Radiation

• How do we measure the number of undecayed nuclei?

  in becquerels
• what measures radiation?

  Geiger counter
• What is an isotope?

  an element that has the same number of protons but a different number of neutrons
• How are alpha particles created?

  4 particles are spat out of the overcrowded nucleus (2 protons & 2 neutron)
• How is a beta particle created?

  a Neutron splits into a proton and an electron, the electron is the beta particle
• What is gamma radiation?

  a wave
• What charge does alpha have?

  2+
• What charge does beta have?

  -ve
• True or false gamma has no charge. True
• What is alpha radiation stopped by?

  Paper
• What is beta stopped by?

  thin aluminium
• What is gamma stopped by?

  thick lead
• The half-life of a radioactive substance is the time taken for half of the unstable radioactive nuclei to decay
• what type of ionisation does alpha have?

  intense ionisation
• What type of ionisation does beta have?

  mild ionisation
• What type of ionisation does gamma have?

  weak ionisation
• Radioactive decay is spontaneous, you can not cause or influence the decay
• Radioactivity is random meaning it is impossible to tell when a particular radioactive nucleus will decay
• Ionisation is generally not dangerous however if it occurs in the nucleus of a cell it can disrupt the DNA causing them to mutate, causing cancer
• What is the definition of contamination?

  when nuclear material gets onto a person
• What is the definition of irradiation?

  Exposure to radiation.
• What is a safety precaution for contamination?

  wash after exposure, wear a Hazmat suit
• Safety precautions for irradiation are to put lead screening up or to walk away from it so you are only exposed for a short amount of time
• true or false: when irradiated an object will become radioactive. False
• Fusion involves the small nuclei joining together to form larger ones
• Temperatures of millions of degrees are needed to start the reaction of nuclear fusion
• The products of fusion have slightly less mass than the reactants with the missing mass being converted to energy
• Nuclear fussion release more energy than fission
• Fusion make less radioactive products as many of the products are stable compared to fission
• Fusion can not have a chain reaction
• Nuclear fission is when a nuclei of uranium 235 gains a neutron causing it to split into two radioactive daughter nuclei
• The small mass lost in a fission reaction is converted to lots of energy
• the products of nuclear fission are: two daughter nucleI, 3 neutrons, lots of energy
• The neutrons left over from one fission can go on to create other fissions, causing a chain reaction
• The energy from nuclear fission is in the form of the kinetic energy of the particles
• In a nuclear reactor the fuel rods are where the uranium is put
• A control rod absorbs some of the neutrons so that they don't cause too many fissions at once
• A control rod is made of boron
• Neutrons with kinetic energy are very quick so need to be slowed down by the moderator
• The moderator is made of carbon in the form of graphite