The correct increasing order of bond length among the following is
To determine the correct increasing order of bond length among the given species (, , , and ), we can use Molecular Orbital (MO) theory to calculate the bond order for each species.
The relationship between bond order and bond length is inversely proportional:
This means that a higher bond order corresponds to a shorter bond length, and a lower bond order corresponds to a longer bond length.
Let us first write down the molecular orbital configuration for the oxygen molecule (), which has 16 electrons:
The formula for calculating Bond Order (BO) is:
where is the number of bonding electrons and is the number of antibonding electrons.
Now, we calculate the bond order for each given species:
1. For (15 electrons):
One electron is removed from the antibonding molecular orbital ( or ).
Number of bonding electrons,
Number of antibonding electrons,
2. For (16 electrons):
Number of bonding electrons,
Number of antibonding electrons,
3. For (17 electrons):
One electron is added to the antibonding molecular orbital.
Number of bonding electrons,
Number of antibonding electrons,
4. For (18 electrons):
Two electrons are added to the antibonding molecular orbitals.
Number of bonding electrons,
Number of antibonding electrons,
Comparing the calculated bond orders:
Since bond length is inversely proportional to bond order, the increasing order of bond length is the reverse of the bond order sequence:
Therefore, the correct increasing order of bond length is: