# What the oxidation states of "ferric ion" or "ferrous ion"?

Jul 8, 2017

When the oxidation state of the metal is $+ I I$ or $+ I I I$......

#### Explanation:

$\text{Ferric}$, $F {e}^{3 +}$, and $\text{ferrous}$, $F {e}^{2 +}$ species are common........For any formula, it useful to be able to quickly assign the oxidation state........

$1.$ $\text{The oxidation number of a free element is always 0.}$

$2.$ $\text{The oxidation number of a mono-atomic ion is equal}$ $\text{to the charge of the ion.}$

$3.$ $\text{For a given bond, X-Y, the bond is split to give } {X}^{+}$ $\text{and}$ ${Y}^{-}$, $\text{where Y is more electronegative than X.}$

$4.$ $\text{The oxidation number of H is +1, but it is -1 in when}$ $\text{combined with less electronegative elements.}$

$5.$ $\text{The oxidation number of O in its}$ compounds $\text{is usually -2, but it is -1 in peroxides.}$

$6.$ $\text{The oxidation number of a Group 1 element}$ $\text{in a compound is +1.}$

$7.$ $\text{The oxidation number of a Group 2 element in}$ $\text{a compound is +2.}$

$8.$ $\text{The oxidation number of a Group 17 element in a binary compound is -1.}$

$9.$ $\text{The sum of the oxidation numbers of all of the atoms}$ $\text{in a neutral compound is 0.}$

$10.$ $\text{The sum of the oxidation numbers in a polyatomic ion}$ $\text{is equal to the charge of the ion.}$

And so for iron complexes and salts such as $F {e}_{2} {\left(C O\right)}_{9}$, $F e C {l}_{3}$, $F e {\left(N {O}_{3}\right)}_{2}$, can you suggest an oxidation state?