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P3 Topic 3: Production, uses and risks of ionising radiation from radioactive sources
In an atom, as said before, the number of protons and electrons are the same. Atoms with different numbers
of neutrons but are the same element are called isotopes.
An atom is electrically neutral as equal number…

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- decay increases the atomic number by one but leaves the mass number unaffected.

Beta plus (+) decay

In + decay a proton becomes a neutron plus a positron. Positron decay decreases the atomic number by one
but leaves the mass number unaffected.

Alpha radiation

Each alpha particle is made…

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An isotope which lies above the curve has too many neutrons to be stable. An isotope which lies under the
curve has too little neutrons to be stable.
The N=Z curve stops when the proton number goes about 82 as all isotopes are unstable above this number.

When there are:…

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Tracers in Medicine

The radioactive isotopes used in tracers always have short half lives.
The tracer is injected into the patient or swallowed. An external detector follows its progress as it moves
around the body. The radiation emitted can be used by a computer to create an image to show…

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Internal and external radiation

Tumours can be treated with internal radiation or external radiation. External radiation uses high-energy
X-rays or gamma rays to destroy the cancer cells. The radiation is closely focused on the tumour but it is
inevitable that some healthy cells may be damaged.
Internal radiation uses an…


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