Short Answer

Bond order is directly related to bond strength. As bond order increases, the bond becomes stronger because more electrons are shared between the atoms. A single bond (bond order 1) is weaker, a double bond (bond order 2) is stronger, and a triple bond (bond order 3) is the strongest.

Higher bond order also means greater attraction between the bonded atoms, making the bond harder to break. Lower bond order results in weaker bonds that need less energy to break. Thus, higher bond order = higher bond strength.

Detailed Explanation :

Bond Order and Bond Strength

Bond order is an important concept in chemistry that tells us how many electron pairs are shared between two atoms. It helps describe the type of bond—single, double, triple—and gives insight into the stability and behaviour of molecules. Bond strength refers to how strongly the two atoms are held together, and how much energy is required to break the bond.

There is a clear and direct relationship: bond order increases bond strength. This connection is fundamental in understanding chemical bonding, molecular structure, and reaction patterns.

1. What Bond Order Means for Strength

Bond order indicates the number of shared electron pairs:

• Bond order 1 → single bond
• Bond order 2 → double bond
• Bond order 3 → triple bond

As more electron pairs are shared, the attraction between nuclei and electrons becomes stronger.
This increases bond strength because more energy is needed to pull the atoms apart.

Key idea:

Higher bond order means stronger bonding between atoms.

2. Why Higher Bond Order Increases Bond Strength

The connection exists because:

• More shared electrons create stronger electrostatic attraction.
• Shared electrons lie in bonding orbitals between nuclei, pulling atoms closer.
• Attractive forces overpower repulsive forces as bond order increases.

As a result:

• The bond becomes shorter.
• The energy needed to break the bond increases.

This is why triple bonds are the strongest type of covalent bonds.

Example:

• C–C single bond: relatively weak
• C=C double bond: stronger
• C≡C triple bond: strongest

Thus, increasing bond order increases bond strength.

3. Relationship Between Bond Order, Bond Length, and Bond Strength

Bond order affects not only strength but also length.

General trend:

• High bond order → short bond → strong bond
• Low bond order → long bond → weak bond

Reason:
A higher number of shared electrons pulls atoms closer, leading to stronger bonding.

Examples:

• Bond length decreases from single → double → triple.
• Bond strength increases in the same order.

This shows a combined relationship:

4. Bond Order in Resonance Structures and Its Effect on Bond Strength

In resonance structures, bond order may be fractional (e.g., 1.5 in benzene).
Even though fractional, it still gives useful information about bond strength.

Example:
In benzene (C₆H₆):

• Bond order = 1.5
• Bond strength is stronger than a single bond but weaker than a double bond

Thus:

Resonance increases stability by spreading electrons across multiple bonds, often increasing effective bond strength.

5. Molecular Orbital (MO) Theory Explanation

In molecular orbital theory, bond order is calculated by:

A higher bond order in MO theory means:

• More electrons are in bonding orbitals
• Fewer electrons are in antibonding orbitals

This increases the net attraction and results in a stronger bond.

Example:

• N₂ has bond order 3 → very strong bond
• O₂ has bond order 2 → strong but less than N₂
• Species with bond order 0 cannot exist because no bond strength is present

Thus, bond strength depends directly on bond order in MO theory too.

6. How Bond Strength Affects Reactivity

Bond strength determines how easily molecules undergo reactions:

• Strong bonds (high bond order) → low reactivity
• Weak bonds (low bond order) → high reactivity

Examples:

• N₂ (bond order 3) is very stable and unreactive
• O–O single bond in peroxides (low bond order) breaks easily → high reactivity

Thus, bond order helps predict chemical behaviour.

7. Exceptions and Special Cases

While bond order usually predicts bond strength accurately, some factors can modify this relationship:

• Lone pair repulsion can weaken bonds
• Large atoms may form weaker bonds even with higher bond order
• Resonance creates partial bonds that may behave differently

However, the general rule still holds:
Higher bond order = higher bond strength.

Conclusion

Bond order and bond strength are closely related. As bond order increases, more electron pairs are shared between atoms, creating stronger attraction and making the bond harder to break. This leads to higher bond energy and shorter bond length. Whether using basic bonding concepts or molecular orbital theory, the conclusion remains the same: higher bond order results in stronger, more stable bonds, while lower bond order leads to weaker bonds.