## Difference between sigma and pi bonds?

$sp, sp^{2}, sp^{3}, dsp^{3}, d^{2}sp^{3}$

Daniel Rivas 3L
Posts: 32
Joined: Fri Sep 29, 2017 7:07 am

### Difference between sigma and pi bonds?

I am a little confused on what the difference is and how each of them forms. Does it have to do with shape or with how the electrons interact when bonded?

Stephanie tran 1J
Posts: 50
Joined: Fri Sep 29, 2017 7:04 am

### Re: Difference between sigma and pi bonds?

sigma and pi bonds are associated with the electron density and how the electrons interact with each other. A sigma bond is formed by the pairing of electron spins in two atomic orbitals on neighboring atoms. sigma bonds are cylindrically symmetrical and they contribute towards an overlap or merging of atomic orbitals and an accumulation of electron density between nuclei of two atoms. pi bonds, on the other hand, are formed when electrons in two atomic orbitals pair and overlap side by side. A pi bond has electron density on each side of the internuclear axis. The electrons lie in two different lobes rather than one like in a sigma bond.

104754311
Posts: 13
Joined: Fri Sep 29, 2017 7:06 am

### Re: Difference between sigma and pi bonds?

A sigma bond can also be associated with a single bond whereas a pi bond can be a double bound.

Yifei Wang 3G
Posts: 19
Joined: Fri Sep 29, 2017 7:07 am

### Re: Difference between sigma and pi bonds?

Stephanie tran 1H wrote:sigma and pi bonds are associated with the electron density and how the electrons interact with each other. A sigma bond is formed by the pairing of electron spins in two atomic orbitals on neighboring atoms. sigma bonds are cylindrically symmetrical and they contribute towards an overlap or merging of atomic orbitals and an accumulation of electron density between nuclei of two atoms. pi bonds, on the other hand, are formed when electrons in two atomic orbitals pair and overlap side by side. A pi bond has electron density on each side of the internuclear axis. The electrons lie in two different lobes rather than one like in a sigma bond.

Can you explain what "side by side" means when describing the pi bond?

804899546
Posts: 51
Joined: Sat Jul 22, 2017 3:00 am

### Re: Difference between sigma and pi bonds?

I know you can have multiple pi bonds, but can you have multiple sigma bonds? In all of our examples it seems that there is only ever one sigma bond.

Matthew 1C
Posts: 47
Joined: Fri Sep 29, 2017 7:06 am

### Re: Difference between sigma and pi bonds?

804899546 wrote:I know you can have multiple pi bonds, but can you have multiple sigma bonds? In all of our examples it seems that there is only ever one sigma bond.

You can have multiple sigma bonds if you're counting bonds in a molecule, say for example a molecule has a single bond and a double bond, then there are two total sigma bonds. But when looking at double or triple bonds, only one is a sigma and the other one/two are pi bonds.

Irma Ramos 2I
Posts: 51
Joined: Fri Sep 29, 2017 7:07 am

### Re: Difference between sigma and pi bonds?

sigma bonds allow bound atoms to rotate which allows them to have electron density with cylindrical symmetry around the internuclear axis, while pi bonds don't allow for rotation of bound atoms which explains the electron density on each side of internuclear axis