Molecular Orbitals: Carbon Nanotubes, Silicon & More

[mmwave]

While learning about carbon nanotubes I ran into the term molecular orbitals. I know something about atomic orbitals but took chemistry a long time ago.

I would expect the concept of molecular orbitals to be useful for covalent bonding like Silicon crystals and metals. I would expect it's not useful for Ionic bonding (the electron is transferred and that's that) nor for bonding like Van Der Waals. Is this right?

Since van der Waals bonding (like forces between liquid H2O molecules) don't involve electron sharing it's got nothing to do with molecular orbitals. Am I wrong?

Thanks.

 

[PeteGt]

You are correct.

Molecular bonding only occurs in a covalent system. In ionic systems these orbitals do not occur in the same fashion.

Watch what are you say :). It's hydrogen bonding between H20 molecules.

Even though intermolecular forces do not bond in any way to each other, they can affect the orbitals slightly.

This picture might help when thinking about orbitals. Forgive my bad handwriting.

Pete

 

[mmwave]

Originally posted by PeteGt

Watch what are you say :). It's hydrogen bonding between H20 molecules.

This picture might help when thinking about orbitals. Forgive my bad handwriting.

Pete

Thanks Pete.

I thought I heard 2 physicists and 1 physics book say liquid H20 was van der Waals forces. I check my notes and see what they really said.

Saddly, I am too ignorant to make much out of your drawing but thanks for trying. The handwritting is fine though.

A related question. In a Buckyball ( 60 atom spherical carbon molecule) the energy gap between Highest Occupied Molecular Orbital and the Lowest Unoccupied M. O. is 1.9eV.

What is this supposed to tell me?

 

[PeteGt]

Lol, that's okay. I figured it was kinda a big thing to put in front of you.

The Bucky Ball issue is nothing huge. 1.9eV would be a spectrum peak that would be detectable in the Visible spectrum. Thus easily identifiable. Other than that. Nothing really. Maybe that since 1.9eV isn't a major difference in M.O. then this molecule is uite stable.

Pete