Question

Calculate the bond order of ${\mathrm{O}}_2$.

Answer 1

Calculation of bond order of ${\mathrm{O}}_2$

Step 1: Calculating the total number of electrons in ${\mathrm{O}}_2$
Number of electrons in Oxygen(8) = 8
Number of electrons in ${\mathrm{O}}_2$ = $2\times 8$
Number of electrons in ${\mathrm{O}}_2$ = 16

Step 2: Determining the electronic configuration of ${\mathrm{O}}_2$
${\left[\mathrm{\sigma }\right(1\mathrm{s}\left)\right]}^2{\left[{\mathrm{\sigma }}^{\ast }\right(1\mathrm{s}\left)\right]}^2{\left[\mathrm{\sigma }\right(2\mathrm{s}\left)\right]}^2{\left[{\mathrm{\sigma }}^{\ast }\right(2\mathrm{s}\left)\right]}^2{\left[\mathrm{\sigma }\right(1\mathrm{pz}\left)\right]}^2{\left[\mathrm{\pi }\right(2\mathrm{px}\left)\right]}^2{\left[\mathrm{\pi }\right(2\mathrm{py}\left)\right]}^2{\left[{\mathrm{\pi }}^{\ast }\right(2\mathrm{px}\left)\right]}^1{\left[{\mathrm{\pi }}^{\ast }\right(2\mathrm{py}\left)\right]}^1$

The number of bonding electrons = 10

The number of anti-bonding electrons = 6

Step 3: Calculating the bond order of ${\mathrm{O}}_2$
Bond order = $\frac{\mathrm{Number}\mathrm{of}\mathrm{electrons}\mathrm{in}\mathrm{bonding}-\mathrm{Number}\mathrm{of}\mathrm{electrons}\mathrm{in}\mathrm{antibonding}}{2}$
Bond order = $\frac{10-6}{2}$

Bond order = $\frac{4}{2}$

Bond order = 2

Hence, the bond order for ${\mathrm{O}}_2$ is 2.