the oxidation states of the elements Fe and Br needs to be determined.
Fe is a transition element therefore is capable of multiple oxidation states.
an ionic compound is made with Fe as the cation and halide ion as anion
Br⁻ which is a halogen has a charge of -1.
In ions the charge of the ion is equal to the oxidation state of the ion. Br⁻ has oxidation state of -1.
FeBr₂ is a compound therefore net charge is 0.
the sum of the products of the oxidation states of the individual elements by the number of atoms should add upto the net charge
oxidation number of Fe cation + (oxidation number of Br⁻ x 2) = 0
say the oxidation state of Fe is X and oxidation number of Br⁻ is -1
X + (2 x -1)= 0
X - 2 = 0
X = 2
this means that oxidation number of Fe is +2
and oxidation number of Br is -1
