Name: Caroline Sobolowski Date: 1/1/17

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? Yes, I hear the kernels popping in the bag.

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 popping is not always the same because when you first put

the bag of popcorn in and start the microwave, there is not a lot of popping, but when the

contents of the bag begin to heat up, the popping increases. By the end of the cooking

session, all of the kernels should be popped so there is no more popping.

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? There is a static sort of popping sound as the atoms turn

from red to blueish gray.

Note: The clicking sound you hear comes from a Geiger counter, an instrument that detects

the particles and energy emitted by decaying radioactive atoms.

This study source was downloaded by 100000793680026 from qwivy.com on 06-25-2021 06:12:18 GMT -05:00

https://www.qwivy.com/file/18657578/Half-lifeGizmo/

This study resource was

shared via qwivy.com

 1 / 2

2. What remains at the end of the decay process? Daughter Atoms

3. Is the rate of decay fastest at the beginning, middle, or end of the process? The rate of

decay is fastest near the beginning.

Activity A:

Decay curves

Get the Gizmo ready:

● Click Reset ( ). Be sure that User chooses

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 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 decreases until they reach zero

and the number of daughter atoms increases.

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

throughout the simulation? Explain. No, the numbers of daughter atoms increase

steadily while towards the end of the reaction, the radioactive atoms take

longer to disappear.

2. Experiment: Click Reset, and select the GRAPH tab. Run a simulation with the Half-life set

to 5 seconds, and then run another simulation with the Half-life set to 35 seconds. Sketch

each resulting decay curve graph in the spaces below.

This study source was downloaded by 100000793680026 from qwivy.com on 06-25-2021 06:12:18 GMT -05:00

https://www.qwivy.com/file/18657578/Half-lifeGizmo/

This study resource was

shared via qwivy.com Powered by qwivy(www.qwivy.org)

 2 / 2