P7 - Radioactivity 1️⃣✅ Flashcards
What is activity in terms of radioactivity?
The rate of decay/ number of unstable atoms that decay per second in a radioactive source
What is alpha radiation?
Alpha particles, each composed of 2 protons and neutrons, emitted by unstable nuclei
What is an atomic number?
The number of protons (which equals the number of electrons) in an atom.q
What is beta radiation?
Beta particles that are high energy electrons created in, and emitted from unstable nuclei
What is count rate?
The number of counts per second detected by a Geiger counter
What is gamma radiation?
Electromagnetic radiation emitted from unstable nuclei in radioactive substances
What is half-life?
The average time taken for the count rate to fall to half its original value
What is the unit of radioactivity?
Bequerel, Bq
What is an alpha particle?
A particle that consists of 2 protons and neutrons
What is a beta particle?
A particle that consists of high speed electrons
What is gamma decay?
The emission of electromagnetic radiation from an unstable nucleus
What is the charge of alpha?
+2
What is the charge of beta?
-1
What is the charge of gamma?
0
What is alphas symbol/equation for decay?
A (A - 4) 4
X → Y + α
B (B - 2) 2
What is betas symbol/equation for decay?
A A 0
X → Y + β
B (B + 1) -1
What is gammas symbol/equation for decay?
A A 0
X → Y + γ
B B 0
What type of radiation is most dangerous inside the body?
Alpha
What type of radiation is most dangerous outside the body?
Beta
What type of radiation is most dangerous at a distance?
Gamma
What is alphas ionising power?
Alpha has the highest ionising power
What is betas ionising power?
Beta has a high ionising power
What is gammas ionising power?
Gamma has a low ionising power
How far does alpha travel in air?
Alpha travels as few centimetres in air
How far does beta travel in air?
Beta travels around 1m in air
How far does gamma travel in air?
Gamma has a virtually unlimited range in air
What is alpha stopped by?
Alpha is stopped by a sheet of paper & cant get through skin
What is beta stopped by?
Beta is stopped by a few millimetres of aluminium and a thin sheet of lead
What is gamma stopped by?
Gamma is stopped by several millimetres of thick lead or meters of concrete
What is irradiation?
Irradiation is when an object is exposed to nuclear radiation
What is contamination?
Contamination is when atoms of a radioactive materials are on or in an object
How can you stop irradiation?
Irradiation is prevented by shielding, removing, or moving away from the source of radiation
How can you stop contamination?
Contamination can be very difficult to remove
What is background radiation?
Radiation that is around us all the time
What is nuclear fission?
Nuclear fission is when a large unstable nucleus absorbs an extra neutron and splits into 2 smaller nuclei of roughly equal size
What happens during nuclear fission?
The splitting of large and unstable nuclei into 2 smaller nuclei
What is nuclear fusion?
Nuclear fusion is when two light nuclei join to make a heavier one. Some of the mass is converted to energy and transferred as radiation (only happens in stars)
What is an isotope?
An isotope is an atom of the same element with different numbers of neutrons
What is radioactivity?
Radioactivity is when particles are unstable and they give out energy from their nucleus to become more stable
What is ionisation?
Ionisation is removing an electron from an atom
What is radiotherapy?
The use of radioactivity to treat diseases like cancer
How can radiation be used in medical means?
Gamma-emitting tracers are injected or swallowed by a patient, allowing for gamma cameras to create an image showing where the tracer has gone. The half-life of the tracer MUST be short enough so that it will decay shortly after the image is produced to limit the patients radiation dose
Does nuclear fission occur naturally?
No, for it to hapen on its own is very rare so in order for humans to use the energy it generates we have to fire a neutron at the nuclei in order for it to absorb it and split into 2 smaller nuclei
What is meant by a chain reaction in nuclear fission?
That as the 1st nuclei splits into 2 smaller nuclei via the neutron being absorbed those 2 nuclei also absorb a neutron, casuing 2 more to be released from each of the previous nuclei forming a chain reaction
How does a nuclear bomb work?
An uncontrollable chain reaction that releases huge ammounts of energy
How do nuclear reactors not also explode due to chain reactions like nuclear bombs?
They are conrolled using control rods to remove some of the neutrons so that the chain reaction happens much slower and is controlled to control the ammount of energy that is released
