# Can Someone help me please? Thanks!

Aug 22, 2017

We gots $\stackrel{+ V I I}{\text{Cl}}$ in $\text{perchlorate.........}$

#### Explanation:

The sum of the oxidation numbers is equal to the charge on the ion; here we gots $C l {O}_{4}^{-}$. The oxidation state of oxygen is usually $- I I$ and it is here.....

And thus $C {l}_{\text{oxidation number}} + 4 \times \left(- 2\right) = - 1$

It does not take too much arithmetic to see that $C l$ has an oxidation number of $+ V I I$.

What about for $B r {O}_{4}^{-}$, $C l {O}_{3}^{-}$ ion, and $C l {O}^{-}$? Please put the answer in the comments.

And what is the oxidation number of aluminum?