Radioactivity Flashcards
What is the atomic (Proton) number?
Number of protons in a nucleus
What is mass (nucleon) number?
Number of proton and neutrons in a nucleus
3 types of radiation are…
Alpha and beta particles
Gamma radiation
What makes a nucleus unstable?
More neutrons than protons
What word describes the way a radioisotope decays?
Random
All types of radiation are capable of ….
Ionisation
Describe alpha particles..
2 proton 2 neutrons
helium nucleus
highly ionising
low penetrating power
stopped by 5cm of air or paper
Describe beta particles …
Very fast electron
medium ionising power
medium penetrating power
stopped by mm of aluminium
Describe gamma….
very high frequency electromagnetic radiation
low ionising power
high penetrating power
stopped by thick lead or metres of concrete
Why is alpha highly ionising?
large mass
2+ charge
What do you use to detect radiation?
GM tube and counter
photographic film
Sources of background radiation…
cosmic rays
rocks
food
nuclear waste
Unit of activity is …
Becquerels (Bq)
Define half life
Time taken for half the radioactive nuclei to decay.
Time taken for activity to fall by half
In an experiment to measure activity, how do you deal with background radiation?
measure background before and after the experiment, take a average and subtract it from all readings
Uses of radioactivity
treating cancer
sterilising medical equipment
medical tracers
industry tracers
dating articles
What is the difference between contamination and radiation?
Contamination: radioactive material enters the body
Irradiation: radiation passed through
Dangers of radiation
mutations in living organisms
damage cells and tissues
problems with disposing of radioactive waste
What is fission?
Neutron splits a heavy, unstable nuclei, producing 2 daughter nuclei and more neutrons, releasing energy
What is fusion?
Two light nuclei join to make one heaver one and release Kinetic energy. Energy comes from a loss of mass during fusion
2 conditions needs for fusion
high temps
high pressure
What is a chain reaction?
Each fission produces more neutrons which go on to split more nuclei and numbers and energy released build up very quickly
What are control rods?
Used in a nuclear fission reactor to absorb excess neutrons and limit fission
What is a moderator?
Slows down neutrons so they can be absorbed by the nuclei to split it
What is shielding?
Outer layer of thick concrete and lead to ensure radiation in contained in a nuclear reactor
Where does fusion happen naturally?
in the stars
Why can’t fusion happen at low temps and pressures?
Nuclei are positively charged and so would repel due to electrostatic repulsion
