Bond length of lower element having single bond formed because , they have low intermolecular force of attraction , but they are formed sigma bond ( strong bond ) .

Bond lengths are lower in elements having Triple Bond

Bond length is defined as the distance between the nuclei of two bonded atoms. The bond length varies depending on the type of bond, such as single, double, or triple bond. In general, the bond length decreases as the bond order increases. Therefore, in elements having triple bonds, the bond length is lower compared to single or double bonds.

Explanation:

Triple bonds involve the sharing of three pairs of electrons between two atoms. This results in a stronger bond than a double bond or a single bond. The stronger bond in a triple bond pulls the two atoms closer together, resulting in a shorter bond length.

For example, the bond length of the carbon-carbon triple bond in acetylene (C2H2) is 1.20 Angstroms, while the bond length of the carbon-carbon double bond in ethylene (C2H4) is 1.33 Angstroms. Similarly, the bond length of the nitrogen-nitrogen triple bond in nitrogen gas (N2) is 1.10 Angstroms, while the bond length of the nitrogen-nitrogen double bond in nitric oxide (NO) is 1.15 Angstroms.

In addition to bond order, bond length also depends on factors such as electronegativity, atomic radius, and hybridization. However, in general, the bond length decreases as the bond order increases.

Conclusion:

In conclusion, the bond lengths are lower in elements having triple bonds. This is because triple bonds are stronger than single or double bonds, resulting in a shorter distance between the two bonded atoms.