radical substitution

• step 1- initiation

  halogen absorbs UV light that is enough energy to break halogen bond

  atoms are identical so split evenly

  each halogen atom takes 1 electron from bond

  radical is formed
• Step 2- propagation 


  radical reacts with a molecule

  new radical is formed and causes a continuous chain reaction

  alkane free radical is very reactive so forms a bond with the halogen
• propagation is when a radical is used up and created in a chain reaction
• stage 3 termination 


  radicals are destroyed in termination reaction this stops a chain reaction

  this is when two radicals react to form a unreactive molecule
• why are chain reactions not useful

  make lots of different halogenalkanes

  mixture of products will then need to be extracted