Radioactive Decay Flashcards
(22 cards)
In what order were the following particles discovered?
Electron, Neutron, Proton, Nucleus
- Electron
- Nucleus
- Proton
- Neutron
What happens when a nucleus is unstable?
It decays by emitting radiation.
What does unstable mean?
When a nucleus has too many/few neutrons.
How does an unstable nucleus decay?
By emitting an alpha particle, beta particle or a gamma ray
If the nucleus has too few neutrons it will emit ____.
an alpha particle
How is an alpha particle written?
4
He
2
If the nucleus has too many neutrons, …
a neutron turns into a proton and emits a fast-moving electron, called a beta particle
How is a beta particle written?
0
e
-1
After emitting an alpha or beta particle, the nucleus will emit ___________.
a gamma ray
What is the penetrating power of alpha radiation?
skin/paper
What is the penetrating power of beta radiation?
3mm aluminium foil
What is the penetrating power of gamma radiation?
lead/concrete
Define ‘to ionise’.
To convert an uncharged atom or molecule into a charged particle by adding or removing electrons.
What is the ionising power of alpha radiation?
high
What is the ionising power of beta radiation?
low
What is the ionising power of gamma radiation?
very low
What is the range in air of alpha radiation?
<5cm
What is the range in air of beta radiation?
1m
What is the range in air of gamma radiation?
> 1km
What is ‘half-life’?
The time it takes for half of the number of unstable nuclei in a sample to decay.
What is the unit of radioactivity?
Becquerel (Bq)
What is the activity of a source?
the number of decays per second
