Bond Order Calculation

Bond order is the number of chemical bonds between a pair of atoms. It is the difference between the number of bonding electrons and antibonding electrons. The bond order is a measure of the stability of the molecule. If the bond order is high, the molecule is stable, and if it is low, the molecule is unstable.

Steps to calculate Bond Order

1. Draw the Lewis structure of the molecule.
2. Count the number of electrons in the molecule.
3. Determine the number of bonding electrons.
4. Determine the number of antibonding electrons.
5. Calculate the bond order.

Bond Order Calculation Examples

Example 1: H2

1. Draw the Lewis structure of the molecule.

H:H

2. Count the number of electrons in the molecule.

Each hydrogen atom has one electron, so the molecule has two electrons.

3. Determine the number of bonding electrons.

There is one bond between the hydrogen atoms, and each bond contains two electrons. Therefore, there are two bonding electrons.

4. Determine the number of antibonding electrons.

There are no antibonding electrons.

5. Calculate the bond order.

Bond order = (Number of bonding electrons – Number of antibonding electrons) / 2

Bond order = (2 – 0) / 2

Bond order = 1

The bond order of H2 is 1.

Example 2: O2

1. Draw the Lewis structure of the molecule.

O=O

2. Count the number of electrons in the molecule.

Each oxygen atom has six electrons, so the molecule has 12 electrons.

3. Determine the number of bonding electrons.

There is one bond between the oxygen atoms, and each bond contains two electrons. Therefore, there are four bonding electrons.

4. Determine the number of antibonding electrons.

There are four antibonding electrons.

5. Calculate the bond order.

Bond order = (Number of bonding electrons – Number of antibonding electrons) / 2

Bond order = (4 – 4) / 2

Bond order = 0

The bond order of O2 is 0.

Example 3: N2

1. Draw the Lewis structure of the molecule.

N≡N

2. Count the number of electrons in the molecule.

Each nitrogen atom has five electrons, so the molecule has 10 electrons.

3. Determine the number of bonding electrons.

There is one triple bond between the nitrogen atoms, and each bond contains two electrons. Therefore, there are six bonding electrons.

4. Determine the number of antibonding electrons.

There are four antibonding electrons.

5. Calculate the bond order.

Bond order = (Number of bonding electrons – Number of antibonding electrons) / 2

Bond order = (6 – 4) / 2

Bond order = 1

The bond order of N2 is 1.