Nuclear Decay Gizmo Answer Key

Name: Cassie Cantrell Date: 04-25-2022 Student Exploration: Nuclear Decay Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: alpha particle, atomic number, beta particle, daughter product, gamma ray, isotope, mass number, nuclear decay, positron, radioactive, subatomic particle Prior Knowledge Questions (Do these BEFORE using the Gizmo.) The chart below gives the locations, charges, and approximate masses of three subatomic particles. The approximate mass of each particle is given in universal mass units (u). Particle Proton Neutron Electron Location Nucleus Nucleus Orbitals Charge 1+ 0 1– Approximate mass 1u 1u 0u 1. The mass number of an atom is equal to the sum of protons and neutrons in the nucleus. A helium atom has 2 protons and 2 neutrons. What is the mass number of this atom? 4 2. The atomic number of an element is equal to the number of protons in each atom of the element. All helium atoms have 2 protons. What is the atomic number of helium? 2 Gizmo Warm-up While most atoms are stable, some are radioactive, which means that they have a tendency to undergo spontaneous nuclear decay. The decay of radioactive atoms generally results in the emission of particles and/or energy. Several types of nuclear decay can be explored with the Nuclear Decay Gizmo. On the Gizmo, check that Alpha decay and Uranium are selected. 1. Click Play ( ), and then click Pause ( particle made of? ) when the alpha particle is clearly visible. What is an alpha two protons and two neutrons 2. Click Play and observe. Besides the alpha particle, what else is emitted from the nucleus during alpha decay? a gamma ray Gamma rays are energetic electromagnetic waves; they are often emitted in nuclear decay. Activity A: Alpha decay Get the Gizmo ready: ● Click Reset ( ). ● Check that Alpha decay and Uranium are selected. Question: How does alpha decay change the nucleus of a radioactive atom? 1. Predict: As you observed in the warm-up activity, an alpha particle consists of two protons and two neutrons. How will the emission of an alpha particle affect the following? A. The atomic number of the atom: decrease by two B. The mass number of the atom: decrease by four 2. Calculate: Turn on Write equation. What you see is an equation that shows the original uranium atom on the left. The boxes on the right represent the daughter product—the atom produced by radioactive decay—and the emitted alpha particle. A. In the top left box, write the mass number of the daughter product and press “Enter” on your keyboard. What is this number? 234 B. In the bottom left box, write the atomic number of the daughter product and press “Enter.” What is this number? C. 90 ✏️ Click on the picture below , select ✏️ edit. Enter the mass number and atomic number of the alpha particle, which has the same composition as the nucleus of a helium (He) atom. After filling in the boxes in the Gizmo, write the completed equation below: D. According to your equation, what isotope remains after the alpha decay of uranium-238? (Note: You can look up element symbols on the periodic table.) Th - 234 3. Check: Turn on Show equation, and click Play. The equation will appear at the end of the animation. Was your prediction correct? Yes If not, modify your equation above. 4. Practice: Click Reset, turn off Show equation, and select Polonium. decay of polonium, and then use the Gizmo to check your answer. What isotope remains after the alpha decay of polonium-212? Pb-208 5. Practice: Click Reset, turn off Show equation, and select Radium. decay of radium, and then use the Gizmo to check your answer. What dangerous gas is produced by the decay of radium-226? ✏️Write an equation for the alpha ✏️Write an equation for the alpha Rn-222 6. Practice: Americium-241 is a radioactive isotope used in smoke detectors. alpha decay of Americium-241 below. ✏️Write an equation for the 7. Analyze: In each equation, how is the mass number on the left side of the arrow related to the sum of mass numbers on the right side of the arrow? Is this true for atomic numbers? They are balanced, and atomic numbers are included in this. 8. Summarize: In general, how can you determine the mass number of the daughter product after alpha decay has taken place? How can you determine the atomic number? The original mass number is decreased by 4. By deducting 2 from the original atomic number, you can calculate the new one. 9. Think and discuss: Helium is the second most abundant element in the universe, but it is rare in Earth’s atmosphere. Most of the helium used to fill balloons and blimps must be extracted from Earth’s crust. How do you think this helium formed? The alpha particles released by radioactive isotopes are what create this helium. Get the Gizmo ready: Activity B: ● Click Reset, and turn off Show equation. ● Select Beta decay from the Type of decay menu. ● Check that Carbon is selected. Beta decay Question: How does beta decay change the nucleus of a radioactive atom? 1. Observe: Click Play and watch the animation. A. What happens to the decaying neutron during beta decay? The neutron turns into a proton. B. What is emitted from the nucleus during beta decay? Gamma ray and electron C. What is the mass number and charge of the emitted particle? Mass number: 0 Charge: -1 2. Predict: During beta decay, a neutron is transformed into a proton and an electron (the beta particle), which is emitted. Gamma rays are often emitted during beta decay as well. How will beta decay affect the atomic number and mass number of the atom? The mass number will not change, but the atomic number will rise by one. ✏️ 3. Calculate: Turn on Write equation. Fill in the first set of boxes with the mass number and atomic number of the daughter product and the next set of boxes with the mass number and atomic number of the beta particle. (Note: The atomic number of an electron is -1.) Check your answer by turning on Show equation and clicking Play. Modify your equation if necessary. What isotope is produced by the beta decay of carbon-14? ___N-14______________ ✏️ Fill in the equations for the beta decay of iodine-131 and sodium-24 4. Practice: Turn off Show equation. in the spaces below. Use the Gizmo to check your answers. Activity C: Protons into neutrons Get the Gizmo ready: ● Click Reset, and turn off Show equation. ● Select Positron emission. ● Check that Carbon is selected. Introduction: A positron is a type of antimatter that is equivalent to an electron. If a positron and an electron meet, they will annihilate one another in a burst of gamma rays. Question: How do positron emission and electron capture change an atom? 1. Observe: Click Play and watch the animation. A. What happens to the decaying proton during positron emission? In order to change into a neutron, it emits a positron and a gamma ray. B. What is the mass number and charge of the emitted positron? Mass number: 0 Charge: 1 2. Predict: During positron emission, a proton is transformed into a neutron and a positron, which is emitted. The positron will fly through space until it encounters an electron. How will positron emission affect the atomic number and mass number of the atom? The atomic number will drop by 1, while the mass number stays the same. ✏️ 3. Calculate: Turn on Write equation. Fill in the first set of boxes with the mass number and atomic number of the daughter product and the next set of boxes with the mass number and atomic number of the positron. (Note: The atomic number of a positron is 1.) Check your answer by turning on Show equation and clicking Play. Modify your equation if necessary. What isotope is produced when carbon-11 emits a positron? ✏️ B-11 4. Practice: Turn off Show equation. Fill in the equations for the positron emission of xenon-118 and manganese-50 in the spaces below. Use the Gizmo to check your answers. 5. Observe: Click Reset. Select Electron capture, and make sure Tungsten is selected. Click Play and watch the animation. A. What happened to the proton after absorbing an electron? The interaction of the positive and negative charges resulted in it becoming a neutron. B. What is the mass number and charge of the absorbed electron? Mass number: 0 Charge: -1 6. Predict: During electron capture, an electron is absorbed into the nucleus, causing a proton to transform into a neutron. How will electron capture affect the atomic number and mass number of the atom? The atomic number will decrease by 1, while the mass number remains constant ✏️ 7. Calculate: Note that in this equation the particle is absorbed, rather than emitted. Fill in the first set of boxes with the mass number and atomic number of the absorbed electron. Fill in the last set of boxes with the mass number and atomic number of the daughter product. Turn on Show equation and click Play to check. Modify your equation if necessary. What isotope is produced when tungsten-179 absorbs an electron? Ta-179 ✏️ 8. Practice: Turn off Show equation. Fill in the electron capture equations for gold-195 and neodymium-141 in the spaces below. Use the Gizmo to check your answers. 9. Think and discuss: What do electron capture and positron emission have in common? Both have the same impact on the daughter isotope, resulting in a one-less atomic number and a same mass number.