Student Exploration: Half-life

Vocabulary: daughter atom, decay, Geiger counter, half-life, isotope, neutron, radiation, radioactive, radiometric dating Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. Have you ever made microwave popcorn? If so, what do you hear while the popcorn is in the microwave? You hear the sound of the microwave, kind of like white noise, and the sound of the popcorn popping. 2. If you turn the microwave on for two minutes, is the rate of popping always the same, or does it change? Explain. The rate of the popcorn popping is not the same, the shorter the time the less popped popcorn you will get Gizmo Warm-up Like an unpopped kernel in the microwave, a radioactive atom can change at any time. Radioactive atoms change by emitting radiation in the form of tiny particles and/or energy. This process, called decay, causes the radioactive atom to change into a stable daughter atom. The Half-life Gizmo™ allows you to observe and measure the decay of a radioactive substance. Be sure the sound is turned on and click Play ( ). 1. What do you see and hear? You see the atoms transforming into daughter atoms and hear a clicking noise Note: The clicking sound you hear comes from a Geiger counter, an instrument that detects the particles and energy emitted by decaying radioactive atoms. 2. What remains at the end of the decay process? The only remaining thing is daughter atoms 3. Is the rate of decay fastest at the beginning, middle, or end of the process? It is fastest in the beginning Get the Gizmo ready: Activity A: • Click Reset ( ). Be sure that User chooses Decay curves half-life and Random decay are selected. • Check that the Half-life is 20 seconds and the Number of atoms is 128. Question: How do we measure the rate of radioactive decay? 1. Observe: Select the BAR CHART on the right s