# Carbon to Carbon Bonds on the Surface of a Diamond **URL:** \ **Category:** Factual Questions\ **Created:** [March 14, 2023, 4:25pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175 "2023-03-14T16:25:27Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Ynnad](https://avatars.discourse-cdn.com/v4/letter/y/4491bb/32.png) [@Ynnad](https://boards.straightdope.com/u/Ynnad)\ **Post date:** [March 14, 2023, 4:25pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/1 "2023-03-14T16:25:27Z")
I have another question about diamonds that might have a factual answer. In a diamond crystal, each of the carbon atoms it covalently bonded to four other carbon atoms in a tetrahedral shape. But what about carbon atoms on the surface of the crystal. How are the bonds of these surface atoms configured? Wouldn’t it have to be something other than a tetrahedron? One might speculate about configurations on the corners and points of a cut diamond. I would suggest that if you “look” closely enough at these corners and points you would discover that they are actually just curved surfaces. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 14, 2023, 4:52pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/2 "2023-03-14T16:52:03Z")
I’m between meetings. Start here: > **[Dangling bond](https://en.m.wikipedia.org/wiki/Dangling_bond)** > > In chemistry, a dangling bond is an unsatisfied valence on an immobilized atom. An atom with a dangling bond is also referred to as an immobilized free radical or an immobilized radical, a reference to its structural and chemical similarity to a free radical. > When speaking of a dangling bond, one is generally referring to the state described above, containing one electron and thus leading to a neutrally charged atom. There are also dangling bond defects containing two or no electrons. These are ... Depending on how that satisfies or causes confusion, I or someone else can follow up. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 14, 2023, 5:29pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/3 "2023-03-14T17:29:17Z")
ISTM the answer will depend on at what orientation you cut the surface, how the surface subsequently reconstructs itself, adsorption of atoms like hydrogen, etc. E.g. > **[Structure of the diamond (111) surface: Single-dangling-bond versus...](https://journals.aps.org/prb/abstract/10.1103/PhysRevB.53.13725)** > > We present converged first-principles calculations for the atomic and electronic structure of diamond (111) surfaces based on density-functional theory in the local-density approximation. Single- and triple-dangling- bond surfaces with... (there are figures with various views of atoms at the reconstructed surface, to be compared with the bulk structure) ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [March 14, 2023, 5:58pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/4 "2023-03-14T17:58:29Z")
Wasn’t Dangling Bond a porn James Bond parody? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 14, 2023, 8:15pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/5 "2023-03-14T20:15:58Z")
> The groups on the surface of diamond include epoxide, carbonyl, carboxylic and hydroxyl. I don’t have access to the paper on this device, so I’m not sure what the coverage is. [https://doi.org/10.1016/0301-7516(82)90029-1](https://doi.org/10.1016/0301-7516(82)90029-1) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 14, 2023, 10:00pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/6 "2023-03-14T22:00:15Z")
Yeah, I’d expect that the surface would just have various non-carbon impurities bonded on. An atom-thick layer of impurities would go completely unnoticed. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 15, 2023, 5:52am UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/7 "2023-03-15T05:52:28Z")
> [@Ynnad](#): > > But what about carbon atoms on the surface of the crystal. There’s a reason that crystals are shaped in ways that resemble their lattices or some arrangement of their lattices. It’s precisely to minimize any non-bonded atoms - in a “perfect” crystal, you’d just stack the unit shapes so that they repeat endlessly. But in diamond, a “perfect” crystal like that isn’t possible at the surface. So what happens is that the surface structure of a diamond more closely resembles graphite. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 15, 2023, 10:33am UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/8 "2023-03-15T10:33:37Z")
> [@MrDibble](#): > > So what happens is that the surface structure of a diamond more closely resembles graphite. “Resembles” as in bond length? Bond order? Orientation? ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 15, 2023, 11:08am UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/9 "2023-03-15T11:08:24Z")
Bond length and type - it’s what happens when you take a \<111\> slice through the diamond lattice, it’s like a single layer of graphite. Orientation isn’t meaningful here - the \<111\> diamond orientation isn’t the \<100\> orientation of graphite so it doesn’t translate. Now, in most (natural) diamonds, there’s also going to be oxygen bonded at that surface. That’s what renders diamond hydrophobic. There’s stuff you can do to diamonds to change that property, essentially doping just the surface with other substances. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 15, 2023, 11:42am UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/10 "2023-03-15T11:42:43Z")
> [@MrDibble](#): > > Bond length and type - it’s what happens when you take a \<111\> slice through the diamond lattice, it’s like a single layer of graphite. [![](https://pubs.rsc.org/image/article/2020/mh/c9mh01588d/c9mh01588d-f3_hi-res.gif) ](https://pubs.rsc.org/image/article/2020/mh/c9mh01588d/c9mh01588d-f3_hi-res.gif) A vs B. A diamond 111 surface is not like single layer of graphite, not in bond length, bond order, or reactivity. From: [The surface hybridization of diamond with vertical graphene: a new route to diamond electronics - Materials Horizons (RSC Publishing)](http://xlink.rsc.org/?DOI=c9mh01588d) ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 15, 2023, 11:44am UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/11 "2023-03-15T11:44:23Z")
What part of “more closely resembles” did you read as “exactly identical to”, pray tell? ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 15, 2023, 1:12pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/12 "2023-03-15T13:12:34Z")
“more closely resembles” is incorrect. The surface of diamond resembles the interior, with dangling bonds that can be populated by various species. The OP specifically asked about how the bonds of surface atoms are configured. They are not configured in a way that more closely resembles graphite. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 15, 2023, 1:54pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/13 "2023-03-15T13:54:43Z")
> [@Ruken](#): > > “more closely resembles” is incorrect. Then don’t publish pictures that show different. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 15, 2023, 9:10pm UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/14 "2023-03-15T21:10:26Z")
> [@MrDibble](#): > > Now, in most (natural) diamonds, there’s also going to be oxygen bonded at that surface. That’s what renders diamond hydrophobic. > Although as-grown H-terminated diamond surfaces are highly hydrophobic, they become hydrophilic after oxygen-plasma treatment. Water contact angle measurements were carried out for both as-deposited and polished diamond surfaces. These were 91.0 and 62.7°, respectively, but changed to 0.6 and 20.5° after oxygen plasma treatment for 1 minute. [https://doi.org/10.1016/S0022-0728(99)00027-3](https://doi.org/10.1016/S0022-0728(99)00027-3) ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [March 16, 2023, 4:55am UTC](https://boards.straightdope.com/t/carbon-to-carbon-bonds-on-the-surface-of-a-diamond/981175/15 "2023-03-16T04:55:37Z")
You’re right, hydrogen, not oxygen.