# Learning Exercise

Course: Chemistry
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Halfway down the web page is a wonderful applet depicting Radioactive Decay. see more

#### Exercise

Group Members___________________________________________________________________
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Instructions:

1) The pennies represent the atoms in a sample of your radioactive isotope.
2) Seal the container and turn it 4-6 times. This represents one half-life of
3) Spread the pennies out on the table. Remove all the pennies that are tails.
4) Count the number of remaining pennies (heads) and record the number in the
data table.
5) Put the remaining pennies that were heads back into the container and repeat
the steps until your data table is full.

Half-life Pennies

0 100 0

1

2

3

4

5

On graph paper provided, graph pennies vs time period. Plot all data and
connect them with the best fit line.

Group Questions

1) Francium 220 has a half-life of 27.5 seconds. How much time will elapse
after 4 half-life periods?

2) If you have 1600 Francium-220 atoms now, how many will you have left after
82.5 seconds?

3) What does the shaking of the pennies represent in terms of radioactive decay?

4) What do the pennies that were tails in the lab represent?

5) Carbon 14 has been used in a process called carbon dating to figure out the
age of things, why do you think carbon 14 is useful for that? Do you think it
has a half-life that is a few seconds, days, years, decades or more?

See Decay Lesson