Chapter 21, Problem 21.4A

Interpretation Introduction

Interpretation:

In the compound ${[\text{Cr}{({\text{NH}}_3)}_2{\left(\text{SCN}\right)}_4]}^{-}$, the oxidation state of $\text{Cr}$ is to be determined.

Concept introduction:

In the polyatomic ion, the number of oxidation numbers is equal to the charge of the ion. The sum of the oxidation number of all the atoms that are present in the neutral compound is equal to zero

(a). The oxidation number will be zero for the free elements.

(b). For the first group element, the oxidation number will be $+1$.

(c). For the second group element, the oxidation number will be $+2$.

(c). For the seventeen-group element, the oxidation number will be $-1$.