1. Write nuclear decay equations
Learning Objective
To be able to:
Write nuclear decay equations
Key Words:
Decay, alpha, beta, gamma

2. Nuclear Decay Equations
Wednesday, 22 May 2019
Nuclear Decay Equations
Date and title in books. You need a pen, pencil & ruler.
Starter Activity – 5 minutes Exam question

3. Identify the structure of an alpha particle and a beta particle
Target 1-9
Identify the structure of an alpha particle and a beta particle
(F/H)
Target 4-9
Complete decay equations to identify the type of decay (e.g. alpha or beta)
(H)
Target 5-9
Write full decay equations, when given the element at the start and end.
Extension: Application of Knowledge
Target 8/9
Explain why gamma radiation is emitted and why it doesn’t change the mass number or atomic number
Learning Outcomes

4. What is radioactive decay?
Boardworks GCSE Science: Physics
Radioactivity
What is radioactive decay?
Teacher notes
This activity, summarising the three types of radiation, could be used to introduce the topic of radiation, as a plenary exercise or as a revision exercise.

5. Alpha decay
An alpha particle consists of two protons and two neutrons. It is the same as a helium nucleus.
When an atom’s nucleus decays and releases an alpha particle, it loses two protons and two neutrons.
mass number decreases by 4
238 92 U
234 90 Th 2 4 + α
atomic number decreases by 2
The number of protons has changed, so the decayed atom has changed into a new element.

6. Beta decay
An beta particle consists of a high energy electron, which is emitted by the nucleus of the decaying atom.
When an atom’s nucleus decays and releases a beta particle, a neutron turns into a proton, which stays in the nucleus, and a high energy electron, which is emitted.
mass number remains the same 14 6 C 14 7 N + β
atomic number increases by 1
The decayed atom has gained a proton and so has changed into a new element.

7. The nickel does not change into a new element.
Gamma decay
Gamma radiation is a form of electromagnetic radiation, not a type of particle.
When an atom’s nucleus decays and emits gamma radiation, there is no change to the make-up of the nucleus and so a new element is not formed.
Gamma rays are usually emitted with alpha or beta particles. For example, cobalt-60 decays releasing a beta particle. The nickel formed is not stable and so emits gamma radiation.
Teacher notes
The ‘*’ symbol next to the nickel in the middle of the equation indicates that the nickel is still unstable and needs to release more radioactivity to become stable. 60 27 Co 60 28
Ni* β + 60 28 Ni + 
The nickel does not change into a new element.