Radiation and Half Life Flashcards
What is the central part of an atom called?
The nucleus
What do electrons do around the central part of an atom?
They orbit the nucleus
What mass and charge does a proton have?
Charge of +1 and mass of 1
What mass and charge does a neutron have?
No charge and a mass of 1
What mass and charge does an electron have?
Charge of -1 and a negligible mass/0
What is the top number of an element?
The atomic mass number (Nucleon number)
What can you work out from the top number of an element?
The number of protons
The number of electrons
What is the bottom number of an element?
The atomic number (Proton number)
What can you work out from the bottom number of an element?
The sum of protons and neutrons
How do you work out the number of protons/electrons?
Look at the atomic mass number
How do you work out the number of neutrons?
Atomic mass number - atomic number
What are isotopes?
Isotopes have the same number of protons but different number of neutrons. For elements that have isotopes the atomic mass number/nucleon number can be different. However, the atomic number must be the same.
What does a radioactive atom mean?
The nucleus of the atom is unstable due to an imbalance of protons and neutrons.
What are alpha particles
They are helium nuclei (2 protons and 2 neutrons)
How ionising are alpha particles?
They are the most ionising therefore they cause the most harm
How fast are alpha particles?
They are the slowest and least penetrating type of nuclear radiation.
How can alpha particles be absorbed?
By a thin sheet of paper
What charge do alpha particles have?
A charge of 2+
What are beta particles?
High-energy electrons
How ionising are beta particles?
Medium ionising ability
How can beta particles be absorbed?
By a few millimeters of aluminium
What charge do beta particles have?
A charge of -1
What can beta particles penetrate through?
Paper
What are gamma waves?
High-energy electromagnetic waves
How penetrating are gamma rays?
Most penetrating and are able to travel through aluminium and paper
How ionising are gamma rays?
Least ionising and cause the least harm to living cells in the body
How can gamma rays be absorbed?
Absorbed mostly by a few cm of lead
How fast do gamma rays travel?
At the speed of light (3x10⁸m/s)
How does alpha decay work?
The nucleus emits an alpha particle losing 4 nucleons (2 protons and 2 neutrons) forming …
What is background radiation?
The low level ionising radiation that is in our environment all the time from natural and man-made sources
How does beta decay work?
The nucleus emits a beta particle (electron). The nucleon number stays the same but the proton number goes up by one forming …
Where does most of the background radiation come from?
Naturally occuring sources, primarily from rock, the ground and space
Where does the most of artificial background radiation come from?
Medical sources as a result of medical and dental examinations using X-rays
Is the radiation emitted by any source consistent?
No, it’s totally random
How can you measure radiation accurately?
Measure over a long period of time or calculating an average
What is used to measure radiation?
A geiger counter
What happens to high level nuclear waste?
It’s stored temporarily in water, surrounded by lots of concrete and lead shielding while it cools. The radiation is absorbed by the water, concrete and lead and stored deep underground.
What happens to intermediate level waste?
It can be disposed of by mixing it with concrete in a large steel disposable dum which is then buried.
What happens to low level waste?
Can be disposed of in landfill by surrounding it in concrete in large disposable drums
What is the half life?
The time it takes for the number of nuclei of that element to halve or the time it takes for the count-rate of radioactive radiation to halve
What type of process is radioactive decay?
It’s a random process
How can you estimate the half life?
Measure over a long period of time and do repeat readings.
What curves can be used to show the half life?
Decay curves
What does the uses of radioactive material depend upon?
Half-life, penetrating power and ionising power
How can measuring the thickness of paper be done using radiation?
Beams of beta radiation can monitor thickness and the detector will pick up a constant level of radiation. Any variation will mean the level of radiation picked up will differ
How can you use radiation for sterilisation?
Gamma radiation can be used to kill microbes and sterile medical equipment.
How can you use radiation for medical tracers?
Radioactive material is injected into the body and makes its way to the place and emits gamma rays which can be detected outside the body. Short half lives are used
How can you use radiation for radiotherapy?
The use of radioactive materials to kill affected (usually cancerous) cells. Beta radiation or alpha radiation is used as this has a short range in flesh so that it only kills the cancerous cells. The half life is usually a few days
How can you use radiation for carbon dating?
Carbon 14 is a naturally occurring radioactive isotope of carbon with a half life of 5730 years. Living plants and animals absorb C-14 when alive but stop when they die. Therefore isotope decay takes place
What type of emitter is carbon 14?
Beta
