Pi bond concepts

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Kevin Tang 4L
Posts: 83
Joined: Fri Sep 28, 2018 12:28 am

Pi bond concepts

Postby Kevin Tang 4L » Tue Nov 27, 2018 4:29 pm

I don't seem to fully grasp the concept of pi bonds. I understand that double bonds have one sigma and one pi and that triple bonds have one sigma and two pi bonds. Pi bonds also cannot rotate because of its orientation, it extends out perpendicular down, and up and then connect.

What I don't understand is why it extends out upwards and downward. It feels like one pi bond consists of two bonds, not one. If I am missing some concepts on pi bonds, please let me know.

Thank you.

Anushi Patel 1J
Posts: 61
Joined: Fri Sep 28, 2018 12:19 am
Been upvoted: 1 time

Re: Pi bond concepts

Postby Anushi Patel 1J » Tue Nov 27, 2018 4:37 pm

Each p orbital has two "lobes" that extend in opposite directions. So the parts of the bond that extend up and down are actually between 1 set of p orbitals.

ThomasLai1D
Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

Re: Pi bond concepts

Postby ThomasLai1D » Tue Nov 27, 2018 4:37 pm

The shape of a single p-orbital has the shape of a dumbbell. In a pi bond, one "head" of the dumbbell extends upwards, and the other extends downwards. The upward head interacts with the upward head of the other atom and the downward head corresponds with the downward head of the other atom, which is why it seems like it should be two bonds.

Henry Dudley 1G
Posts: 61
Joined: Fri Sep 28, 2018 12:16 am

Re: Pi bond concepts

Postby Henry Dudley 1G » Fri Nov 30, 2018 5:59 pm

Pi bonds overlap side by side with sigma bonds preventing them from rotating.

Karishma_1G
Posts: 67
Joined: Fri Sep 28, 2018 12:18 am

Re: Pi bond concepts

Postby Karishma_1G » Fri Nov 30, 2018 6:17 pm

Pi bonds are formed between two p orbitals that are perpendicular to the internuclear axis. For this reason, the two p orbitals overlap above and below the internuclear axis and cannot rotate. If you have the 7th edition of the textbook, Figure 2F.4 on page 118 is helpful for visualizing this bond.


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