CHEMISTRY COMMUNITY

Can someone explain to me why single bonds are weaker than double bonds which are weaker than triple bonds? Shouldn't single bonds be the strongest?

Single bonds are the weakest because they are the longest. Double and triple bonds are stronger because they are smaller and held tighter to the atoms.

Another way to look at this that might make more sense is that in a double bond two pairs of electrons are shared between atoms whereas a single bond has only one shared pair of electrons. With more electrons shared, the atoms have to pull closer together and are more 'dependent' on staying bonded with each other to have their outer shells filled.

Strength of a bond is measured by its' dissociation energy (the energy required to break a bond)

the longer the bong the weaker it is, this is because if the bond length is longer it is easier to break

There are more electrons involved with double and triple bonds, which pulls the atoms closer together and contributes to bond strength.

Single bonds are the weakest because the valence electrons with which the bonds are made are at the greatest distance, and so there is less attraction between the nucleus and the electrons. As distance increases, the force of attraction between any two objects decreases.

In a less scientific way, it is easier to break a thin stick that is about 6 feet long (a single bond) rather than a stick that is 3 centimeters long (a triple bond). Hence, single bonds are weaker than double or triple because they are longer.

Note, the chosen lengths are arbitrary.

As previous posters have made clear, single bonds are typically longer and weaker, while double and triple bonds are each shorter and stronger. I think the strength of single/double/triple bonds also has to do with the lone electron pairs, however. In a single bond, for example, you will typically have unbonded pairs of electrons in close proximity to one another, making the bond less stable and weaker. Alternatively, in a triple bond, you will likely have a single lone pair on each atom, facing outwards, thus not weakening the strength of the bond. I may be wrong however, but I think this is how it works.

Single bonds are the weakest since only one electron pair is being shared. Thus, the force of attraction between the nucleus and the shared pair is low. However, with double bonds, the area of electron density is much more dense/strong since more number of electrons are being shared and thus the force of attraction between the nucleus and the shared pair is stronger. Consequently, the double bond is also shorter. The same can be applied to explain why triple bonds are even stronger than double bonds.