1. ## oxidation

Determine the oxidation number of the specified element.
Cr in CrO4$\displaystyle ^2-$

2. Originally Posted by johett
Determine the oxidation number of the specified element.
Cr in CrO4$\displaystyle ^2-$
well this is not math xD

but I know the answer, I think that you mean:

$\displaystyle CrO_4^{ - 2}$

to answer this problem you must know that, the oxidation number of oxigen y -2, then we have this equation:

$\displaystyle Cr + 4 \cdot - 2 = - 2 \Leftrightarrow \boxed{Cr = 6}$