium average atomic mass? What subatomic particle is the same in all isotopes of one element? What subatomic particle is different in all isotopes of one element? By changing that one particle, what does that change for that isotope? Find the average atomic mass for the following elements showing work below: Isotope Mass % Abundance Magnesium g Magnesium g Magnesium g Isotope Mass % Abundance Boron g 19.9 Boron g 80.1 Strontium has 4 known isotopes: strontium-84, strontium-86, strontium-87 and strontium- 88. Using the known average atomic mass of strontium, predict which isotope has the highest percent abundance. Indium has two isotopes, indium-113 and indium-115. Using the known average atomic mass of indium, predict which isotope has the highest percent abundance.