# What are the oxidation states of the metal in FeCl_4^(2-) and Cr_2O_7^(2-)?

May 28, 2017

We has $F e \left(I I +\right)$, and $C r \left(V I +\right) \ldots \ldots \ldots$

#### Explanation:

$\text{Chromate ion}$ $\equiv$ $C r {O}_{4}^{2 -}$.

The typical oxidation state of oxygen is $- I I$, and it is here. And since the sum of the oxidation states equals the charge on the ion, which is $- 2$, $C {r}_{\text{oxidation number}} + 4 \times \left(- 2\right) = - 2$

$C {r}_{\text{oxidation number}} = C r \left(V I +\right)$.

What about $\text{dichromate}$, $C {r}_{2} {O}_{7}^{2 -}$?