Nuclear Physics

Nuclear Physics

1. The atom

   • The atoms of an element contain equal numbers of protons and electrons and so have no overall charge
   • Proton: Mass=1 Charge=+1 Location= Nucleus
     • Neutron: Mass=1 Charge=0 Location=Nucleus
       • Electron: Mass= 1/1836 Charge= -1 Location= Orbiting nucleus in shells
   • Isotopes are different forms of the same element, same number of protons but different numbers of neutrons, most elements have different isotopes but there's normally only one or two stable ones, the others ones tend to be radioactive meaning the decay into other elements giving out radiation,

2. Radioactivity

   • In a radioactive isotope, the nuclei are unstable and so they emit radiation in the form of particles or waves to form a more stable atom
   • A natural phenomena- the individual nuclei decay in a spontaneous and random manner
     • Spontaneous- We cannot control the decay of the radioactive nuclei we cannot make it happen or stop it from happening
     • Random- We cannot predict which nucleus will decay next or when it will decay
   • Radioactive substances give out radiation all the time and their behaviour cannot be changed by chemical or physical processes.
   • A substance is radioactive if tis nuclei are unstable and decay randomly and spontaneously, emmitting radiation, to become more stable
     • Ionising radiation damages the DNA of cells and can lead to tumors
   • Measured with a Geiger counter in Becqurel (Bq) or counts per minute (cpm)
   • Ionisation- The loss/gain of electrons from atoms forming ions

3. Types of radiation

   • Alpha particles- 2 neutrons, 2 protons (same as He nucleus), +2 charge, RAM=4, stopped by paper or a few centimetres of air, strongly ionising
   • Beta particles- high energy electron,-1 charge, RAM=0, stopped by a few mm of aluminium, weakly ionising
   • Gamma Radiation- high energy electromagnetic radiation, 0 charge RAM=0, stopped by thick lead or concrete, very weakly ionising
   • REMEMBER TO LOOK AT EQUATIONS

4. Background Radiation

   • The radiation that is present when all other sources have been removed.
   • Occurs naturally, always there, comes from natural sources like; cosmic rays, rocks, radon gas, medical treatments