Last Bullet Point of Outline 4

[Katie Lam 2J]

I am looking at the last bullet point of Outline 4 which states, "Describe the structure of a molecule, cation, or anion in terms of hybrid orbitals and sigma and
pi bonds." How do sigma and pi bonds affect the structure of a molecule, cation, or anion?

[Marc Lubman 3B]

Since a sigma bond involves end to end overlap of orbitals, it is a relatively bendy and mobile bond. Thus, molecules that have sigma bonds can usually rotate around those sigma bonds or bend them in certain directions. Pi bonds, on the other hand, involve side to side overlap of orbitals, and are thus rigid and immobile. So, a molecule with a double bond will not be able to move that double bond in any direction or rotate around it. If you're trying to determine the structure of a molecule with sigma and pi bonds, keep in mind that the pi bond (double or triple) is a rigid kink and cannot be moved into another position, and while sigma bonds can move and thus will move around to accommodate the most convenient shape of a molecule.

[Carlotta Gherardi 2J]

Hi,

If it can be of any help, I believe the professor will cover this in future lectures.

[305607822]

He has also talked about how pi bonds will break if the atoms rotate which means their electrons are more exposed and will be involved in more reactions.

[AashaK]

Pi bonds keep a molecule rigid and unable to rotate. So if there are double or triple bonds in a molecule, then the molecule is rigid and is not able to move or rotate. If one of the atoms involved in the double bond do rotate, then the pi bond will break. Sigma bonds, on the other hand allow for the atoms in a molecule to rotate, making it more flexible.