The pairs of species of oxygen and their magnetic behaviours are noted below. Which of the following presents the correct description?
- O2-, O22- – Both diamagnetic
- O2+, O2 – Both paramagnetic
- O, O22- – Both paramagnetic
- O+, O22- – Both paramagnetic
Answer
(2) O2+, O2 – Both paramagnetic
Solution
O2 (16 e⁻): *2px1 *2py1 ⇒ 2 unpaired electrons – paramagnetic
O2+ (15 e⁻): *2px1 ⇒ 1 unpaired electron – paramagnetic
O2- (17 e⁻): 1 unpaired electron – paramagnetic
O22- (18 e⁻): *2px2 *2py2 ⇒ no unpaired electron – diamagnetic
O atom (2s2 2p4): 2 unpaired electrons; O+ (2s2 2p3): 3 unpaired electrons
∴ Only the pair O2+, O2 – both paramagnetic – is correctly described.
Answer: (2)