Bond Order Calculator

What is a Bond Order in Molecular Orbital Theory?

Bond order shows the strength and stability of a chemical bond. It compares bonding electrons with antibonding electrons in molecular orbitals.

A higher bond order usually means a stronger and shorter bond. A bond order of zero means no stable conventional bond forms.

Bond Order in Molecular Orbital Theory

Molecular orbital theory uses bonding and antibonding electrons to calculate bond order. The formula subtracts antibonding electrons from bonding electrons, then divides by two.

$BO = (N_b - N_a) / 2$

Here, $N_b$ means bonding electrons and $N_a$ means antibonding electrons.

How to Calculate Bond Order Using Molecular Orbital Theory

Molecular orbital theory calculates bond order from bonding and antibonding electrons. Use this formula: $BO = (N_b - N_a) / 2$.

Formula

$BO = (N_b - N_a) / 2$

Step by step guide

1. Count the bonding electrons.
2. Count the antibonding electrons.
3. Subtract $N_a$ from $N_b$.
4. Divide the result by $2$.

Practical Example

For $N_2$, use 10 bonding electrons and 4 antibonding electrons.

$BO = (10 - 4) / 2 = 3$

Therefore, $N_2$ has a triple bond and strong bond stability.

How to Find Bond Order From a Lewis Structure

Lewis structures show bonds as shared electron pairs. You can find bond order by counting the bonds between two atoms.

Single, Double, and Triple Bonds

A single bond has a bond order of 1. A double bond has a bond order of 2. A triple bond has a bond order of 3.

Step by Step Method

1. Draw the Lewis structure.
2. Find the bond between the atoms.
3. Count the shared bond pairs.
4. Assign the bond order from the bond type.

Practical Examples

For $H_2$, the H to H bond is single, so $BO = 1$. For $O_2$, the O to O bond is double, so $BO = 2$.

How to Calculate Bond Order in Resonance Structures

Resonance structures can spread a bond across several equivalent positions. This can create a fractional average bond order.

Resonance Bond Order Formula

Use the total bond order across equivalent bonds: $Average\ BO = Total\ bond\ order\ units / Number\ of\ equivalent\ bonds$.

Step by Step Method

1. Draw all valid resonance structures.
2. Add the bond order units.
3. Count equivalent bonds.
4. Divide total units by equivalent bonds.

Practical Example

In ozone, $O_3$, one double bond and one single bond spread across two equivalent O to O bonds.

$Average\ BO = (2 + 1) / 2 = 1.5$

Bond Order, Bond Strength, and Bond Length

Bond order helps compare chemical bond strength and length. Higher bond order usually means stronger bonds with shorter bond lengths.

Bond Order and Magnetic Properties

Bond order and electron arrangement can help describe molecular magnetic properties. Unpaired electrons cause paramagnetism, while paired electrons cause diamagnetism.

Diamagnetic Molecules

Diamagnetic molecules have all electrons paired. For example, $N_2$ has bond order 3 and shows diamagnetic behavior.

Paramagnetic Molecules

Paramagnetic molecules contain one or more unpaired electrons. For example, $O_2$ has bond order 2 and shows paramagnetic behavior.

Bond Order Examples for Common Molecules and Ions