GCSE Physics- P4 Atomic Structure (radiation)

What are sources of background radiation?

Air, cosmic rays, x-rays, radioactive rocks, nuclear industry, nuclear waste, food and drink

What is used to measure radiation?

A gieger-muller tube/counter - it beeps/clicks when radiation is emitted

What is the unit for radiation?

Becquerels (Bq), clicks per second

What is he symbol for radiation?

☢

What are the safety precautions for radiation?

lead-lined box for storage, limited exposure, protective clothing- radiation badge, changes colour when exposed for long period, indirect contact, not pointing material at someone

Range of alpha radiation in the air

less than 5cm

Range of Beta radiation in the air

10-15cm

Range of gamma radiation in the air

more than a metre

What is the nuclear model?

The current model used for atoms

What is radiation?

When isotopes are unstable and have to get rid of their energy

What is radioactive decay?

The emission of an alpha particle, beta particle or gamma ray

What are the different types of radiation?

Alpha, beta and gamma

What is a Alpha particle?

2 protons and 2 neutrons (a helium nuclei)

What happens when there is alpha decay?

atomic number -2, mass number -4

What is a beta particle?

An electron emitted by the nucleus

What is the effect of beta decay?

atomic number +1, mass number unchanged

What is a gamma ray?

an electromagnetic ray from the nucleus of an atom

What happens when there is gamma decay?

No effect on atom

What is the charge of different types of radiation?

Alpha particle= 2+ charge, Beta particle= increased, Gamma particle= no charge

what is a radioisotope?

an atom that can emit radiation

what is an alpha particle also known as?

a helium nuclei

What can an alpha particle be stopped by?

paper, skin

what is a beta particle?

A high energy electron

What can beta particles be stopped by?

aluminium foil

What can gamma rays be stopped by?

reduced by centimetres of lead or metres of concrete

Highest to lowest ionising potential:

alpha, beta, gamma

What is ionisation?

A radioactive particle hitting an electron out of its shell, giving it a charge (anion)

What is irradiation?

When an object is exposed to ionising radiation

What are hazards of ionising radiation?

damage to DNA, kills cells and destroys tissues, makes cells multiply uncontrollably (cancer)

What damage can alpha decay cause?

cannot penetrate skin, not dangerous outside body, if inside body, would kill cells by ionising them and cause damage to DNA.

What damage would beta decay cause?

can penetrate skin, can still cause cancer, but slower than alpha.

What damage can gamma decay cause?

penetrate most + furthest, most damaging

Highest to lowest risk from contamination

Alpha, Beta, Gamma

Highest to lowest risk or irradiation

Gamma, beta, alpha

what is contamination?

When an object emits radiation as it has radiation inside it

How is gamma radiation used?

radioactive tracers, sterilisation of medical equipment, radiotherapy

How can tracers be used to detect pipe leaks?

water contaminated with gamma emitting radioactive isotope with half life of a couple days, contaminated water leaks into ground causing build-up of gamma emissions, Geiger-muller tube used to detect where to dig

How is radiation used in radiotherapy?

destroys targeted cells to stop cancer and other abnormal tissue growth, patients tumour is bombarded with ionising radiation from different angles to not destroy the wrong cells, uses gamma rays

How is radiation used to check blockages in pipes (tracers)?

radioactive isotopes travel through bloodstream, buildup of radiation indicates blockage

How is radiation used to sterilise medical equipment?

equipment blasted with gamma radiation, bacteria killed by gamma radiation and sent back to hospitals

How is radiation used in smoke detectors?

Alpha particles ionises air inside detectors, smoke absorbs alpha radiation, altering the ionisation and completing the circuit, allowing current to pass through and the alarm to trigger.

What is the activity of a radioisotope source known as?

number of unstable atoms that decay per second, clicks per second, Becquerels (Bq)

What is half life?

The average time taken for half the nuclei in a sample of a specific isotope to undergo nuclear decay

what is radiation also known as

nuclear

What do radioactive particles decay to?

an unreactive isotope

hoiw to find the half/time taken to decay?

table with half life, time and activity

How does gamma cameras use radioactive tracers?

patient injected with radioactive solution, gamma cameras detects emission of radiation from solution absorbed by organ.

How are tracers used in radioactive implants?

radioactive rods placed in body, close to cancer cells, beta/gamma isotopes used in the form of small seeds/tiny rods to kill cancerous cells, stopping the cell growth

Benefits of using radiation in medicine:

shows proper function of organs, early detection for cancer, shows extent of cancer in body, can shoe blood supply to heart, shows bone density.

risks of using radiation in medicine:

radiation given internally- risk of ionisation, low doses stay for days, larger does can stay for up to 3 months

Precautions for using radiation in medicine

exposure to small dosage of radiation, patients to be kept away from young children and pregnant women

What is nuclear fission?

splitting a large atomic nuclei to smaller nuclei

What is nuclear fusion?

joining of two small, light nuclei to make a heavy nucleus

advantages of fission

large, reliable amount of energy produced, uranium and plutonium are relatively cheap, no greenhouse gases produced in the production of energy

disadvantages of fission

produces lots of radioactive waste- some with very long half lives, expensive to dispose of waste, risk of major disaster (chernobyl), non renewable- one day no more nuclear fuel

How is radioactive waste disposed of?

it is stored in metal tubes deep under ground

what radioisotopes are used in nuclear fission?

Uranium 235, plutonium 239

Where can nuclear fusion currently be done?

in stars, including the sun.