Given the reaction below, which is the reduced substance?
#Mg + Cl_2 -> Mg^(2+) + 2Cl^-#
The chlorine molecule is REDUCED........
And we may represent this by the reduction reaction in which electrons appear as stoichiometric reagents........
Zerovalent chlorine gas,
And of course, for every reduction, for every electron GAIN, there must be a corresponding oxidation, an electron loss. And metals, especially alkali and alkaline earth metals, are typically oxidized............
And for the final reaction we SUM the individual oxidation and reduction reactions in such a way that electrons DO NOT appear in the final reaction. Here it is simply