This Study Mind Tutorial covers the following specification points:

Edexcel: 6.15(i,ii), 6.23, 6.5

6.15. know that a radical:

(i) is a species with an unpaired electron and is represented in mechanisms by a single dot

(ii) is formed by homolytic fission of a covalent bond and results in the formation of radicals

6.23. understand that heterolytic bond fission of a covalent bond results in the formation of ions

6.5. be able to classify reactions as addition, elimination, substitution, oxidation, reduction, hydrolysis or polymerisation