Why is a single bond the longest bond?
1 Answer
It comes down to the number of shared electrons that create the electron density between the two nuclei. The greater the amount of charge in the region between the nuclei, the shorter the bond.
Explanation:
To compare apples to apples, you should consider single, double and triple bonds between the same two elements - such as the C to C bond in organic compounds.
While a single bond forms through the sharing of one pair of electrons between the atoms, a double bond involves twice as many electrons. The greater number of electrons that are spending time between the nuclei of the two atoms, the stronger the force these electrons exert on the nuclei and the closer together the nuclei are drawn before attractions and repulsions balance in a stable bond.
A triple bond goes this even one better, with three pairs of bonding electrons occupying the region between the nuclei.
