Bond Order

The Bond Order calculator computes the bond order based on the number of bonding and antibonding electrons.

INSTRUCTIONS: Enter the following:

• (a) Antibonding Electrons
• (b) Bonding Electrons

Bonding Order (BO): The calculator returns the bonding order as a real number.

The Math / Science

The Bond Order formula, Bond Order = [(number of bonding electrons) - (number of anti-bonding electrons)] / 2, is used to determine the stability of a molecule or ion. This equation is derived from Molecular Orbital Theory and indicates the strength of a bond. Increasing bond orders are associated with increasing bond energy and decreasing bond length. An odd value for the bond order indicates that the molecule or ion contains an odd number of electron, such as nitrogen monoxide, and is paramagnetic. The inputs are the number of electrons in an antibonding molecular orbital, and the number of electrons in a bonding molecular orbital. There are no units for this equation.

The formula for the bond order is:

    BO =(("bonding":"electrons") - ("antibonding":"electrons"))/2

Example

Hydrogen gas (H₂) has a bond order of 1 between the two hydrogen atoms.

Lewis Structure

H:H

There is only one bond between the two atoms, which indicates a bond order of 1. 

However, if we wanted to use the formula:

Bonding electrons: 2

Antibonding electrons: 0

2-0/2 = 1

Supplemental Material

ChemWiki: Bond Order and Lengths

References

Whitten, et al. "Chemistry" 10th Edition. Pp. 335

Wikipedia: Bond Order