Anna Margaret Loftus - Nuclear Decay Gizmo (1)

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). 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? 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? 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 ( ) when the alpha particle is clearly visible. What is an alpha 2. Click Play and observe. Besides the alpha particle, what else is emitted from the nucleus during alpha Gamma rays are energetic electromagnetic waves; they are often emitted in nuclear decay. Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved Name: Anna Margaret Loftus Date: 10/2/20 Particle Location Charge Approximate mass Proton Nucleus 1 + 1 u Neutron Nucleus 0 1 u Electron Orbitals 1 – 0 u The mass number is 4 u. The atomic number of helium is 2. particle made of? 2 protons and 2 neutrons decay? Gamma Rays 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? 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 B. In the bottom left box, write the atomic number of the daughter product and press “Enter.” What is C. 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.) 3. Check: Turn on Show equation, and click Play. The equation will appear at the end of the animation. Was Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved Activity A: Alpha decay Get the Gizmo ready: ● Click Reset ( ). ● Check that Alpha decay and Uranium are selected. A. The atomic number of the atom: Will decrease B. The mass number of the atom: Will decrease keyboard. What is this number? 234 this number? 90 Thorium-234 your prediction correct? Yes If not, modify your equation above. 4. Practice: Click Reset, turn off Show equation, and select Polonium. Write an equation for the alpha decay of polonium, and then use the Gizmo to check your answer. 5. Practice: Click Reset, turn off Show equation, and select Radium. Write an equation for the alpha decay of radium, and then use the Gizmo to check your answer. 6. Practice: Americium-241 is a radioactive isotope used in smoke detectors. Write an equation for the alpha decay of Americium-241 below. 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? 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? 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? Reproduction for educational use only. Public sharing or posting prohibited. © 2020 ExploreLearning™ All rights reserved What isotope remains after the alpha decay of polonium-212? Lead-208 What dangerous gas is produced by the decay of radium-226? Radon The mass number of the reactants is less than that of the mass number of the products. This is also true for atomic numbers, The daughter product is 4 less than the mass number and the daughter product is 2 less than the atomic number. The Helium was formed by Alpha Decay