Radioactivity

Radioactivity

1. Proton

   • Relative charge = +1
     • Relative mass = 1.0
   • Makes nucleus

2. Atomic number = protons (bottom)

   • Mass number = protons and neutrons (top)

3. Neutron

   • Relative mass = 1.001
     • Relative charge = 0

4. Electron

   • Relative mass = 1/1838
     • Relative charge = -1
   • Form a loose cloud on the outside of an atom

5. Radioactive Decay

   • When unstable nuclei 'decay' and break apart into more stable nuclei.
   • Radioactive atoms
     • Emit either alpha, beta or gamma
       • Ionising radiation (nuclear radiation)
       • alpha
         • + charge
         • 2 protons, 2 neutrons
         • Penetrates 4-10cm of air
           • Stopped by a sheet of paper
       • beta
         • - charged
         • Identical to electron
         • Pentrates about 1m of air
           • Stopped by a few mm of aluminium
       • gamma
         • uncharged
         • Penetrates almost no limit in air
           • Intensity reduced by several cm of lead or serveral metres of concrete