Question

The bond length of N2 increases upon removing an electron while that of O2 decreases upon removing an electron. The experimental values of bond lengths of N2 and N2 + are 1.094 Å and 1.116 Å, respectively. The experimental values of bond lengths of O2 and O2 + are 1.207 Å and 1.123 Å, respectively. Account for this trend using MO theory and bond order.

Answer 1

for N2 and N2+, N2 has a bond order of 3 as it has 6 electrons in highest bonding orbital and no electron in the corresponding antibonding orbital, so bond is 6-0/2 = 3. now when one electron is removed to make N2+ the electrons in bonding orbital is 5 and Bond order is 5-0/2= 2.5 . also we know that when bond order decreases, strength decreases and bond length increases. So the data observed is correct.

for O2 and O2+, O2 has bonding molecular electron as 6 and antibonding electrons are 2 = so B.O = 6-2/2= 2 . and when an electron is removed from O2 the electron from antibonding orbital i.e 1 electron from the 2 will go out then the bond order will be 6-1/2=2.5. so the bond order will increase. hence the bond length will decrease.