Enter the covalent radii of two atoms and the electronegativity of each atom into the calculator to determine the bond length.

## Bond Length Formula

The following formula is used to calculate a bond length.

dA-B = rA + rB – .09 * (xA – xB)

- Where dA-B is the distance between the nuclei of atoms A and B
- rA is the covalent radius of atom A
- rA is the covalent radius of atom B
- xA is the electronegativity of atom A
- xB is the electronegativity of atom B

## Bond Length Definition

**What is a bond length? **A bond length is a measure of the distance between the centers of two bonded nuclei. The distance is typically measured in picometer.

## Example

How to calculate bond length?

**First, determine the lengths of the covalent radii.**For this example, the radius of atom A is 24 picometers and the radius of atom B is 32 picometers.

**Next, determine the electronegativity of atom A.**For this problem, atom A has an electronegativity of 3.2.

**Next, determine the electronegativity of atom B.**The electronegativity of atom B is found to be 2.1.

**Finally, calculate the bond length.**Using the formula above, the bong length is found to be dA-B= 24+32-.09*(3.2-2.1) = 55.901.

## About Bond Length

**Is bond length an average? **In general, when calculating a bond length, the resulting answer is an average length between nuclei.

**How does bond length change with bond order? **As bond order increases, the bond length will decrease. For example, a third bond order will have a smaller bond length than a second bond order.