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Re: [Phys-l] chemical bonds



JD,

I had a terrible intro chemistry course as an undergraduate - mostly empirical with lots of definitions and memorization. I did well in the course because I was adept at following patterns, but was frustrated because there seemed to be little to actually understand.

I am reading your presentation on the link you provided http://www.av8n.com/physics/draw-molecules.htm - it is an eye opener. I have also initiated a conversation with a very patient gas chemist here at Providence College who takes a physicist's approach to the chemistry. I wish I had come in contact with these ideas earlier.

Bob at PC

________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of John Denker [jsd@av8n.com]
Sent: Thursday, December 16, 2010 12:02 AM
To: Forum for Physics Educators
Subject: [Phys-l] chemical bonds

On 12/15/2010 09:24 PM, LaMontagne, Bob wrote:
Field lines come from and terminate on charges. What are the source
particles for "bonds"? Is there a difference between these stretchy
bonds and plain old electric fields?

The bond energy is partly the plain old electrostatic energy, but
also partly kinetic energy.

The kinetic energy contribution is not to be trifled with. Many
of the most basic, crucial things we know about atomic / molecular
physics (aka chemistry) could not possibly be explained by electric
fields alone. These include:
a) the fact that atoms have any nonzero size;
b) the fact that some bonds are directional;
c) etc. etc. etc.

Coulomb's law is spherically symmetric, so it could never explain
a directional bond. The nontrivial shape of everything from water
molecules to DNA molecules depends on having some directionality
to the bonds.
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