25 - Radioactivity Flashcards
What is alpha radiation?
Positively charged particles.
2e
(Helium nucleus)
What is beta radiation?
Fast moving electrons or positrons.
+e or -e
What is gamma radiation?
High energy photons with wavelength < 10⁻¹³m
No charge
How can we distinguish between types of radiation using an electric field?
- Alpha particles are deflected a small amount in one direction due to their larger mass
- Beta particles are deflected the most on both directions as they can be either positive or negative
- Gamma photons are not deflected and pass straight through
Compare the range of the three types of radiation.
- Alpha - short range as large and heavy
- Beta - longer range about a metre
- Gamma -very long range,
How can you stop the three different types of radiation?
Alpha - piece of paper
Beta - thin sheet of aluminium
Gamma - a few centimetres of lead
Compare the ionisation of the three types of radiation.
Alpha - extremely ionising
Beta - less ionising
Gamma - even less ionising
Describe alpha decay.
Nucleus emits an alpha particle.
Nucleon number decreases by 4 (2n, 2p)
Proton number decreases by 2 (2p)
Energy also released.
Why do nuclei go through beta minus decay?
If they have too many neutrons.
What decays in beta minus decay?
A neutron into a proton.
What decays in beta plus decay?
A proton into a neutron.
Why do nuclei go through beta plus decay?>
Because they have too many protons.
What is emitted in gamma decay?
A gamma photon.
When does gamma decay occur?
When a nucleus has extra energy left over after beta or alpha decay.
What must balance in a decay equation?
The nucleon and proton numbers.
