[wintermute]

Hi,

I may have stupid question, but I did not find anybody able to answer me yet.

In diamond, we have every single carbon attached to another four carbons. My question is: if we have carbon that is the part of the wall of crystal, I mean it is on the very boundary of the lattice, is it still bounded to four carbon in the neighbourhood? How this can be arranged in the space?

[AWK]

Good question. Usually, tentatively, hydrogen can be be placed to terminate bonds at boundary, but in fact this is unresolved problem.

[wintermute]

So, grinding the diamond leads to "oxidation" of environment (media, whatsoever)?

[Custos]

Yes. And cutting a diamond involves breaking strong covalent bonds by physical force.

[ARGOS++]

Dear ALL,

I’m sorry!  - Of course NOT!
Crystal Structure Forces are NEVER covalent Bondings, because otherwise chemical and physical properties of Diamonds would change with size and not only their PRICE!

Quintessence:   Surfaces AND Edges of the Crystal are CLEAN Carbon!
AND only the direction of the force and maybe its strengths are not identical to the other Carbons of the Crystal!!
But Forces inside the Diamond Crystal are anyway not all the same in all Directions!

Good Luck!
                    ARGOS⁺⁺

[Dolphinsiu]

What's meant by 'CLEAN carbon'?
I only know the diamond is made by laser cutting on the surface and edge so that the light can refract in the diamond in suitable manner!

[ARGOS++]

Dear Dolphinsiu,

“CLEAN Carbon” means, that there exist NO bondings/forces to any other atom/molecule or whatever, others than what normal Adhesion Forces may “catch”.
That’s not influencing LASER cutting in any way.

Good Luck!
                    ARGOS⁺⁺

[Dolphinsiu]

O I see. But how we make Clean carbon?
By complexing with CN-? or other way?

[ARGOS++]

Dear Dolphinsiu,


Oh!, - That happens automatically when you “form” the Diamond with a very high pressure from Carbon or Graphite, or when Mother Nature is doing (has done) it for you.
Most people call it “Re-Crystallisation”. The parameters for the process you may extract from the so called “Phase-Diagram” of Carbon.
The easier Way: "Search how Industrial Diamonds are made".

Good Luck!
                    ARGOS⁺⁺

[Valdorod]

Raymond Chang, the author of several books in genral, physical and industrial chemistry, current Professor at Williams College, as well as editor of the The Chemical Educator, states that Diamond is held by covalent bonds.  In his Book Chemistry 9th Edition, ISBN-13 9780073301709 he states, page 474.

"In covalent crystals, atoms are held together in an extensive three-dimensional network entirely bo covelent bonds.  Well-known examples are the two allotropes of carbon: diamond and graphite. In diamond, each carbon atom is sp3-hybridized; it is bonded to four other atoms.  The strong covelent bonds in three dimensions contribute to diamond's unusual hardness (it is the hardest material known) and very high melting point (3350 C)."

Valdo

[macman104]

Indeed Argos, my Inorganic book states as well that Diamond is a completely covalent compound.

[AWK]

Textbook are completely tru concerning stabilisation of covalent net, but the question of Wintermute was outside this problem which still is uresolved definitely.

[wintermute]

thanks, AWK

i still can't get the answer
obviously, hydrogen is the first think that comes to mind. but is it true? was any investigation carried out in this field?
i am sure it was.

[Borek]

was any investigation carried out in this field?

I suppose it was investigated - just the results are (so far) inconclusive.