Use molecular orbital theory to predict whether the bond order in the superoxide ion, O2-, should be higher or lower than the bond order in neutral O2 molecule.

Is the bond order of O2- higer or lower than that of O2?

it is lower

O2 BO=2

O2- BO=1.5

To determine whether the bond order of the superoxide ion (O2-) is higher or lower than that of the neutral O2 molecule, we need to apply molecular orbital theory.

Molecular orbital theory describes the formation of molecular orbitals by the combination of atomic orbitals from the participating atoms. In this case, we will consider the molecular orbitals of oxygen.

In the O2 molecule, there are a total of 16 valence electrons (8 from each oxygen atom). According to molecular orbital theory, these electrons fill molecular orbitals starting with the lowest energy orbitals. The molecular orbital diagram for O2 is as follows:

σ(1s) (bonding)
σ*(1s) (anti-bonding)
σ(2s) (bonding)
σ*(2s) (anti-bonding)
π(2px) (bonding)
π*(2px) (anti-bonding)
π(2py) (bonding)
π*(2py) (anti-bonding)
σ(2pz) (bonding)
σ*(2pz) (anti-bonding)

Based on the filling of these molecular orbitals, we can calculate the bond order using the formula:

Bond Order = (Number of bonding electrons - Number of anti-bonding electrons) / 2

For O2, there are 10 bonding electrons (σ(1s), σ(2s), π(2px), π(2py), and σ(2pz)) and 6 anti-bonding electrons (σ*(1s), σ*(2s), π*(2px), π*(2py), σ*(2pz)). Thus, the bond order of O2 is (10 - 6) / 2 = 2.

Now let's consider the superoxide ion (O2-). In this case, we need to add one additional electron to the O2 molecular orbital diagram. This extra electron occupies the σ*(2px) anti-bonding orbital, resulting in the following electron configuration:

σ(1s) (bonding)
σ*(1s) (anti-bonding)
σ(2s) (bonding)
σ*(2s) (anti-bonding)
π(2px) (bonding)
π*(2px) (anti-bonding, occupied by extra electron)
π(2py) (bonding)
π*(2py) (anti-bonding)
σ(2pz) (bonding)
σ*(2pz) (anti-bonding)

Now, calculating the bond order for the superoxide ion, O2-, we find that there are 10 bonding electrons and 7 anti-bonding electrons. Therefore, the bond order of O2- is (10 - 7) / 2 = 1.5.

In conclusion, the bond order of the superoxide ion (O2-) is lower than that of the neutral O2 molecule.