Bond Order Definition: Bond order is a measurement of the number of electrons involved in bonds between two atoms in a molecule.
Most of the time, bond order is equal to the number of bonds between two atoms. Exceptions occur when the molecule contains antibonding orbitals.
Bond order is calculated by the equation:
Bond order = (number of bonding electrons - number of antibonding electrons)/2
If bond order = 0, the two atoms are not bonded.
Examples: The bond order between the two carbons in acetylene is equal to 3. The bond order between the carbon and hydrogen atoms is equal to 1.