Radioactivity Flashcards
Name the subatomic particles in a atom and their masses
Proton (1+)
Neutron (0)
Electron (1-)
What is an isotope?
Atoms with the same number of protons but different number of neutrons
Explain when electrons get ‘exited’
Electrons can get exicted to higher energy levels
An inner electron can move up to higher energy level if it absorbs electromagnectic radiation with the right amount of energy
When it does move up it moves to an empty or partially filled shell.
What does an electron being ionised mean?
If an outer electron absorbs radiation with enough energy it can move so far that it leaves the atom.
It is now a free electron said to be ionised
What is ionising radiation?
Any radiation that can knock electrons from shells
What is radioactive decay?
When elements only have one or two stable isotopes and the other unstable isotopes tend to decay into other elements and give out radiation as they try become more stable
Describe alpha particles
Alpha particles are like helium nuclei
Alpha radiation is when an alpha particle (α) is emitted from the nucleus
An α particle is two neutrons and two protons
They don’t penetrate very far into materials and are stopped quickly, they can only travel a few cm in air and are absorbed by a thin sheet of paper
Because of this they are strongly ionising
They have a 2+ charge and are relatively large
Describe beta particle (β-)
A beta-minus particle (β-) is simply a fast moving electron released by the nucleus. They have virtually no mass and a relative charge of -1
Moderately ionising
Have a range in air of a few metres and are absorbed by a sheet of aluminium (aouund 5mm thick)
Describe a beta particle (β+)
A beta-plus particle is a fast moving positron. The positron is the antiparticle of the electron. This just means it has exactly the same mass as the electron but a positive (1+) charge
They are both moderately ionising
Positrons have a smaller range because when they hit an electron the two destroy each other and produce gamma rays
