# What are the oxidation numbers for ClO-?

Jan 20, 2016

Here's what I got.

#### Explanation:

You're dealing with the hypochlorite anion, ${\text{ClO}}^{-}$, so right from the start you know that the oxidation numbers of the atoms that make up the anion must be equal to $- 1$, the overall charge of the ion.

This means that you can write

$O {N}_{\text{chlorine" + ON_"oxygen}} = - 1$

Now, oxidation numbers are all about electronegativity. As you know, oxidation numbers are assigned with one concept in mind - that more electronegative atoms will take the bonding electrons from the bond it has with a less electronegative atom.

When oxygen is pairred with a less electronegative atom, its oxidation state is always equal to $\textcolor{b l u e}{- 2}$.

In this case, oxygen is indeed more electronegative than chlorine, so you can say that

$O {N}_{\text{chlorine}} + \left(\textcolor{b l u e}{- 2}\right) = - 1$

This means that you have

$O {N}_{\text{chlorine}} = - 1 + 2 = \textcolor{b l u e}{+ 1}$

The oxidation numbers for the atoms that make up the ion are

$\stackrel{\textcolor{b l u e}{+ 1}}{{\text{Cl") stackrel(color(blue)(-2))("O}}^{-}}$