Chapter 9, Problem 9.9P

Interpretation Introduction

Interpretation:

The ground state configuration, bond order and the magnetic nature of the species has to be given.

Concept Introduction:

Bond order of a molecule or ion is calculated by the following formula,

Bond order $\text{=}\frac{\left({\text{N}}_{\text{b}}\right)\text{-}\left({\text{N}}_{\text{a}}\right)}{\text{2}}$

Where, ${\text{N}}_{\text{b}}$ is number of electrons in bonding orbital.

${\text{N}}_{\text{a}}$ is number of electrons in antibonding orbital.

Paramagnetic and diamagnetic compounds:

Paramagnetic compounds have unpaired electrons and are attracted to magnetic field whereas diamagnetic compounds have paired spins and are repelled by the magnetic field.

Explanation of Solution

The ground state electronic configuration is the arrangement of electrons around the nucleus of an atom with lower energy levels.

Ground state electronic configurations of three species are as follows,

  $\text{NF}\text{=}{\left(\text{σ1s}\right)}^{\text{2}}{\left({\text{σ}}^{\text{*}}\text{1s}\right)}^{\text{2}}{\left(\text{σ2s}\right)}^{\text{2}}{\left({\text{σ}}^{\text{*}}\text{2s}\right)}^{\text{2}}{\left({\text{σ2p}}_{\text{z}}\right)}^{\text{2}}{\left({\text{π2p}}_{\text{x}}\right)}^{\text{2}}{\left({\text{π2p}}_{\text{y}}\right)}^{\text{2}}{\left({\text{π}}^{\text{*}}{\text{2p}}_{\text{x}}\right)}^{\text{1}}{\left({\text{π}}^{\text{*}}{\text{2p}}_{\text{y}}\right)}^{\text{1}}$

  $\text{NF}{}^{\text{+}}\text{=}{\left(\text{σ1s}\right)}^{\text{2}}{\left({\text{σ}}^{\text{*}}\text{1s}\right)}^{\text{2}}{\left(\text{σ2s}\right)}^{\text{2}}{\left({\text{σ}}^{\text{*}}\text{2s}\right)}^{\text{2}}{\left({\text{σ2p}}_{\text{z}}\right)}^{\text{2}}{\left({\text{π2p}}_{\text{x}}\right)}^{\text{2}}{\left({\text{π2p}}_{\text{y}}\right)}^{\text{2}}{\left({\text{π}}^{\text{*}}{\text{2p}}_{\text{x}}\right)}^{\text{1}}$

  $\text{NF}{}^{\text{-}}\text{=}{\left(\text{σ1s}\right)}^{\text{2}}{\left({\text{σ}}^{\text{*}}\text{1s}\right)}^{\text{2}}{\left(\text{σ2s}\right)}^{\text{2}}{\left({\text{σ}}^{\text{*}}\text{2s}\right)}^{\text{2}}{\left({\text{σ2p}}_{\text{z}}\right)}^{\text{2}}{\left({\text{π2p}}_{\text{x}}\right)}^{\text{2}}{\left({\text{π2p}}_{\text{y}}\right)}^{\text{2}}{\left({\text{π}}^{\text{*}}{\text{2p}}_{\text{x}}\right)}^{\text{2}}{\left({\text{π}}^{\text{*}}{\text{2p}}_{\text{y}}\right)}^{\text{1}}$

All the three species have lone pair electrons in their antibonding orbitals.  Thus, they get attracted by the magnetic field.  Hence, they are paramagnetic species.

Bond order calculation:

$\text{NF}$ molecule has the same configuration as oxygen molecule thus, the bond order of $\text{NF}$ molecule is two.

Bond order of $\text{NF}$ can be calculated as,

  $\begin{array}{l}\text{Bond order}\text{=}\frac{\left(\text{10}\right)\text{-}\left(\text{6}\right)}{\text{2}}\\ \text{ =}\frac{\text{4}}{\text{2}}\\ \text{=2}\end{array}$

${\text{NF}}^{\text{+}}$ ion is formed when $\text{NF}$ molecule loses one of its electron.

Bond order of ${\text{NF}}^{\text{+}}$ can be calculated as,

  $\begin{array}{l}\text{Bond order}\text{=}\frac{\left(\text{10}\right)\text{-}\left(\text{5}\right)}{\text{2}}\\ \text{ =}\frac{\text{5}}{\text{2}}\\ \text{=2}\text{.5}\end{array}$

The bond order of ${\text{NF}}^{\text{+}}$ is 2.5.

Bond order of ${\text{NF}}^{\text{-}}$ can be calculated as

  $\begin{array}{l}\text{Bond order}\text{=}\frac{\left(\text{10}\right)\text{-}\left(7\right)}{\text{2}}\\ \text{ =}\frac{3}{\text{2}}\\ \text{=1}\text{.5}\end{array}$

The bond order of ${\text{NF}}^{\text{-}}$ is 1.5.