sigma and pi bonds

[Rebekah L - 3k]

What does the textbook mean when it says that a sigma bond had no nodal planes containing the internuclear axis? And what does it mean when a pi bond has a single nodal plane containing the internuclear axis? What is a nodal plane and what is a internuclear axis? Can someone explain like they're talking to a 4th grader.

[Brian Huynh 2L]

Remembering back to the wave function a nodal plane is an area where the probability density of electrons is 0. Just looking at the orbitals themselves, the s orbital is symmetrical (it is a circle) meaning it has NO nodal planes (there is a high probability density that electrons can be found anywhere within the circle). On the other hand, p orbitals are dumbbell shaped (looks like an infinity sign) a nodal plane is that region in the middle that separates the two circles- there is a probability density of 0 in finding electrons in this region.

Sigma bonds do not have nodal planes because the atoms with sigma bonds can rotate, therefore, electrons can basically end up any where. However, in pi bonds (MADE UP OF P ORBITALS, which are described above as having nodal planes) the atoms CANNOT rotate, which is why there is 2 discrete electron dense regions separated by a nodal plane right through the middle. And I think that the internuclear axis is just referring to an imaginary axis that the bonds belong on. This axis allows us to illustrate the rotation of sigma bonds and the inability for pi bonds to rotate.

I hope this helps