M2L4 Mastery Half-Life Gizmo-ALL ANSWERS CORRECT-GRADED A+

Name: ______________________________________ Date: ________________________



Student Exploration: Half-life
NCVPS Chemistry Fall 2014
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




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popcorn popping.




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2. If you turn the microwave on for two minutes, is the rate of popping always the same, or




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does it change? Explain. The rate of the popcorn popping is not the same, the shorter




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the time the less popped popcorn you will get
Gizmo Warm-up rs e
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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
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energy. This process, called decay, causes the radioactive
atom to change into a stable daughter atom.
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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 ( ).
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1. What do you see and hear?
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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.
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2. What remains at the end of the decay process? The only remaining thing is daughter
atoms
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3. Is the rate of decay fastest at the beginning, middle, or end of the process? It is fastest
in the beginning




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, Get the Gizmo ready:
Activity A:  Click Reset ( ). Be sure that User chooses
half-life and Random decay are selected.
Decay curves
 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 side of the Gizmo and click Play.

A. What happens to the numbers of radioactive and daughter atoms as the simulation

proceeds? The number of radioactive atoms goes down as the number of

daughter atoms goes up




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B. Do the numbers of radioactive and daughter atoms change at the same rate




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throughout the simulation? Explain. I believe that they are changing at the same




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rate, because one radioactive cell must change in order to become a daughter




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cell, so if radioactive is losing one at the same time that daughter is gaining
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one, then it must be at the same rate
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2. Interpret: How does the Half-life setting affect how quickly the simulated substance decays?
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The higher the half-life the more seconds it will take for all of the radioactive atoms to
become daughter atoms, the lower the half-life the less seconds it will take for daughters
to become radioactive.
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(Activity A continued on next page)
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