Bond Order Calculator
Compute molecular-orbital bond order from the number of bonding and antibonding electrons — and see whether the species is stable or paramagnetic-friendly.
How it works
Bond order = (bonding electrons − antibonding electrons) ÷ 2
In molecular-orbital theory, electrons in bonding orbitals hold atoms together while electrons in antibonding orbitals push them apart. The bond order is half the net bonding electrons, and it lines up with the classical idea of single, double and triple bonds: O₂ works out to 2, N₂ to 3. A bond order of zero or below means the destabilising electrons cancel the bonding ones, so the species is not expected to exist as a stable molecule.
Worked example
Molecular oxygen O₂ has 10 electrons in bonding orbitals and 6 in antibonding orbitals. Bond order = (10 − 6) ÷ 2 = 2, a double bond — consistent with O₂’s known chemistry.
Sources: Bond order — Wikipedia
Frequently asked questions
Can bond order be a fraction?
Yes. Odd-electron species like the O₂⁺ ion or NO have half-integer bond orders such as 2.5. A fractional bond order simply reflects an unpaired electron in the molecular-orbital diagram.
What does a bond order of zero mean?
It means bonding and antibonding electrons exactly cancel, so there is no net bond. He₂ has a bond order of zero, which is why helium does not form a diatomic molecule.
How does bond order relate to bond strength?
Higher bond order generally means a shorter, stronger bond. A triple bond (order 3) like N₂ is shorter and stronger than a double bond (order 2) like O₂.
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This calculator is for educational purposes. Double-check important results before acting on them.