End-to-end vs. Side-to-side

[Chloe Thorpe 1J]

So I know that sigma bonds are end-to-end and pi bonds are side-to-side, but what exactly does this mean? What does are we refering to when we say “end-to-end”?

[Dong Hyun Lee 4E]

When you draw out the different orbitals (S,P,D,F) for different atoms, thhe orbitals will overlap with each other. Since the s orbitals would overlap horizontally, they would be considered overlapping end to end, while the p orbitals which reach out vertically from the atom would interact side by side with each other. Looking at the oribtals on paper and drawing them out and seeing which orbitals they interact with will help alot.

[Mariam Baghdasaryan 4F]

Professor Lavelle drew the p-p orbitals on the board which helped me visualize this. Note that a p-orbital has 2 lobes. For the "end-to-end," if p-orbital 1 and p-orbital 2 are in the horizontal direction next to each other, the "end" of the right lobe of p-orbital 1 will "overlap" with the "end" of the left lobe of p-orbital 2. Now imagine these two p-orbitals vertically. The top lobe of p-orbital 1 will "overlap" on the "side" with the top lobe of p-orbital 2, and the bottom lobe of p-orbital 1 will "overlap" with the bottom lobe of p-orbital 2.