Question

An odd electron molecule among the following is (2015)

• A. CO
• B. SO$_2$
• C. CO$_2$
• D. NO
• E. O$_2$

Hint:

Common odd electron molecules to remember: NO, NO$_2$, ClO$_2$. They are typically paramagnetic.

Answer 1

The Correct Option is D

To determine which molecule is an odd electron molecule, we need to analyze the electronic configuration and the number of electrons in each option provided:

1. Carbon Monoxide (CO):
   • Carbon (C) has 6 electrons and Oxygen (O) has 8 electrons.
   • Total number of electrons in CO: 6 + 8 = 14 electrons.
   • All 14 electrons can be paired.
2. Sulfur Dioxide (SO₂):
   • Sulfur (S) has 16 electrons and each Oxygen (O) has 8 electrons.
   • Total number of electrons in SO₂: 16 + 8 + 8 = 32 electrons.
   • All 32 electrons can be paired.
3. Carbon Dioxide (CO₂):
   • Carbon (C) has 6 electrons and each Oxygen (O) has 8 electrons.
   • Total number of electrons in CO₂: 6 + 8 + 8 = 22 electrons.
   • All 22 electrons can be paired.
4. Nitric Oxide (NO):
   • Nitrogen (N) has 7 electrons and Oxygen (O) has 8 electrons.
   • Total number of electrons in NO: 7 + 8 = 15 electrons.
   • Here, one unpaired electron remains, making NO an odd electron molecule.
5. Oxygen (O₂):
   • Each Oxygen (O) has 8 electrons.
   • Total number of electrons in O₂: 8 + 8 = 16 electrons.
   • All 16 electrons can be paired although O₂ has high reactivity due to molecular orbital configuration but is not an odd electron molecule based on numbering criteria.

From the analysis above, it is clear that NO is the odd electron molecule. It has an unpaired electron in its molecular structure, which gives it unique chemical properties, such as being a radical.