rules for assigning oxidation states

the oxidation state of an atom in a free element (Fe, H, Cl) or in the molecular form of an element (Cl2, S8) is zero

;)

the sum of oxidation states for all atoms in a compound equals the charge of the compound

-neutral molecules/formula units: oxidation states must sum to 0

—in H2O all oxidation states sym to zero

-ions: oxidation states must sum to the total charge of the ion

—for Fe3+ the oxidation state of iron is +3

—in NO3+, the oxidation states sum to +1

Fluorine, group 1, and group two always have the same oxidation state

-group one +1

-F -1

-group two +2

if hydrogen is NOT bonded to a metal its oxidation state is +1

;)

if oxygen is not bonded to itself (O2) or Fluorine, its oxidation state is -2

;)