In which of the following pair both species have compairable bond order.
(1)
O2[AsF6], BaO2[O-O bond order]
(2)
C2, CaC2[C-C bond order]
(3)
C2H2, CaC2[C-C bond order]
(4)
CaC2, N2–2[C-C and N-N bond order]
Answers
Answer:
Bond order = 1/2×(N
B
−N
AB
)
Order of filling MO is:
1. N
2
:
valence electrons=5+5=10
(σ2s)
2
(σ∗2s)
2
(σ2p)
2
(π2p)
4
BO=1/2×(6−0)=3;
2. N
2
−
:
valence electrons=5+5+1=11
(σ2s)
2
(σ∗2s)
2
(σ2p)
2
(π2p)
4
(π
∗
2p)
1
BO=1/2×(6−1)=2.5;
3.O
2
:
valence electrons=6+6=12
(σ2s)
2
(σ∗2s)
2
(σ2p)
2
(π2p)
4
(π
∗
2p)
2
BO=1/2×(6−2)=2;
4. O
2
−
:
valence electrons=6+6+1=13
(σ2s)
2
(σ∗2s)
2
(σ2p)
2
(π2p)
4
(π
∗
2p)
3
BO=1/2×(6−3)=1.5;
Bond strength ∝bond order
bond strength/order: N
2
>N
2
−
and O
2
>O
2
−
Therefore, B is correct.
The pair both species have compairable bond order is
The pair both species have compairable bond order is (3) C2H2, CaC2[C-C bond order]
- Bond order is defined as the half the difference between the number of bonding and antibonding electrons.
- Bond order is the index of bond strength means more the bond order, more is the bond strength. Stable bonds have positive bond order.
- So, in the C2H2 and CaC2 the bond order of both the species for C-C is find to be equal i.e 3.
- As, for finding the C-C bond order CaC2 written as C2-2 and also C2H2 will be written as C2-2.
- As, in C2-2 there are 14 e's . So, the filling will takes place like σ1s² σ*1s² σ2s² σ*2s² σ2pz² π2px²= π2py².
- As, bond order formula ,
B.O = Bonding e's - Anti-bonding e's /2
= 10-4/2 ,
= 3.