Half-life Answer Key
Vocabulary: daughter atom, decay, Geiger counter, half-life, isotope, neutron, radiation,
radioactive, radiometric dating
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
[Note: The p
...
Half-life Answer Key
Vocabulary: daughter atom, decay, Geiger counter, half-life, isotope, neutron, radiation,
radioactive, radiometric dating
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
[Note: The purpose of these questions is to activate prior knowledge and get students thinking.
Students are not expected to know the answers to the Prior Knowledge Questions.]
1. Have you ever made microwave popcorn? If so, what do you hear while the popcorn is in
the microwave?
Sample answer: You hear a popping sound as the kernels become popcorn. At first there
are only a few pops, then a lot of pops for a while, and then only a few scattered pops.
2. If you turn the microwave on for two minutes, is the rate of popping always the same, or
does it change? Explain.
Sample answer: The rate of popping is slow at first, then very fast, and then very slow again.
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 red radioactive atoms change to gray daughter atoms. Each time an atom is
transformed there is a bolt of energy and a clicking sound.
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? Daughter atoms remain.
3. Is the rate of decay fastest at the beginning, middle, or end of the process? Beginning
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