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Physics (P4-Atomic Structure (RADIATION IN MEDICINE (It can be used as a…
Physics
P4-Atomic Structure
STRUCTURE OF AN ATOM
In the nucleus there are protons and neutrons and around the centre there are electrons in fixed energy levels.
RADIATION
Electromagnetic radiation causes and electron to jump to a higher energy level and when radiation is emitted it moves back to it's original shell
ELEMENTS
All elements have an atomic number that is always the same and an atomic mass that can change. Isotopes are atoms that have extra neutrons.
ALPHA
Alpha radiation is the most ionising, which means that it tries to find protons to neutralise it. This can result in mutated DNA. They consist of two protons and two neutrons. Alpha is the least penetrating so it is only dangerous if ingested. The atomic number is decreased by two and the mass number by 4
RADIOACTIVE DECAY
Nuclei that are unstable decay. This is called radioactive decay. When they decay they give out radiation. This is random. Activity is the rate at which things decay.
BETA
Beta radiation is an electron that has been released from the nucleus because a neutron has split into an electron and is quite ionising. It is stopped by a few mm of aluminium. The mass stays the same but the atomic number increases by 1.
GAMMA
Gamma radiation can travel the furthest, isn't very ionising and is stopped by a few cm of lead. It is electromagnetic radiation. The atomic and mass number stay the same.
HALF LIFE
The time it takes for the number of nuclei to halve. Short half lives give high doses in a short amount of time. Long half lives involve long doses in a long amount of time.
DANGERS
Irradiation is when an object is exposed to radiation. This doesn't mean that the object becomes radioactive. Contamination is where an object is in contact with radiation. This makes the object radioactive.
BACKGROUND RADIATION
This is the constant low level radiation in the environment. This can be caused by rocks, cosmic rays and medicine
RADIATION IN MEDICINE
It can be used as a tracer, the isotope is injected and then accumulates in the affected area. This then releases emissions that can be detected. Cameras scan the area for signs of the isotope. The isotope should have a short half life
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FISSION
Large unstable atoms split and a neutron is fired at one. This then produces neutrons and gamma radiation and two daughter nuclei and energy. This is a chain reaction.
FUSION
This is the joining of two small nuclei to make a large one. This takes place in stars. A lot of energy is produced.