Question

What is the oxidation number of the phosphorus in ${\mathrm{PF}}_3$?

Answer 1

Oxidation number: Oxidation number denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron pair in a covalent bond belongs entirely to a more electronegative element.

Calculating the oxidation number of Phosphorous(P) in ${\mathrm{PF}}_3$:

The oxidation state of Fluorine(F) = +1

Consider the oxidation state of Phosphrous(P) = x

Now,

$$\begin{gathered} x+\left(-1\times 3\right)=0 \\ x=+3 \end{gathered}$$

Hence, the oxidation number of phosphorus in ${\mathrm{PF}}_3$ is $+3$.