P4 - Radioactive Decay & Radioactivity & Half Life Flashcards
What are radioactive materials made up of?
Radioactive materials are made up of atoms with unstable nuclei that naturally decay at random.
What are the three forms of radiation that nuclei can give off?
- Alpha
- Beta
- Gamma
During the decay the nucleus will often change into a new element.
When do you get Gamma radiation?
Gamma radiation happens after alpha and beta emission if the nucleus has some extra energy to get rid of.
- It will emit a Y-ray that has no mass or charge, this means that the atomic and mass numbers don’t change, it is pure energy.
What is an alpha particle, and what are it features?
An alpha particle is a helium nucleus.
- It is made up of two protons
- Two neutrons
- Charge of +2
- Mass of four.
What happens when a nucleus emits and alpha particle?
- The mass number decreases by 4, this is because it loses two protons and two neutrons
- The atomic number decreases by 2, because it has two less protons
- It forms a new element, because the number of protons has changed.
What is a beta particle, and what are its features?
A beta particle is a fast moving electron.
- It has virtually no mass
- A charge of -1
What happens when a nucleus emits a beat particle?
- the mass number doesn’t change, because it has lost a neutron but gained a proton.
- The atomic number increases by 1, because it has one more proton
- It forms a new element, because the number of protons has changed.
What is the correlation between age and radioactivity?
The older a radioactive source is, the less radiation it emits.
- This is because unstable nuclei decay over time.
What is half life?
Half life is the time taken for half of the radioactive nuclei now present, to decay.
What does a short half life mean?
A short half life means the activity falls quickly, because lots of the nuclei decay in a short time,
What does a long half mean?
- A long half life means the activity falls more slowly because most of the nuclei don’t decay for a long time.
