Question

During the conversion of ${\mathrm{O}}_2$ to to ${\mathrm{O}}_2^{-}$, the incoming electron goes to the orbital?

Answer 1

Molecular orbital diagram of ${\mathrm{O}}_2$:

• The configuration of ${\mathrm{O}}_2$ : ${\left(\mathrm{\sigma }1\mathrm{s}\right)}^2{\left({\mathrm{\sigma }}^{\ast }1\mathrm{s}\right)}^2{\left(\mathrm{\sigma }2\mathrm{s}\right)}^2{\left({\mathrm{\sigma }}^{\ast }2\mathrm{s}\right)}^2{\left(\mathrm{\sigma }2\mathrm{p}\right)}^2{\left(\mathrm{\pi }2{\mathrm{p}}_{\mathrm{x}}^{}\right)}^2{\left(\mathrm{\pi }2{\mathrm{p}}_{\mathrm{y}}^{}\right)}^2{\left({\mathrm{\pi }}^{\ast }2{\mathrm{p}}_{\mathrm{x}}^{}\right)}^1{({\mathrm{\pi }}^{\ast }2{\mathrm{p}}_{\mathrm{y}}^{})}^1$
• To convert ${\mathrm{O}}_2$ to ${\mathrm{O}}_2^{-}$ one electron needs to be added in the orbital configuration of ${\mathrm{O}}_2$.
• As per Aufbau's principle the electrons enters in lower energy orbital first.
• So from the orbital diagram we can see that electron will enter in ${\mathrm{\pi }}^{*}2{\mathrm{p}}_{\mathrm{x}}$ orbital.

Hence, During the conversion of ${\mathrm{O}}_2$ to to ${\mathrm{O}}_2^{-}$, the incoming electron goes to ${\mathrm{\pi }}^{*}2{\mathrm{p}}_{\mathrm{x}}$ orbital.