Sigma and Pi

[Matia Kim 1B]

Why is the first bond always going to be Sigma? and the second and third Pi? can there be more than 3?

[Sarah Zhao 4C]

First bond will always be sigma because they need to have a sigma bond in order for the electrons to be oriented in a way to form a pi bond.

Yes there can be more than 3 bonds but that gets complicated and I'm assuming we don't need to know it for this chapter.

[Karan Thaker 2L]

Pi bonds always form after the formation of a sigma bond, so that is why we always say sigma bonds form first.

[Schuyler_Howell_4D]

The reason you can't have two sigma bonds is because of the orientation of the regions of electron concentration. There is always electron repulsion and since a pi bond can't have a rotation, the atoms/ molecules are locked in a specific position. Once a pi bond is used, the following bonds have to also be pi bonds. (Remember the example Prof. Lavelle used with the markers falling out of his hand)

[Kyither Min 2K]

Sigma bonds are first because without sigma bonds, pi bonds wouldn't form. You can only have one sigma bond because the orbitals have to be the right spin and attraction to hybridize into sigma bonds and the pi are the other orbital hybridizations.

[JT Wechsler 2B]

Sigma bonds must occur first before a pi bond will form. This has to do with the orientation of the electrons in the bonding pairs.