8.01
Radioactive Decay
Lab
Radioactive Decay
• The nucleus of an atom is the ultimate demonstration of
the balance of forces.
• The electromagnetic force causes all like charges to repel
each other.
• That means that every proton in every nucleus is always
pushing away from every other proton.
• Normally, the strong nuclear force can overcome this
repulsive force, and hold the nucleus together.
Radioactive decay
• What happens when it is not?
– Nuclei that are unstable are said to be radioactive.
– These nuclei get rid of their extra energy by
undergoing radioactive decay
– When the nucleus reorganizes, the extra energy comes
out in the form of high energy light (gamma radiation)
Radioactive Decay
• Not every nucleus will decay at the same time.
Every radioactive isotope has its’ own half-life,
the time for half of the remaining material to
decay.
Radioactive Decay
• Types of decay
Type of Decay
Alpha Decay
Beta Decay
Positron Decay (positive
beta decay)
Electron Capture
What particle is
ejected?
What is the net
change?
Radioactive decay
Sample Problems
Lab Time
• We will divide up into teams for this, and
do the lab in the session.
• You will answer the post lab questions as
part of your conclusion for the lab.
Radioactive Decay
1. Place 200 candies in the shoe box, lettered sides up. The candies will stand for atoms
of a hypothetical radioactive element.
2. Cover the box and shake it vigorously for three seconds. This is one time interval.
3. Remove the lid and take out any candies (atoms) that have that are now showing
lettered sides down. These candies represent the atoms that decayed during the time
interval. Count and record in a data table the number of decayed atoms and the
number of remaining, not decayed, atoms.
4. Continue repeating steps two and three until all atoms have decayed or you have
reached 30 seconds on the data table.
5. Repeat the entire experiment (steps 1–4) a second time and record all data.
Radioactive decay
Radioactive Decay
Run 1