Rotation on the Internuclear Axis

[Ayesha Aslam-Mir 3C]

I'm a bit confused about the diagram of the pi bond forming on the internuclear axis that shows electron density on both sides of the internuclear axis. Doesn't the sigma bond also show electron density on both sides of the internuclear axis? Also, how are pi bonds formed then if not end to end. Lastly, how is the internuclear axis determined (what does it represent) and how would two atoms form both a sigma and pi bond?

[Anthony_3C]

Hi! The internuclear axis is defined as the straight line connecting the center of the two atoms in a bond. For your first question, the sigma bond does have electron density on both sides of the axis, but the density directly overlaps the axis, as seen in the image below. However, a pi bond is also an end-to-end line, but is located ABOVE and BELOW the sigma bond, which is what scientists mean when they say "electron density being on both sides of the internuclear axis". Therefore, a sigma bond and a pi bond can coexist since they don't touch each other. Hope this helps!

[Ayesha Aslam-Mir 3C]

Hi! The internuclear axis is defined as the straight line connecting the center of the two atoms in a bond. For your first question, the sigma bond does have electron density on both sides of the axis, but the density directly overlaps the axis, as seen in the image below. However, a pi bond is also an end-to-end line, but is located ABOVE and BELOW the sigma bond, which is what scientists mean when they say "electron density being on both sides of the internuclear axis". Therefore, a sigma bond and a pi bond can coexist since they don't touch each other. Hope this helps!

This is actually super helpful, thank you!