## Sigma and Pi bonds

Hannah Pham 1D
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

### Sigma and Pi bonds

How do we figure out if i bond is a sigma bond or a pi bond?

klarratt2
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

### Re: Sigma and Pi bonds

A single bond is a sigma bond. A double bond is a sigma bond plus a pi bond. A triple bond is one sigma and two pi bonds.

A sigma bond is a basic covalent bond, with the bond in line with the bonding orbitals. You can only ever have one sigma bond between any two atoms.

A pi bond is a covalent bond between orbitals perpendicular to the bond direction, usually p-orbitals (never s). The resulting bond is roughly shaped like two croissants with the tips touching at the bonded atoms. Pi bonds do not allow rotation around the bonding axis due to this geometry.

A second pi bond (the third bond in a triple bond, or a second double bond to another atom) is always perpendicular (orthogonal) to the first one. In other words, if the sigma bond is on the x axis, one pi bond will form between orbitals on the y axis and another will form between orbitals on the z axis.

Aurbal Popal
Posts: 63
Joined: Fri Sep 28, 2018 12:27 am

### Re: Sigma and Pi bonds

A single bond has a sigma bond.
A double bond has both a sigma bond and a pi bond.
A triple bond has one sigma bond and two pi bonds.

Sigma bonds can happen between s and s orbitals, p and s orbitals, or s and p orbitals. The orbitals overlap end to end.
Pi bonds usually just happen between p orbitals. The orbitals overlap side to side.

Bianca Barcelo 4I
Posts: 74
Joined: Fri Sep 28, 2018 12:17 am
Been upvoted: 1 time

### Re: Sigma and Pi bonds

What are the purposes of sigma and pi bonds? Do they just create a bigger area for electron movement?

Emily Ng_4C
Posts: 65
Joined: Fri Sep 28, 2018 12:17 am

### Re: Sigma and Pi bonds

Bianca Barcelo 1G wrote:What are the purposes of sigma and pi bonds? Do they just create a bigger area for electron movement?

I believe sigma and pi bonds give you a more specific visual representation of how two atoms/molecules bond. For instance, sigma bond is where they bond at one point, and a pi bond is where they bond at multiple points.

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