Question

The bond order in NO is 2.5 while that in NO+ is 3. Which of the following statements is true for these two species?

• A. Bond length in NO+ is greater than in NO
• B. Bond length in NO is greater than in NO+
• C. Bond length in NO+ is equal to that in NO
• D. Bond length is unpredictable

Answer 1

Answer: (B)

Bond length in NO is greater than in NO+

Answer 2

NO and NO+ are derivative of O2.

NO(isoelectronic with O2+) : ($\sigma$1s)2 ($\sigma$ *1s)2 ($\sigma$2s)2

($\sigma$ *2s)2 ($\sigma$2pz)2 ($\pi$2p2x = $\pi$2p2y ) ($\pi$ *2px1 = $\pi$ *2py)

Bond order = 1/2(10 – 5) = 2.5.

NO+(isoelectronic with O22+) : ($\sigma$1s)2 ($\sigma$ *1s)2 ($\sigma$2s)2 ($\sigma$ *2s)2 ($\sigma$2pz)2 ($\pi$2p2x = $\pi$2p2y ) ($\pi$ *2px = $\pi$ *2py)

Bond order = 1/2(10 – 4) = 3.

Bond order $\propto$ 1/bond length.

So NO+ has shorter bond length.