Radioactivity Flashcards
What is the mass number
Number of protons + neutrons
What is the atomic number
Number of protons
What does the atomic number identify
What element it is
What does the mass number identify
The version (isotope) of an element
What is an isotope
An element with the same atomic number (number of protons) but different mass number (number of neutrons)
What stops alpha particles
Thin paper
What stops beta particles
Thin aluminium foil
What stops gamma particles
Thick lead
Which particle has the highest ionising potential
Alpha
Which particle has the lowest ionising potential
Gamma
What particle has the highest penetrating power
Gamma
Which particle has the lowest penetrating power
Alpha
What is ‘activity’
Number of counts (decays/disintegrations) per seconds
What is decay measured in
Becquerals (Bq)
What does a film badge do
Show you what radioactive particle you’ve been exposed to, based on which material has been exposed
What is half life
The time taken for half a radioactive substance to decay
What two things happen when a nucleus decays
Energy decreases
Neutrons decreseases
What does spontaneous mean
When you don’t know when it’s going to happen
Random
No
What is the Alpha composition
Helium nucleus
4
2
Gamma balanced decay equation with
7 Be
4
7 Be. + 0Y
3. 0
Alpha particle
Helium nucleus
4atomic mass, 2 protons
2+ charge and so a big particle and highly ionising
Because of this they only travel a few centimetres in air and are stopped by paper
Beta particle
Fast moving electron from nucleus
Happens when a neutron changes into a proton and electron which is ejected from the nucleus
It only has a single charge so is smaller and relatively less ionising
This means it can travel a bit further in air and is stopped by thin aluminium
Gamma particle
Has no charge and is a very small particle
They have lots of energy, a high frequency and electromagnetic radiation meaning it travels quite far in air and is stopped by a few cms of lead
They are photons and have no charge so rarely interact with anything so travel far
