Question

Which the following molecules/species have identical bond order and same magnetic properties ?

(I) O2+ ; (II) NO; (III) N2+

• A. (I) , (II) only
• B. (I) and III only
• C. (I) ,(II) and (III)
• D. (II) and (III) only

Answer 1

Answer: (C)

(I) ,(II) and (III)

Answer 2

(I) O2+ : ($\sigma$1s)2 ($\sigma$ *1s)2 ($\sigma$2s)2 ($\sigma$ *2s)2 ($\sigma$2pz)2

($\pi$2p2x = $\pi$2p2y ) ($\pi$ *2px1 = $\pi$ *2p0y)

Bond order = 1/2(10 – 5) = 2.5.

(II) NO is derivative of O2 and isoelectronic with O2+ :

so ($\sigma$1s)2 ($\sigma$ *1s)2 ($\sigma$2s)2 ($\sigma$ *2s)2 ($\sigma$2pz)2

($\pi$2p2x = $\pi$2p2y ) ($\pi$ *2px1 = $\pi$ *2p0y)

Bond order = 1/2(10 – 5) = 2.5.

(III) N2+ : ($\sigma$1s)2 ($\sigma$ *1s)2 ($\sigma$2s)2 ($\sigma$ *2s)2

($\pi$2p2x = $\pi$2p2y ) ($\sigma$2pz)1

Bond order = 1/2(9 – 4) = 2.5.

O2+ , NO and N2+ have same bond order i.e. 2.5 and have same magnetic property having one unpaired electron.