Understanding Half–Life : Simulating the process of a radioactive material decaying according to the concept of a half-life.
In this activity, students will learn the concept of half-life and how it relates to radioactive material. Students will determine, with a hands-on experiment, the half-life of a radioactive element, "Coinheadsium". Students will create and be able to recognize a graph representing the half-life of a radioactive element.
Context for Use
Activity: Classroom Activity
High School (9-12)
This is a classroom activity
One class period
Radioactive elements change spontaneously through the emission of nuclear radiation, atoms of the element change to produce an atom of a different element by emitting an alpha or beta particle and energy called radioactive decay.
The half-life of a radioactive element is the time it takes for half of a statistically large number of atoms in a sample to decay into something else.
Description and Teaching Materials
After I review the concept of half-life, the students will simulate radioactive decay using a twizzler. Assuming the half-life of the twizzler to be 15 seconds, the students will figure out the length of the twizzler at the end of one half-life and cut it to that length. The students will continue and stop at the end of four half-lives.
In the next activity, the students will investigate the relationship between the passage of time and how many radioactive nuclei decay. They will assume that each heads-up penny represents an atom of the radioactive element "Coinheadsium". Its decay produces a tails-up penny, the element "Cointailsium".
The student groups will be given 100 pennies and a box. Placing all pennies heads up will represent the starting sample of "Coinheadsium". Each shake of the closed box will represent one half-life. During this time a certain number of "Coinheadsium" nuclei will decay to produce "Cointailsium". (that is some pennies will flip over)
The students will be given an activity sheet with the procedure and a table to record their observations. They will make a graph of "atoms surviving" versus "half-lives". They will answer a few post activity questions.
Teaching Notes and Tips
II.A.1 – Structure of matter