5.3 Alpha, Beta and Gamma Radiation Flashcards
When isotopes of an element are unstable, what does this mean?
They can undergo radioactive decay, this is where they emit something so that they can change slightly and become more stable
What is meant by a ‘radioactive’ substance?
It consists of unstable isotopes that can decay
What are the 4 types of nuclear radiation?
- Alpha
- Beta
- Gamma
- Neutrons
What are alpha particles made up of?
An alpha particle is 2 neutrons and 2 protons - the same as a helium nucleus.
What is the relative mass and relative charge of alpha particles?
They have a relative mass of 4 - alpha particles have no electrons so they have an overall charge of 2+
How can alpha particles be stopped?
They are relatively large so alpha particles can be easily stopped by collisions with other molecules which means that they can’t penetrate very far in other materials. They can only travel a few cm in the air and are absorbed by a single sheet of paper
Is alpha radiation very ionising or no? and why
Their large size and strong charge makes them very strongly ionising which means they can easily knock electrons off any atoms they collide with
What is a beta particle?
A beta particle is identical to an electron, with virtually no mass and a relative charge of -1
How do beta particles decay?
Strangely, the electrons aren’t emitted from one of the atom’s shells. Instead, one of the atom’s neutrons decays into a proton and an electron. The proton stays in the nucleus but the electron is emitted out at a high speed
How ionising are beta particles and how far do they penetrate?
Because beta particles are very small, they are moderately ionising and they penetrate moderately far into materials. E.g. it would take several metres of air or 5mm of aluminium to stop it
How is gamma radiation emitted from an atom?
After spitting out an alpha or beta particle, the nucleus might need to get rid of some extra energy. It does this by emitting a gamma ray - a type of electromagnetic radiation with a high frequency
What mass and charge does gamma radiation have?
It has no mass and no charge. They just transfer energy, so they dont change the element of the nucleus that emits them
What can gamma rays pass through when they’re emitted by atoms?
As they don’t have any mass or charge, they tend to pass straight through the materials rather than colliding with the atoms. They can penetrate really far into materials before being stopped; they can travel long distances in air and can be stopped by thick sheets of lead/multiple metres of concrete
Is gamma radiation when emitted from atoms very ionising or weakly ionising?
As they have no mass and charge, they can pass through any materials without colliding with atoms; this makes them weakly ionising.
How are neutrons emitted from atoms?
If a nucleus contains a lot of neutrons, it may just through out a neutron
