radioactivity

• Beta decay is a type of radioactive decay in which a beta particle, either an electron or a positron, is emitted from an atomic nucleus.
• alpha decay is made up of 2 protons plus 2 neutrons
• gamma radiation is an electromagnetic radiation from the nucleus of an atom
• The charge of alpha radiation is 2 plus
• the charge of beta radiation is -1
• the charge of gamma radiation is nothing
• alpha radiation will absorb a thin sheet of paper
• beta radiation will absorb an aluminium sheet or lead sheet
• gamma radiation will absorb a thick lead sheet or concrete
• alpha radiations range in air is 5cm
• beta radiations range in air is 1m
• gamma radiations range in air is unlimited
• alpha radiation is strongly ionising
• beta radiation is moderately ionising
• gamma radiation is weakly ionising
• alpha particles are deflected in the opposite direction of beta particles
• alpha particles are deflected by electric and magnetic fields
• beta particles are deflected from electric and magnetic fields but in the opposite direction of alpha particles
• gamma particles are not deflected by electric and magnetic fields
• an isotope is an atom of the same element that has a different number of neutrons relative to carbon dioxide but has the same number of protons and electrons
• ions are atoms which have gained or lost electrons
• The bigger the dose of radioactivity the more likely someone is to develop cancers. Smaller doses pose less risk but the risk is never zero
• alpha radiation is the most dangerous because the radiation affects all the surrounding tissue and outside the body it is absorbed by the skin so affects skin and retinal cells
• contamination is the unwanted presence of radioactive atoms
• irradiation is when a person or object is exposed to a radioactive source
• some nuclei are unstable and become more stable by decaying and emitting radiation which is a random process. We cannot predict when any nucleus will decay.
• we measure radiation using a geiger muller tube
• half life is the time taken for the activity to fall to half of its initial value
• nuclear fission is the splitting of one large nucleus into smaller nuclei, and energy in the form of heat
• nuclear fusion is the joining of two atomic nuclei to form one larger nucleus
• in order for nuclear fusion to occur plasma must be contained with a very strong magnetic field
• nuclear fissions generate radioactive waste and their is a high risk of disaster (nuclear meltdown)
• nuclear fusion has no radioactive waste, no greenhouse gases and is readily available as heavy hydrogen occurs in the sea
• nuclear fusion needs very high temperatures and pressures in order to take place and to overcome the electrostatic force of repulsion between nuclei
• nuclear fission power stations work in the same way as a fossil fuel except we have a nuclear reactor instead of a boiler
• radiation can penetrate substances and knock electrons out of atoms. This is why they are ionising
• unstable atoms can become stable by emitting radiation
• Control Rods: Rods found in nuclear reactors to absorb neutrons and control the rate of reaction.
• gamma radiation is used to kill cancer cells because it has a longer half life.
• radiation beams aim at the tumour from different directions as the radiation will kill all the cells so the tumour will receive a high dose whereas the surrounding tissue will receive a smaller dose.