What's On The Edge Of A Diamond?

I realise it's a crystal lattice, but the diagrams merely show the edges going on forever, how diamonds have fixed shapes, what happens at edges? Surely there aren't just carbon bonds floating around.

Gilgamesh is everywhere THEREFORE Gilgamesh is at the edges (modus tollens) QED

but I wanna know :(

I have no idea, so I'm just going to speculate wildly.
Its probably some kind of different bonding pattern at the surface, like the thing water molecules do that create surface tension.

Hydrogen bond? With the carbons?

At the scale you're talking about, if the edge is 10 atoms wide and looks rather square, it would still be one of the sharpest edges in the macro-world that you've ever seen.  Is this question of yours really relevant to curiosity?

I think he's just asking what happens when you have a sheet of crystal and crack it in half, do some of the crystal patterns get disrupted or just end normally

yeah, a perfect diamond would be a single macromolecule with each carbon atom bonded to four other carbon atoms.  when you run out of carbon atoms, the diamond stops, and presumably there would be unsatisfied carbon atoms not bonding to four partners.  maybe they bond to whatever is avaliable, or if nothing is available, could uneven bonding make for a bit of deformation?

I don't know for sure, but I speculate that some combination of the following is happening:
a) incomplete bonds stay incomplete/carbon somehow gain extra bonds with its neighbors
b) surface carbons are bonded to atmospheric contaminants (transiently or otherwise) (eg aluminum gains a protective oxide coating)
c) surface carbons are changing into graphite since diamond is not thermodynamically stable at STP

Some info mentioned here: http://www.molecularassembler.com/Papers/PathDiamMolMfg.htm
(Slide 11, 12, 26 and 27 most relevant.)

The illustrations seem to suggest a outer layer of hydrogen atoms, but 'dehydrogenated' diamond is also mentioned, where again we must assume either free electrons (unstable) or a different structure that connects the carbon at the surface.

>>10
Oh wait, it's written right there, under slide 27. A dehydrogenated surface has dangling bonds. It can be connected to more carbon, or passivated with hydrogen atoms.

dangling bonds, a new phrase for me to enjoy

4tran, help me out here.  If your option "c" was true, then a microscopic portion of the diamond would transform from the hardest substance to the softest.  Even being so small, that soft substance could be abraded off.  That leaves danglers, which become more graphite, and then the process repeats.  That suggests that diamonds would disintegrate into graphite (or graphite flaws destroy the diamond).  That doesn't seem to happen with diamonds that are worked (as industrial diamonds in drill bits, etc.) such that they would reveal such a process.

how does a diamond surface hydrogenate?  Is it a reaction with water vapour?  So is water broken down, giving us oxygen?

>>13
First, I admit I'm not sure exactly how diamonds change to graphite over time, but it does happen, and takes millions of years (can't find data at the moment).

Given anything, if you abrade it long enough, it will _eventually_ disintegrate.  Every time you use that diamond drill, some carbon atoms are falling off.  I claim that this process is far faster than the transition to graphite (continuous abrasion will destroy a diamond long before a million years).  As a result, most of the carbons close to the surface will get rubbed off long before they get a chance to turn to graphite.

A diamond changing to graphite is merely a rearranging of their bond structure. This kinda thing happens precisely because of surface arrangements, and it doesn't happen just with diamonds, but any kind of macromolecule relying on a repetitive pattern.

I do molecular simulations of some of these crystals, and every time before we calculate collisions, etc, we "relax" the crystal. We know what the general "unit cell" of the crystal looks like, but not at all how it'll be arranged at the surfaces, so we let the system relax, each atom moving under the forces pushing it back and forth, and ultimately they form strange shapes; a rectangular crystal might become pseudo-circular at the boundary, or with more pinched edges, you never really know.

I can only speculate that with diamonds, given the ease of bonding of carbon atoms, there's a lot of contamination from environmental residue.

I did some googling and it seems that graphite transformation of diamond is far too slow to ever worry about.  I had my suspicions about what was happening to the "loose" electrons as #16 described, but I don't have the education in that area to have reached a conclusion.  Thanks, #16.

Recent research is showing us that the molecular world is a lot more chaotic than previously imagined (at least by laymen).  Water forms many molecular structures, which makes me wonder if microwave-heated water is really different than convection-heated water, inasmuch as Human consumption is concerned.

>>17
its more delicious.

>>16
Does the inside of the crystal structure remains stable?

>>16, 17
Thanks.

>>17
which makes me wonder if microwave-heated water is really different than convection-heated water, inasmuch as Human consumption is concerned.
*sigh* You're useless. Water forms many SOLID molecular structures. You can't form molecular structures in a liquid. Also, MICROWAVE PARANOIA, tinfoil hat time. Aside from boiling your food, microwaving it is by far the safest way to cook food because you don't get any carcinogens from grilling or frying it.

>>13,15
That doesn't seem to happen with diamonds that are worked (as industrial diamonds in drill bits, etc.) such that they would reveal such a process.
Actually they do. That's why they still sell diamond needles for old record players; the needles get worn out through heavy use and have to be replaced.

Your original assessment is flawed anyway; much more than the top layer of diamond is lost in a drill pass. Fun math time, diamond has a density of 3.5 g/cm^3, carbon 12 g/mol => there are 1.76e+23 carbon atoms per cubic centimeter of diamond. If only the top layer of carbon were transformed to graphite and seared off in each drill pass, it would still take more than the age of the universe to run through a drill bit.

I'm sorry, #20, but it's not paranoia -- just a musing.  And you're also wrong about the structures water forms in liquid form.  Experiments have found long-lasting chains of water molecules, as well as other structures (clumps, mostly).  Since water is a polar molecule, that it would form temporary structures in liquid form is not surprising; what surprised me is the longevity.  You can google around a bit yourself.

I do have a friend who does subscribe to the "microwaved food and water are unhealthy" set.  I keep urging her to obtain proof of those assertions.  However, it's not rational to AVOID wondering if microwaves do cause unhealthy chemical changes.  It remains for experimenters to seek in those directions; certainly I can't perform any such experiments here for direct testing ... I'd have to use the model of clinical trials with myself as the sole subject.  Not only does the latter have serious reliability flaws, but I don't want to find out such information in that fashion.

For the record, I do have a microwave and I do use it on occasion to re-heat food and water.  The installed base of microwave cooking strongly suggests that any harm it does is either too low to care about, or too long term to reliably detect.  And as a final note, when microwaving, I keep away from the unit; there's no reason to trust the unit's shielding more than I absolutely have to.  After all, if the shielding should fail and microwaves start caramelizing the humors of my eyes (for example), what real warning would I have before my vision began to blur (permanently!)?

>>which makes me wonder if microwave-heated water is really different than convection-heated water

yes microwave heated water is more random in nature

>>21 your eyes have humor?

>>20
Looks like jump to conclusions tiem.

>>20,21
With regards to the liquid water thing, these guys claimed to have discovered a new type of liquid water.  I don't know how accurate their assessment is, but they've been around for a while.  I used to recall a mini science section with moar details on the matter, but I can't seem to find it.

http://www.pentawater.com/faq.shtml#Pentapatented

>>21
I've learned to not attempt heating water with microwaves; it takes way too long.

If it's really intense leaking, you might experience immediate vision loss/blurring.  If it's less intense, you might be unable to open your eyes when you next wake up.  Sounds tramatizing, but I recall the damage to the corneas being temporary.

>>23
http://en.wikipedia.org/wiki/Aqueous_humour
http://en.wikipedia.org/wiki/Vitreous_humour

I googled quickly and arrived resultantly at the wiki for it:

http://en.wikipedia.org/wiki/Penta_Water

Right off the bat, I have to ask what contamination is introduced into the water by "subjecting [it] to high energy sound waves".  As you know, water bubbles that energetically form bubbles and then collapse is very abrasive, so all this sonic action in any container would likely abrade the contain and this contaminate the water.

Thanks for the info on Penta Water.  I had great fun reading the wiki.  Apparently, from making too many fraudulent statements about their snake oil, the Penta folks are currently off the net.

You know, there is a way of doing some informal but fairly reliable testing of "types" of water, based upon preparation.  Pot 3 sets of 3 plants each from the same seedstock or cuttings.  Place them in the same environment, and water them precisely with the following:

1. cooled-down water that was boiled on the conventional stove
2. cooled-down water that was boiled in the microwave
3. tap water

Use 3 plants in each set to obtain average behavior.  Make sure the pots are absolutely clean to begin with, and of course use the same batch of well-mixed soil from a reliable source.

Getting back to diamonds...

Empty sp3 orbitals?

Or maybe its some type of sp2 orbital so that the face is flat.

lol iunno

<(0_0)>

I'd imagine that since it isn't in a vacuum it would bind to a small amount of atmospheric particulate on the surface, or the carbons could be double bonding.

>>26
Good point about their treatments adding in their own contaminants.

Tap water varies quite a bit by geographic region, so the experiment can lead to different results.

>>27
Probably not totally empty; since all the orbitals can support 2 electrons, they will probably be half filled.

>>13
Dude. Graphite is soft because the LAYERS are weakly linked. Your theoretical SINGLE graphite layer - or (depending on the cleavage angle) a bunch of graphite layer-ends, all tightly held in the lattice - wouldn't sof'n down the dimond the least bit.

Also, graphite needs terminating hydrogens or stuff too (tho fullerene looping wouuld work some of the time.)

Don't call me gay, but I need some mary jay!

Marijuana MUST be legalized.