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Thermodynamics/splitting an atom??


An image I recall from a science textbook shows a grain of salt represented by a cube formed of blue and orange spheres representing sodium and chlorine atoms.

I can take a razor blade and cut a single grain of salt in half.  I am obviously not splitting an atom. And since the bonds between atoms are electrical, I suppose the bonds between molecules are, also.  Am I cutting electricity with a razor blade?  Probably not.  So what is it, exactly, that I am cutting?

This is not a prank question.  I'm 52 years old and this has been bugging me since fifth grade. An Internet search for the answer was unsuccessful.

Hi Jim,

Its a good question!

All models are wrong, some models are useful.

The spherical blue and orange atoms is a model of what a crystal of salt looks like if we could see atoms but we cannot. A grain of salt is a collection of crystals held together by much weaker forces than those that hold atoms together. They are known as Van der Vaals forces, a bit like static. Under pressure these weak forces are easily overcome (cut) and weaknesses in the grain (called fault lines or planes) will cause the grain to split.

I hope this helps.
Best wishes.


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Thermodynamics, chemistry, chemical reactions, kinetics, chemical reaction safety, dust explosion technology, static electricity. General science.


Over 40 years experience as a practicing thermochemist in industry. Head of the fire and explosion laboratory of a major European chemical company (Ciba-Geigy). Now retired.

Institute of Chemical Engineers. Royal Society of Chemistry.

Chartered Chemist, Member of the Royal Society of Chemistry (C.Chem MRSC). Msc Sheffield.

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