Question

The MO diagram of CN is similar to N2. Based on the molecular orbital energy-level diagram of CN, which of the following statements are correct?
i. The CN bond order is 2.
ii. CN is diamagnetic.
iii. The bond enthalpy in CN- ion is higher than CN.
iv. CN has longer bond length than CN-

answer choices:
a. ii, iv
b. iii, iv
c. i, iii
d. i, ii
e. i, iv

Answer 1

Answer:

Nitrogen molecule (N2)

The electronic configuration of nitrogen (Z=7) = 1s2 2s2 2px12py12pz1.

The total number of electrons present in the nitrogen molecule (N2) is 14.

In order to maximize energy, these 14 electrons can be accommodated in the different molecular orbitals.

N2: KK'(σ2s)2 (σ*2s)2 (π2Px)2 (π2py)2 (σ2pz)2

Here (σ1s)2 (σ*1s)2 part of the configuration is abbreviated as KK’, which denotes the K shells of the two atoms. In calculating bond order, we can ignore KK’, as it includes two bonding and two antibonding electrons.

The bond order of N2can be calculated as follows:

Here, Nb = 10 and Na = 4

Bond order = (Nb−Na) /2

B.O = (10−4)/2

B.O = 3

So your answer should be C3.