Which statement correctly describes the magnetic properties of nitrogen gas (N2) and oxygen gas (O2) as given?

Which statement correctly describes the magnetic properties of nitrogen gas (N2) and oxygen gas (O2) as given?

• A. N2 is paramagnetic; O2 is diamagnetic
• B. N2 is diamagnetic; O2 is paramagnetic
• C. Both are diamagnetic
• D. Both are paramagnetic

Answer: (B)

Magnetic behavior comes from whether a molecule has unpaired electrons. If all electrons are paired, the substance is diamagnetic; it’s weakly repelled by a magnetic field. If there are unpaired electrons, it’s paramagnetic and is attracted to a magnetic field. For nitrogen gas, the electrons fill the molecular orbitals with all spins paired, so there are no unpaired electrons. That makes N2 diamagnetic. For oxygen gas, two electrons occupy the antibonding π* orbitals with unpaired spins, giving two unpaired electrons. That makes O2 paramagnetic. So the best description is that nitrogen is diamagnetic and oxygen is paramagnetic.

Magnetic behavior comes from whether a molecule has unpaired electrons. If all electrons are paired, the substance is diamagnetic; it’s weakly repelled by a magnetic field. If there are unpaired electrons, it’s paramagnetic and is attracted to a magnetic field.

For nitrogen gas, the electrons fill the molecular orbitals with all spins paired, so there are no unpaired electrons. That makes N2 diamagnetic. For oxygen gas, two electrons occupy the antibonding π* orbitals with unpaired spins, giving two unpaired electrons. That makes O2 paramagnetic.

So the best description is that nitrogen is diamagnetic and oxygen is paramagnetic.