How to Calculate Bond Order

Bond Order Definition Chemistry - Bond order determines the bonding in the molecule. It is responsible for the stability of the molecule or ion. Higher bond order means the bond is strong, which means the bond energy is higher.

For a diatomic molecule, a greater bond order means the bond length is short. According to valence bond theory, bond order is the number of bonded electron pairs between two atoms. According to the molecular orbital theory, it equals the difference between the number of bonding and antibonding electrons divided by 2. 

To calculate the bond order, you add all the bonding pairs and divide them by the total number of bonds. For diatomics, the bond order can be single, double or triple.

For example, hydrogen has two electrons in the bonding orbitals and zero in the antibonding orbital, so the bond order is 1 [B.O. = 0.5(2-0) = 1]. Therefore, the bond order of H2O is 2, and NH3 is 3. 

What is Bond Order?

Bond order is the number of bonds or shared pairs of electrons between two atoms. It is a relatively straightforward concept where the bond order gives the number of bonds between two atoms in a molecule. 

Now, hydrogen and hydrogen share one pair of electrons. Therefore, they have a single covalent bond. Therefore, hydrogen has a Bond Order of 1. On the other hand, the oxygen molecule, O2, has two pairs of electrons. Therefore, it has a double covalent bond. 

Therefore, bond order is the number of shared pairs of electrons or bonds between atoms. 

For example - the bond order of the fluorine molecule is one. This is because each fluorine atom has 7 electrons in its outermost cell, and to complete the octet; it needs to form one bond.

Therefore, the fluorine molecule is formed by sharing one pair of electrons between the two Fluorine, resulting in a single bond. Hence, the Bond Order is 1.

In the molecular orbital theory, you calculate the bond order using functions which describe the state of electrons and the functions are called orbitals. Orbitals represent the locations of the electrons in the electron cloud represented by the letters – s,p,d,f.

The shape and size of the orbital changes for each letter, where s has a sphere shape, and p has a figure of eight. The structure is also distinguished based on the bonding, non-bonding orbitals, antibonding and geometry of the bond. 

One must determine the number of electrons in the valence shell and the block the molecule belongs to. The element's group (except helium) for block s identifies the number of electrons in the valence shell.

For block p, the number of electrons in the valence shell equals the group minus ten. Unfortunately, no straightforward method exists to check the electrons that fill orbitals in blocks d and f. 

What is the Formula of Bond Order? Explain with an Example.

Many theories are related to bond orders, and many different types of calculations are used for determining the bond order. For example, the bond order's magnitude directly relates to bond length. The Linus Pauling formula determines the bond order between atoms.

Linus Pauling explained electronegativity as the power of the atom in a molecule to attract electrons. The electronegativity of an atom is the relative value of its ability to attract electron density towards itself when it creates a bond with another atom.

The higher the electronegativity, the more the atom can pull electrons towards it and away from any atom with which it forms a bond. The main properties of the atom show that its electronegativity is its atomic number as well as the atomic radius. 

The electronegativity tends to increase as it moves from left to right and bottom to top across the periodic table, which means the electronegativity of Fluorine is highest, and the least electronegativity is of Francium. 

Pauling explains the phenomena of electronegativity and describes how the bond energies are related. He explains the degree or order of bonding between two atoms cannot just be determined through analysis of the molecular wavefunctions; it can also be estimated using the bond distance and the bond order correlation.

The empirical scheme is useful for comparing the data and has some value as a postfactum. The approach is based on the assumption that the bond order varies exponentially with bond distances.

Bond Order Formula:

Let's check how to find out the bond order. First, there is a formula for calculating the Bond Order. 
Bond Order = ½ [ number of bonding Electrons - number of Antibonding Electrons ].

Nb denotes the number of bonding electrons, and
Na denotes the number of antibonding electrons.

Let's see how this formula will help determine the bond order.

• Suppose you have to find the bond order for hydrogen gas with the help of this formula.

• To find out the bond order of the hydrogen gas, follow the steps mentioned in the section below.

Step 1. 

In the first step, you have to write down the electronic configuration of the hydrogen atom. For example, the electronic configuration of the hydrogen gas is (σ1s)2.

Step 2. 

In the next step, you must enter the values in the formula. By entering the value in the formula, you will get 
Bond Order = ½ [2-0] = 1.

Here, the number of bonding electrons is two, and the number of antibonding electrons is 0.

Hence, the Bond Order of the hydrogen gas is 1, and no unpaired electrons are present in the hydrogen gas.

How To Calculate Bond Order From Lewis Structure?

Bond order is calculated from the Lewis structure, which is the key to the valence bond model. For example, the bond order of Sulfur dioxide is 1.5 as the average of an S-O single bond in one Lewis structure, and a S=O double bond in another is used to get the average. 

The molecular orbital theory calculates the bond orders where you can assume two electrons in a bonding molecular orbital that contributes one net bond and the two electrons in an antibonding molecular orbital that cancels the effect of one bond. 

Both molecular orbital theory and Lewis structure lead to the same bond order, and there are some differences between the two models. For example, the electrons in the Lewis structure are paired, and there are two unpaired electrons in the molecular orbital description of the molecule. 

The atoms or molecules in which the electrons are paired are diamagnetic, and there can be one or more unpaired electrons which can be paramagnetic, those that are attracted to the magnetic field. The molecular orbital model of O2 is often better than the valence–bond model.

Can You Measure Bond Order?

To calculate bond order, you must know the number of bonding orbital and antibonding electrons. Bond order is the metric used to measure the stability of a bond. It can be changed through the bond order drop-down menu.

For example, to measure bond order (BO), you need to know the bonding electrons and deduct the antibonding electrons from several bonding electrons = (Nb- Na).

One can use the Lewis structure to estimate bond order through the valence–bond model. For example – Oxygen has a bond order of two. If there is more than one Lewis structure for a molecule, the average of the structures determines the bond order. 

Q. What is the Bond Order of CO, N2, NO+?

F2 and O22− have bond order 1, while N2, CO and NO+ have bond order 3.

Q. What Is The Bond Order F2+?

 The bond order of F2+ is 1

Q. How to Find the Bond Order of O2?

How To Measure Bond Order -  

Electronic configuration of oxygen atom - 1s² 2s² 2p?
Atomic orbitals of oxygen join to form molecular orbitals.
Bond order in an Oxygen molecule (O2)
=½ (number of bonding electrons)–(number of anti−bonding electrons)
= ½ 10–6
= 2

In molecular orbital theory, one can estimate bond orders by assuming the two electrons in the bonding molecular orbital add one net bond. Then two electrons in an antibonding molecular orbital cancel the effect of one bond. 

Bond Order = Bonding Electrons - Antibonding Electrons/ 2 = 8-4/2 = 2

How to Find Bond Order of O2?

How to find the bond order of O2 to calculate the bond order of O2.

Bond order (B.O) 1/2 × [number of an electron in antibonding molecular orbitals] – [number of electrons in bonding molecular orbitals]
(1) B.O for O2 = 1/2 × [10 – 6]
B.O for O2 = 2
(2) B.O for O2– = 1/2 × [10 – 7]
B.O for O2– = 1.5
(3) B.O for O2+ = 1/2 × [10 – 5]
B.O for O2+ = 2.5
(4) B.O for O22- = 1/2 × [10 – 8]
B.O for O22- = 1
∴ The increasing order of bond length for these species is
O2+< O2 < O2– < O22-

What is F2 Bond Order? 

Bond order of f2+ This halogen interacts with metals and creates salts, including sodium and fluoride. 
F contains 7 Valence electrons.
The Bond order for F2 is 1.

To discover the cumulative electrons in bonding (Nb) and maximum antibonding (Nb), we must analyse or report the structure through the diagram of the F2 molecular orbital. 

• In terms of maintaining cohesion, you require 1/2(number of bonding electrons - no of anti-monopolistic consequently; F2+, F2.So, F2+>F2);

• Second, F2's electron structure seems to be (sigma 2s)^2. (sigma 2s*)^2. (sigma 2px)^2. (pi 2py)^2.

Using this expression as the aforementioned: Bond Order = Bond Order = [(number of electrons in bonding molecules) - (number of electrons in antibonding molecules)]/2.

What is the Bond Order of CO? 

CO's bond order is 3. There is a triple bond between C and O in carbon monoxide CO. Two are covalent bonds formed by sharing electrons between carbon and oxygen. The third bond is a non-covalent bond formed when C acquires a lone pair of electrons from O.

• For instance, the bond order of diatomic N N≡N is 3, the bond order of acetylene H−C≡C−H is always 3, and each bond order is C-H 1. 

• The Bond Order is defined in the molecular orbital theory as half the difference between the bonding elements and the number of antibonding electrons. 

What is a Bond Order Calculator?

If we have several electrons as 14, its bond order will be 3. The trick is if we increase the number of electrons or decrease the number of the electron, the bond order decrease by one. 

• For 16 electrons, the bond order will be 2; for 12 electrons, the bond order will be 2. 

• If you increase the electron 2, the 18 electrons' bond order is one and for the 10 electrons, we all have the bond order is one. So you have to focus on the 14-electron species. 

• If it increases the electron by two or decreases the electron by two, the bond order will decrease by one. So now, if you go for 20 electrons, the bond order will be 0. 

• Similarly, for 8 electrons, the bond order becomes 0. If the number of electrons is less than eight, the formula for bond order is (1/2) {the number of electrons in bonding molecular orbital - the number of ABMO}. 

• This formula is a gentle trick to finding bond orders of elements.

Example -

Electronic configuration of C2 = (2s)2 (*2s)2 n(2px)2 n(2py)2
Step 2. From the above electron configuration, the values in the formula-
Bond order = (Nb – Na) / 2
=( 8 – 4 )/ 2
= 2

What is Bond Order N2?

The electronic configuration of N-atom(Z=7) is 1 s to the power of 2 space end exponent 2 s squared 2 p subscript x superscript 1 2 p subscript y superscript 1 2 p subscript z superscript 1. The total number of electrons present in the N2 molecule is 14.

Determine the bond order for the n2+ ion; the N2+ ion is formed by losing one electron from the N2 molecule. This lost electron will be lost from the (2pz) orbital. Hence, the electronic configuration of N2+ ion will be N2+ = KK[(2s)]2 [*(2s)]2 [(2px)]2 [(2py)]2 [(2pz)]1
Here, Nb =7, Na=2 so that bond order of N2 =Nb-Na/2=8-2/2=3.

What Are Chemical Bonds?

Chemical bonds are building blocks to another inside a compound, and they are called intra-bonds, and some of these attract one compound to another and are called inter-bonds. Electrons carry a negative charge and control all types of bonds. Electrons are three primary sub-atomic particles that make an atom.

Electrons move in a way to create electrically positive and negative zones. Negative areas attract positive areas and vice versa. 

Non-metal atoms gain electrons when the metals lose, and the non-metals become negatively charged. The charged particles are known as ions. The attraction of a positive ion to a negative ion forms an ionic bond, creating an ionic compound. 

The intra-bond type 2 is a covalent bond which doesn't transfer an electron from one atom to another, and such a shared pair of electrons is a covalent bond. Water is one of the examples of a compound formed by covalent bonds. 

Inter bonding attracts a molecule to another to form covalent molecules and such attractions between molecules are called intermolecular forces. 

How To Calculate Bond Order in Resonance Structures?

Bond order is the number of bonding pairs of electrons between two atoms, and in a covalent bond between two atoms, a single bond has a bond order of one. A double bond has a bond order of two, and a triple bond has a bond order of three, and so on. 

Resonance comes under the Valence Bond Theory of bonding, which describes the delocalisation of electrons within molecules. It sometimes involves constructing multiple Lewis structures that, when combined, represent the full electronic structure of the molecule. 

The bond length is dependent on the atomic radius of two bonded atoms in the structure, and for resonating structures, the extremes are averaged for a better view of bonding. 

In the case of SO3 – It contains one double bond and two single bonds and so the bond order of the SO3 resonance structure is 1.33 and not 2.

Similarly, the bond order of NO2 is 1.5, which is determined by dividing the number of electron pairs in N-O bonds by the total number of N-O bonds. 

Suppose you want to know if there are three double covalent bonds between sulphur and oxygen atoms in each molecule of sulphur trioxide. The structure of sulphur trioxide is a trigonal planar there; you may not get a lone pair on the core element sulphur due to a double bond. So there can be three resonance structures possible for the sulphur trioxide.

How to Calculate Bond Order?

Bonds hold the universe together, and they determine the structure of substances. Some materials are soluble, and some may serve as lubricants because of bond properties, and the bonds also determine the electrical conductivity in any substance.

The bond order tells how many chemical bonds are present in a pair of atoms and the number of electrons involved in bond formation between two molecule atoms. It shows the number of chemical bonds present in a pair of atoms. The number of bonding electrons minus the number of antibonding electrons determines the bond order.

In molecular orbital theory, bond length, strength, order, and magnetic properties of different molecules play an important role in keeping the structure of a substance together. Bond order is the bonding pairs between two atoms.

Therefore, one can calculate the bond order of any molecule by creating a molecular orbital diagram, like you may have to calculate the bond order in h−2 ion. 

The bond order represents the number of chemical bonds between two atoms. So if there is one bond between two atoms, the bond order is one. For example, the bond order of the CO molecule is 3. 

CO has a bond order of three, and the bond order indicates the number of bonds that exists between two atoms. So the difference between the number of bonds and anti-bonds is defined by Linus Pauling. 

The number of electron pairs or covalent bonds between two atoms represents the bond number. For example, the bond number in the diatomic nitrogen NN is 3, the bond number between two carbon atoms in ethyne HCCH is 3, and the CH bond order is 1. 

There are many other ways you determine the bond orders, like the bond number may not be an integer in molecules with resonance or nonclassical bonding. For example, the delocalised molecular orbitals of benzene contain six pi electrons over six carbons, generating half a pi bond with the sigma bond for each pair of carbon atoms that yields a computed bond number of 1.5.

To create the molecular diagram, you can start with the orbital diagram for both atoms, focusing on the valence electrons.

Linus Carl Pauling introduced the theory of resonance of molecules among two or more valence bond structures based on the interchange of energy of two electrons for treating bond hybridisation.

In resonance, the true state of a chemical system is neither of the component quantum state but an intermediate caused by the interaction that reduces the energy making the actual normal state of the molecule stable.

Therefore, understanding the difference between the number of bonds and anti-bonds in an atom is necessary to determine the bond order to estimate the bond strength. Furthermore, how tightly the bonds are associated or bonded to each other and how affected the overlap is between the different atoms determines the stability of the structure. 

Another important aspect of the molecular orbital theory is the bond length. It is important to understand that the bond length and bond strength are inversely proportional to each other. 

If the bond strength is very high, that means the bonds are closer to each other. Conversely, bonds are farther apart if the strength or overlap is weak.

Now, what is bond dissociation energy? The bond dissociation energy means an amount of energy that is required to break that bond. 

It is noticeable that bond strength is related to the bond dissociation energy. Hence, the higher bond is related to the stronger and shorter bonds. 

If the bond length decreases with the increase of the bond order and vice-versa.

How to Determine the Bond Length?

Bond length is the internuclear distance between two bonded atoms. dA-B = RA + RB – 0.09 (xA – xB). This is the formula for bond length. 

rA means the radius of, and RB means the radius of b. XA means electronegativity of A, and XB means electronegativity of the element B. 

If electronegativity decries, the bond size also increases basically. In a nutshell, if electronegativity increases, the bond length decreases. So we can relate electronegativity to atomic size also. 

Suppose you have a carbon size of x and a silicon size of y. So mathematically, the size of y or the value of y is greater than x. 

Bond length is a function of bond length. Bond length is inversely propositional to bond angle. If the bond angle is more, then that bond length is small, and if the bond angle is small, then the bond length is large. 

That is why this relationship comes into blink. Bond energy is directly propositional to Bond Order. So if the bond length increases, we have to provide less energy, meaning bond energy will be inversely propositional to bond length. 

And if the bond size is increasing hence, the bond energy will decrease. There is an exception in the 3rd periodic table elements because of a vacant orbital.

2>1>3>4 This will be the order of bond energy of the 3rd periodic table.

What is a Shortcut? How to Find the Bond Order of any Molecule?

The bond order is just a number that describes how effective the correlation between these two atoms that comprise a molecule seems to be. 

When the B.O. becomes strong, the molecule remains stable. Therefore, it implies that B.O influences molecule equilibrium. 

And here's a formula for the Bond Order calculation: 

• BondOrder=12(Nb–Na)BondOrder=12(Nb–Na) 

• In which, Nb = Bonding M.O. No of electrons. 

• As well as Na = Antibonding M.O. Electrons No. 

Conclusion:- 

The sequence of bonds seems to be the sum of electron-paired bonding between two atoms. When hydrogen atoms bond covalently to electronegative atoms, like nitrogen, Fluorine or oxygen, then large dipoles are created. The intermolecular dipole attraction is the same as described above, called the hydrogen bond.

In some cases, the electrons may move around within bonds for reasons other than differences in electronegativity. For example, when one molecule approaches the other, the electrons within the covalent bonds of the two molecules repel one another. As a result, it creates the same δ+ and δ- charges.

Bond orders can be calculated from Lewis structures like in oxygen, which has a bond order of two. The bond order averages these structures when there is more than one Lewis molecule structure. 

Although Lewis structure and molecular orbital models may yield the same bond order, for example, the electrons in the Lewis structure are all paired in the case of oxygen. There are two unpaired electrons in the molecular orbital description of the molecule.

We can predict the theories by studying the effects of a magnetic field on elements like oxygen. Paired atoms are diamagnetic, and both poles of a magnetic field repel them. Those with one or more unpaired electrons are paramagnetically attracted to a magnetic field.