Bond Order

In the simple Lewis-structure picture, bond order is just the NUMBER of shared electron-pair bonds linking two atoms in a molecule — 1 for a single bond (H2), 2 for a double bond (O2), 3 for a triple bond (N2) — and this Lewis-theory bond order matches exactly the bond order computed from molecular-orbital electron counts (section 5.5.6's worked H2/N2/O2 examples). ISOELECTRONIC molecules or ions — species sharing the same TOTAL electron count — always share an identical bond order as a direct consequence: N2, CO and NO⁺ each have exactly 14 electrons and each therefore has bond order 3. Bond order is a strong, general predictor of a molecule's relative stability: AS BOND ORDER INCREASES, bond enthalpy increases and bond length decreases — tying …