The first part of this module is designed to acquaint you

• with the oxidation states of titanium, vanadium and chromium and
  
   
• with reagents that are
  
  
  • reductants donate electrons to the metal and make its oxidation state more negative).
    Examples are Sn²⁺, HSO₃^–, I^–- and metals.
    
     
  • oxidants (accept electrons from the metal and make its oxidation state more positive).
    Examples are O₂ and the halogens (Cl₂, Br₂ and I₂)
    
     
  • do not change the oxidation state of the metal, but change the species in which it occurs.
    H₂O, H⁺(aq) and OH^–(aq) are reagents which USUALLY react this way.