Carbon bonding in graphite

[laser1]

Homework Statement

Describe the C-C bonding in graphite

Relevant Equations

N/A

My lecture notes says it is $\sigma + \frac{\pi}{2}$. Why is it not $\sigma + \frac{\pi}{3}$? As each electron from every carbon is shared between 3 C-C bonds

 

[mjc123]

I agree with you. Benzene has 6 pi electrons and 6 C-C bonds. Graphite has 6 pi electrons and 9 C-C bonds per 6 C atoms. You can draw 3 resonance structures; each bond is double in 1 structure and single in 2.

 

[laser1]

I agree with you. Benzene has 6 pi electrons and 6 C-C bonds. Graphite has 6 pi electrons and 9 C-C bonds per 6 C atoms. You can draw 3 resonance structures; each bond is double in 1 structure and single in 2.

Yeah that was my reasoning too. Probably just a typo. Thanks for confirming!

 

[DrDu]

This is a difficult question! The p_z orbitals do not only have bonding interactions with neighbouring atoms but also interact with the neighbouring bonds. If one assumes a perfect pairing quinoid structure, the pi system would be non-bonding.

 

[laser1]

This is a difficult question! The p_z orbitals do not only have bonding interactions with neighbouring atoms but also interact with the neighbouring bonds. If one assumes a perfect pairing quinoid structure, the pi system would be non-bonding.

Oh. I assume that my notation sigma + pi/2 etc. stuff is just a very simplified representation of it?