topic 7 radioactivity and particles

• irrigation is the process of being exposed radiation. irradiation material does not make that material radioactive but it can kill living cells
• contamination is the unwanted presence of radioactive atom found on an area, this makes the areas radioactive
• nuclear radiation is ionising radiation emitted from unstable nuclei in a random process
• geiger muller counter can detect ionising radiations, detects the number of atoms going through radioactive decay
• dangers of ionising radiation include, damage of DNA which can cause caner, mutations, damage to cells and tissues
• background radiation is radiation that exists around us all the time, natural sources include food and drink. artificial sources include nuclear waste
• alpha is 4,2, few centimetres, can be blocked by paper, least penetrating
• structure of an atom, nucleus has protons and neutrons, electron shell has the electrons
• experiment, alpha is blocked by paper, beta is blocked by a thin sheet of metal such as aluminium, gamma is blocked by a sheet of thick lead
• isotopes are atoms with the same number of protons but different number of neutrons
• beta is 0,-1, can travel a few metres, blocked by a sheet of aluminium, middle penetrating
• neutron radiation 1,0
• mass number top is proton and neutron, atomic number bottom number of protons
• gamma is 0,0, can travel very long distances, can be blocked by thick lead plates, most penetrating
• the half life of an isotope is the time taken for Half the nuclei to decay or the time taken for the activity to halve
• nuclear reactor, uses nuclear fission to generate electricity, heat generated from fission turns water into steam. the steam turns a turbine to generate electricity for the national grid
• the control rods, made of materials that absorb neutrons and are used to control chain reactions, e.g boron
• the moderator, fuel rods are encased in the moderator (graphite) and help the fission reaction to proceed efficiently
• energy source for stars is nuclear fusion
• role of shielding is the reactors waste is radioactive, radiation can cause cancer
• chain reaction is a self sustaining series of reactions in which the neutrons produced in one fission reaction cause more fission reactions to occur.
• nuclear fusion is the joining of two small light nuclei to from a larger heavier one and release energy, it has to happen at high pressure and temperature, electrostatic repulsion of protons can happen
• nuclear fission is when a large nucleus absorbs a neutron and splits into two smaller nuclei, daughter nuclei, releasing large amounts of heat energy and two, three new neutrons
• nuclear reactions are, fission, fusion and radioactive decay and can be used as a source of energy
• nuclear equations https://www.tutormyself.com/7-08-understand-how-to-balance-nuclear-equations-in-terms-of-mass-and-charge/