[Chemistry Class Notes] on Bond Order Formula Pdf for Exam

Chemistry is concerned with the process through which subatomic particles combine to form atoms. Bond order is critical in molecular orbital theory for determining bond strength and is also used in valence bond theory. 

The bond order of a molecule is a measure of the number of electrons participating in bonds between two atoms. It is used to determine the stability of a connection. 

Concept of Bond Order

The bond order concept was first introduced by Linus Pauling. The disparity between the number of bonds and antibonds is what defines it.

The bond number is the number of electron pairs that exist between two atoms. The higher the bond order, the more powerful the bond. 

Bond order is often sufficient for the number of bonds between two atoms. There are exceptions when a molecule comprises antibonding orbitals.

It is the measure of the stability of the molecule. The stability of the molecule also depends on the type of bonds. The electronic configuration of the atoms determines the bond order. There is a well-established bond order formula to calculate bond order. It is important to study the formula to find bond order to look into the structure of different compounds and calculate their stability. Let us learn more about bond orders in this chapter.

The bond order of a single covalent bond between two atoms is one, a double bond is two, a triple bond is three, and so on.

Follow these methods to discover the bond order between two covalently bonded atoms:

Create a Lewis structure.

Determine the nature of the bonds that exist between the two atoms.

0: No bond exists.

1: Single bond

2: double bond

3: triple bond

The molecule cannot form if the bond order is zero. Higher bond orders suggest that the new molecule will be more stable.

The bond order in molecules with resonance bonding does not have to be an integer.

Bond Formula – Structure

The average bond order formula considers the number of electrons on the bonding and the antibonding orbitals. It is defined as half of the difference between them. The bond order equation is

Bond order =[frac{1}{2}[N_{b}-N_{a}]]

Where Nb is the number of electrons in the bonding orbitals

And Na is the number of electrons in the antibonding orbitals.

A simpler way to find the bond order is to calculate the number of bonds between the atoms. For example, for N≡N, the bond order is 3.  

Bond Order – Reaction

How is a Bond Order Determined in a Chemical Reaction?

In a chemical reaction between two atoms, the bond order is determined by the number of electrons participating in bond formation. The atoms can interact to form covalent or ionic bonds. In Ionic bonds, electrons are transferred from one atom to another. Covalent bonds involve the sharing of electrons between two atoms. 

The electronic configuration of the atoms determines the bond order. For example, in a Carbon molecule, four bonds are shared between the two carbon atoms. Both the carbon atoms require four electrons to complete their octet. Therefore, the bond order in a carbon molecule is 4. Similarly, the bond order for nitrogen molecules is 3 and oxygen is 2.

Example:

The s shell of hydrogen atoms has one electron, and the s shell can accommodate two electrons. 

When two hydrogen atoms form a bond, each completes the other’s shell. There are two bonding orbitals generated. 

There are no electrons compelled to migrate to the next higher orbital, the p shell, resulting in the formation of antibonding orbitals. 

The bonding order = Display style (2-0)/2 = 1, is the bonding order. Hence, the molecule H₂ (hydrogen gas) is formed as a result of this reaction.

What is the Importance of Bond Order?

It is important to study the bond order formula in chemistry. It helps us to understand several factors contributing to the formation of the compound. Some of them are:

Bond order helps us to know the number of participating electrons in the formation of bonds.

• Bond order helps us to understand the stability of the bond. Higher bond order confers more stability.

• Bond order helps us to understand the bond length.

• Bond order helps us to understand bond strength. Higher bond order implies more energy is required to break the bond.

• Bond order gives us an indication of the hybridization of the molecule.

• A fractional bond order value implies that no bond is formed.

Conclusion

The concept of bond order has been studied for several years. Bond order is determined by the number of bonding and antibonding electrons. People use the bond order formula to find out the bond. Various properties of the bond can be known from bond order values.