These are different chemical compounds that contain iron (Fe) in various oxidation states and in combination with different elements:
Fe: Iron in its elemental formFeO: Iron oxide, with iron in the +2 oxidation stateFeCl2: Iron chloride, with iron in the +2 oxidation stateFe(OH)2: Iron hydroxide, with iron in the +2 oxidation stateFeSO4: Iron sulfate, with iron in the +2 oxidation stateFe(NO3)2: Iron nitrate, with iron in the +2 oxidation state
These are different chemical compounds that contain iron (Fe) in various oxidation states and in combination with different elements:
Fe: Iron in its elemental formFeO: Iron oxide, with iron in the +2 oxidation stateFeCl2: Iron chloride, with iron in the +2 oxidation stateFe(OH)2: Iron hydroxide, with iron in the +2 oxidation stateFeSO4: Iron sulfate, with iron in the +2 oxidation stateFe(NO3)2: Iron nitrate, with iron in the +2 oxidation state