Question
Chemistry Question on Chemical bonding and molecular structure
Which of the following represents the arrangement in increasing order of bond order and bond dissociation energy?
A
O2+<O22−<O2−<O2
B
O22−<O2−<O2<O2+
C
O2<O2+<O22−<O2−
D
O22−<O2−<O2+<O2
Answer
O22−<O2−<O2<O2+
Explanation
Solution
The MO configuration of O2 can be written as
O2(8+8=16)=σ1s2,σ∗1s2,σ2s2,σ∗2s2,σ2pz2,π2px2≈π∗2py2,π∗2px1≈π2py1
∴ Bond order
=2Nb−Na=210−6=2
Similarly,
O2+(8+8−1=15),
BO=210−5=2.5
O2−(8+8+1=17),
BO=210−7=1.5
O22−(8+8+2=18)
BO=210−8=1
Thus, the order of bond order (BO) and bond dissociation energy is
O22−<O2−<O2<O2+