The table below shows the main oxidation states of the Group elements. The major features of the redox chemistry of elements in this group are:
 

• Like oxygen, fluorine only has negative oxidation states.
• The most stable state for all elements is -1.
• All of the elements and the compounds containing halogen in positive oxidation states are oxidants.
• Despite being the most stable state for iodine, I^– is a reasonable reductant in aqueous solution.
   

  F		Cl		Br		I
  		+7 (ClO4–)		+7		+7
  		+5 (ClO3–)		+5		+5
  		+3 (ClO2–)
  		+1 (ClO–)		+1		+1
  0 (F2)		0 (Cl2)		0 (Br2)		0 (I2)
  –1* (F–)		–1* (Cl–)		–1* (Br–)		–1* (I–)

  
   
• With the exception of fluorine, halogens and their oxoanions are susceptible to autooxidation-reduction (disproportionation).
  
  Autooxidation-reduction (disproportionation) is a reaction in which atoms of the same element act as both the oxidant and the reductant. Therefore in order to undergo auto-oxidation-reduction reaction, an atom of an element must be in an intermediate oxidation state.
  
  For example Cl₂ (oxidation state 0) reacts with water to to form HOCl (Cl oxidation state +1) and HCl (Cl oxidation state -1).