Sigma and Pi bonds questions

[905934067]

How do sigma and pi bonds contribute to the structural and shape characteristics of organic and biological molecules? Can you provide examples of how the presence and distribution of these bonds influence the overall geometry of molecules? This would help me so much in preparing for the final, thanks!

[Holly Hadsall 2H]

The main characteristic of a molecule that contributes to its overall geometry is the regions of electron density. So the number of sigma bonds effects this, however the number of pi bonds does not. In terms of a molecules structure, when two atoms are joined by a sigma bond they are flexible. However, because a pi bond involves the overlapping of p orbitals, these bonds are not able to twist and are less malleable.