# What is the oxidation number of the Ni atom in Ni_3(PO_4)_2?

May 23, 2016

We first work out the charge of the $P {O}_{4}$-group.

#### Explanation:

$P$ can be either $+ 3 \mathmr{and} + 5$
In this case it must be $+ 5$ or it wouldn't work out with the rest.

So $P {O}_{4} = + 5 + 4 \cdot \left(- 2\right) = - 3$, so it's $P {O}_{4}^{3 -}$

There are 2 $P {O}_{4}^{3 -}$'s for a total charge of $- 6$

To balance that, the three $N i$'s must have a charge of $+ 2$ each.

So the oxidation number is $N {i}^{2 +}$