Read Unpaired Electrons Before Calling a Species Paramagnetic
Magnetic behaviour reads directly off the same MO electron-filling diagram used for bond order — any unpaired electron in the highest occupied orbitals makes the species paramagnetic, and only complete pairing gives diamagnetism.
Electricity questions depend on identifying charge, a conducting path and the condition that controls current or magnetic effect.
O2's paramagnetism is the classic MOT success story
O2 is paramagnetic with 2 unpaired electrons in its degenerate π* orbitals — Lewis structures can't explain this, but simple MOT filling order predicts it immediately, which is exactly why this fact anchors so many MOT questions. Adding electrons to reach O2- (1 unpaired) then O2²⁻ (0 unpaired, diamagnetic) shows pairing happening step by step in those same π* orbitals.
Ions of the same neutral molecule can flip magnetic character entirely
N2 itself is diamagnetic (all electrons paired), but both N2+ and N2- pick up one unpaired electron each — removing OR adding an electron to a fully-paired diatomic typically creates paramagnetism, since you can't remove/add just one electron without leaving an odd one out somewhere.
Species with identical bond order don't always have identical magnetism
Two species can share the same bond order while differing in unpaired-electron count if their electrons are distributed across different orbital sets — don't infer magnetic behaviour from bond order alone; always go back to the actual electron filling for that specific species.
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- ✓Any unpaired electron in the MO diagram makes a species paramagnetic; complete pairing gives diamagnetism.
- ✓O2 is paramagnetic (2 unpaired in π*); O2- has 1 unpaired; O2²⁻ has 0 (diamagnetic) — pairing happens stepwise.
- ✓Adding or removing one electron from a diamagnetic diatomic (like N2) typically creates an unpaired electron, making the ion paramagnetic.
- ✓Equal bond order does not guarantee equal magnetic behaviour — check the actual electron distribution for each species.
Don't assume two species with the same bond order must have the same magnetic behaviour — bond order only counts net bonding electrons, while magnetism depends on exactly how electrons are distributed (paired or unpaired) across the orbital set.
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