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Flashcards in Radioactivity Deck (19):

What is radioactivity

Went to nucleus is unstable and spontaneously decays emitting radiation and energy.

It is unaffected by
⚡️grinding it up act



🐬helium nucleus, 2n+2p
🐬2+ charge
🐬travel through 2-3cm of air, easily stopped by paper
🐬strongest ionising power
🐬can’t pass through skin, not as dangerous outside body
🐬it will damage cells if it has been breathed in or swallowed



🐬fast electron
🐬negative charge
🐬faster Alpha so greater penetrating powers
🐬travel through 2-3m of air but stopped by aluminium
🐬ionising power in the middle
🐬can penetrate skin + cause damage
🐬0 b



🐬high energy wave
🐬no mass
🐬greatest penetrating powers, travel several m in air
🐬thick block of lead greatly reduces effects
🐬weakest ionising power
🐬can penetrate skin and cause damage



Removal of electron from an atom


Exposure to radiation can cause

🤢loss of hair


Minimise reused ig radioactivity by

👻wearing protective clothing

📏keeping source far away as possible using tongs

⌛️limit exposure time

🎛keep the radioactive material in lead lined container


Background radiation

💤is the activity when all the radioactive sources have been removed.
Mostly comes from natural sources
🌳Radon gas from underground rocks
☄️Cosmic rays from space

Human behaviour also contributes eg
🏥X rays
🏭radioactive waste from nuclear power plants
💣radioactive fallout from nuclear weapon testing


What can be done in areas of high background radiation

Home well ventilated to remove gas

Little can be done about background radiation.


How do living things contribute to radioactivity

Living things absorb radioactive elements from soil and these are passed along the food chain.


What is half life

The time taken for the activity to fall by half


Unit of radioactivity

Becquerel Bq


Why is nuclear radiation dangerous

Ionises atom.
Radioactive emissions cause dangerous ionisations. When this happens in the living cells the genetic materials of a cell is damaged and the cell may becomes cancerous


describe some uses of radioactivity in industry, medicine and agriculture

• radioactive isotopes are used as tracers to find out
what is happening inside an object without the
need to break into the object;

• radioactive isotopes are used in industry to find the
route of underground pipes using a gamma ray emitter, or to control the thickness of metal as it is rolled into thin sheets;

• gamma rays are used in medicine to sterilise plastic objects such as syringes, and different radioactive isotopes are used to monitor the function of organs by injecting a small amount into the bloodstream and detecting the emitted radiation;

• gamma rays are used in agriculture to kill the bacteria on food, prolonging its shelf life;

• alpha radiation is used in the home in smoke alarms.


What should be considered before using radioactive materials

The Half life of a source needs to be considered to ensure the application works but minimal harm is done to the environment


Measuring activity

The number of disintegrations (decays) per second.
Measured using a Gieger muller tube and counter or rate counter


Measuring the approximate range of alpha radiation

✨Please GM tube on a wooden cradle and connect it to the counter

✨ Hold an alpha source directly in front of the window of the tube and slowly increased the distance between the source and the tube. At about 3 cm the counter reading will dramatically fall to that of the background radiation

✨Place a thin piece of paper in contact with the window of the GM tube. Bring the alpha source up to the paper so that the casing off a source touch it. The reading on the counter should now be the same as the background count, showing that the alpha particles cannot penetrate paper.


Measuring the approximate range of beta radiation

✨ place a 1mm piece of aluminium in contact with the window of the GM tube.

✨ Bring the beta source up to the aluminium so that the case off the source touches it.

✨ Reading on the counter it should be significantly above the background count, showing the beta particles come penetrate the aluminium.

✨ repeat the process with different sheets of aluminium increasing the width by a mm at a time. At about 5 mm there should be a significant reduction in the counter rate indicating the approximate range of beta particles in aluminium


Measuring the approximate range of gamma

If the beta particle experiment is repeated with a gamma source there is practically no reduction in the count rate of 5 mm thick piece of aluminium. If the aluminium sheets are replaced with lead it will be found that even school sources will give gamma radiation that can easily penetrate several centimetres of lead.