This document discusses nuclear reactions and balancing nuclear equations. It defines activity as the number of decays per second, with the unit of activity being the Becquerel. It then reviews the properties of alpha, beta, and gamma radiation, including their nature, sources, ionizing power, penetration, and typical ranges in air. Examples are given of balancing nuclear equations by identifying the particle emitted or nucleus formed during radioactive decay processes.

1. FUNDAMENTAL Physics – Atomic Physics: 7.2 Nuclear Reactions
Nuclear Reactions
Learning Objectives
• I know the definition of Activity and the unit
• I can complete balanced nuclear equations
Activity
Activity is the number of decays per second or the number of radioactive
particles emitted per second. The unit of Activity is the Becquerel (Bq). One
Becquerel is one decay per second.
Balancing Nuclear Equations
Let’s review the nature of Alpha, Beta and Gamma radiation:
Name Symbol Nature Sources Ionising
Power
Penetratio
n
Stopped
by
Range
in air
Alpha α
Helium
Nucleus
4
He2+
Larger
nuclei
Eg.
208
Po
High Low paper 2-3cm
Beta β
An
electron
-1β-1
smaller
nuclei
eg. 40
K
Medium Medium
1-2cm
of Al
Few
feet
Gamma γ
An EM
wave. A
packet of
energy
called a
PHOTON.
Eg. 99
Tc
low high
Several
inches
of lead
kms
Eg1. Americium-241 decays to Neptunium-237. What particle is emitted?
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2. FUNDAMENTAL Physics – Atomic Physics: 7.2 Nuclear Reactions
Particle x is an .....alpha...... particle.
Eg2. Polonium-208 is an alpha source. What does it decay into?
Nucleus x is ....Pb......
2
241
Am → Np + x
237
9395
4
2
208
9 Po → x + α
204
8284
4
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