Lesson 2: Radioactive decay/ Radiation Flashcards
What happens when an isotope has an unstable nucleus?
- To become stable, the nucleus gives out radiation.
- This is known as radioactive decay.
What is meant by radioactive decay being a “random” process?
- Scientists cannot predict when a nucleus will decay.
What is meant by “activity?”
- Activity is the rate at which a source of unstable nuclei decays.
What is activity measured in?
- Becquerels (Bq)
What is 1Bq equivalent to?
- 1 decay per second.
What piece of appartus do you use to measure the activity of a radioactive source?
- Geiger muller tube.
What is the count- rate?
- The count- rate is the number of decays recorded each second by a detector.
not the same as activity because of backgroud radiation
What are the different types of nuclear radiation that can be released from an unstable nucleus?
- Alpha particle α
- a beta particle (β)
- a gamma ray (γ)
- a neutron (n).
What is an alpha particle?
an alpha particle (α) – this consists of two neutrons and two protons,it is the same as a helium nucleus
What is a beta particle?
a beta particle (β) – a high speed electron ejected from the nucleus as a neutron turns into a proton
What is a gamma ray?
- a gamma ray (γ) – electromagnetic radiation from the nucleus
What are the properties of alpha radiation?
- Range in air: 5cm
- Penetrating power: can be stopped with single sheet of paper.
- Ionising power: Very strongly ionising
What does “range in air” mean?
- Range in air means how far different types of radiaition can travel before colliding with air particles and stopping.
What is meant by “ionising power?”
- When radiation collides with atoms, that can cause the atom to lose electrons and form ions.
- How many ions atoms form when radiation hits the material depends on ionising power.
What are the properties of Beta radiation?
- Range in air: 15cm
- Penetrating power: stop with a few mm of aluminum.
- Ionising power: quite strongly ionising.
