Nuclear radiation

What is the radius of an atom?

1 x 10^-10 metres = 0.1 nanometers

What is the radius of a nucleus?

1x10^-14 metres

Isotope

Atoms of the same element that have different numbers of neutrons

Which types of iodising radiation are spat out during radioactive decay

alpha, beta, gamma radiation (may release neutrons)

What is an alpha particle?

2 proton and 2 neutrons (helium nucleus)

How penetrating are alpha particles?

Not very penetrating; they only travel a few centimeters in air.

Why are alpha particles highly ionising?

They are highly ionising due to their size.

What can absorb alpha particles?

Alpha particles are absorbed by paper.

What is a beta particle?

A fast moving electron (no mass) (charge of -1)

How penetrating are beta particles?

Moderately penetrating, have a range of a few metres in the air

How ionising are beta particles?

Moderately ionising (less than alpha, more than gamma)

What can absorb beta particles?

A sheet of aluminium (around 5mm)

What happens to the nucleus when a beta particle is emitted?

A neutron turns into a proton as the negative charge has left it

What are gamma rays?

Waves of electromagnetic radiation released by the nucleus

What can absorb gamma rays?

Thick sheets of lead or meters of concrete

Why are gamma rays weakly ionising?

Tend to pass through each other rather than collide with atoms

How penetrating are gamma rays?

They penetrate far into materials without being stopped and will travel a long distance through air.

When an unstable nucleus emits an alpha particle what happens?

lose 2 protons 2 neutrons (subtract 4 from mass and 2 from atomic number)

When an unstable nucleus emits a beta particle what happens?

gains a proton (add one to the atomic number)

Equation for neutron emission?

subtract 1 from mass

What do we measure activity in?

Becquerels (Bq), 1 Bq = 1 decay per second

Half life

Time taken for the no. of radioactive nuclei to half in a sample

Where does background radiation come from?

Natural sources such as rocks and cosmic rays from space.

Man-made sources such as the fallout from nuclear weapons testing and nuclear accidents.

What are radiation doses measured in?

Sieverts (Sv) or millisieverts (mSv)

How are nuclear radiation used in medicine?

Exploration of internal organs

control or destruction of unwanted tissue.

Why do we use gamma radiation for medical tracers?

They are less harmful than alpha or beta radiation - want to use isotopes with the shortest half life as possible, emit radiation for a short period of time

How does ionising radiation (beta particles) help in medicines?

Radiotherapy

What does radiation sickness cause?

Vomiting, tiredness, hairloss

Irradiation

The process by which objects are exposed to radiation

What determines how harmful radiation is?

1. type of radiation

2. where your'e exposed to it

3. the amount

What types of radiation are ionising?

alpha, beta, gamma, and X-ray

Why is ionising radiation so dangerous?

They enter living cells and interact with the molecules (ionising DNA - causes mutations = cancer)

What are some non ionising radiation?

UV rays, visible light, infra-red, microwave, and radiowave

which non ionising radiation is still dangerous?

UV rays - cause skin cancer

What precautions can we take when handling radiation?

wearing gloves, overalls, using tongs, keeping item in a lead lined box