Pi bonds vs sigma bonds (1 Viewer)

[Run hard@thehsc]

Why are subsequent pi bonds easier to break than sigma bonds?

 

[someth1ng]

There is less orbital overlap in pi bonds than sigma bonds. Essentially, the electron density in sigma is directly between the two atoms so it's better at keeping the two atoms together.

 

[qwertywerido]

I got told that the pi bonds are easier to break because their shape was more 'open to attack'.

 

[Run hard@thehsc]

Fair. Can someone recap me briefly on what bond breaking actually does? I have just been taught that breaking bonds need energy and thats all!

 

[someth1ng]

Fair. Can someone recap me briefly on what bond breaking actually does? I have just been taught that breaking bonds need energy and thats all!

I'm not sure exactly what the HSC requires. However, bond breaking in most reactions involves either removing electrons from a bonding orbital or adding electrons to the antibonding orbitals.



For homolytic cleavage, the energy increase (e.g. light breaking a bond), you'd end up with it going back to the atomic orbitals (i.e. diradical)

I got told that the pi bonds are easier to break because their shape was more 'open to attack'.

The pi bond is weaker because of less orbital overlap which results in a lower bond dissociation energy (i.e. less stabilised by bonding). If you look at the first diagram, the pi bond is higher energy (i.e. bonding is less stabilising) than the corresponding sigma bond (which is lower in energy).