Question

Comment on electronegativity of p in pf3 and pf5

Answer 1

In the Mulliken definition, electronegativity is proportional to the average of the ionization energy and the electron affinity. The reason can be traced to the repulsion between the phosphorus lone pair and the fluoride ion charge in PF4 &. Also realize that the oxidation state of P is +3 in PF3 and +5 in PF5.

Answer 2

The electronegativity of P in $PF_3$ > ectronegativity of P in $PF_5$

Explanation:

The electronegativity of P in $PF_3$ is high than its electronegativity in $PF_5$ .

Electronegativity ∝ Average Ionization Energy

Electronegativity ∝ Electron Affinity

∴ Electronegativity is decided by the repulsion between the phosphorus lone pair and the fluoride ion charge in $PF_3$ and $PF_5.$

Another reason for high electronegativity of P in $PF_3$ is that the oxidation state of P is +3 in $PF_3$ and +5 in $PF_5$.