Atomic Stability Worksheet-Teacher Answer Key
1. Create a pretend radioactive nucleus for Element 1 including 5 neutrons (N) and 6 protons (P).
2. Demonstrate what happens to Element 1 when the pretend radioactive nucleus emits an alpha
particle and a new element (Element 2) is formed. Then enter the number of neutrons and
protons in the nucleus of Element 2. Students should remove two protons and two neutrons.
What differences do you observe between the number of protons and neutrons in Element 2 and
Element 1? When a radioactive atom releases an alpha particle, the number of protons and
neutrons each decrease by two.
3. Return Element 2 to its original form: Element 1 (5 neutrons and 6 protons). Demonstrate what
happens to Element 1 when it emits a beta particle and a new element (Element 3) is formed.
Then enter the number of neutrons and protons in the nucleus of Element 3. Students should
change a neutron to a proton and an electron (-1). The proton stays in the nucleus and the
electron is released or ejected from the nucleus in the form of beta particles.
What differences do you observe between the number of protons and neutrons in Element 3 and
Element 1? The release of a beta particle decreases the number of neutrons by one and
increases the number of protons by one.
4.	Every element has a different number of protons. What happens to unstable (radioactive) atoms
when they release an alpha or beta particle and the number of protons change? When the
release of energy changes the number of protons in the nucleus, the atoms transform into a
new radioactive element. Radioactive atoms decay and transform into new elements until they
become stable.
5.	Observe the changes in the number of protons and neutrons between the two elements below.
Determine whether the examples show the release of an alpha particle or a beta particle. Circle
the correct answer.
Example 1: Alpha particle. The number of protons and neutrons decrease by two.
Example 2: Beta particle. The number of protons increases by one and the neutrons decrease
by one
Element 1
Element 1
Element 2
Element 1
Element 3
v>EPA
United States
Environmental Protection
Agency
RadTown Radioactive Atom Activity Set	EPA 402-B-19-020
https://www.EPA.gov/RadTown/Activitv-4-Atomic-Stability

-------