# How big is a diamond molecule? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 13, 2023, 1:31pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108 "2023-03-13T13:31:37Z")\ **Posts on this page:** 11\ **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 13, 2023, 1:31pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/1 "2023-03-13T13:31:37Z")
How big is a diamond molecule? I put this question in **IMHO** and not **FQ** because I believe any response will be more like an opinion than a fact. ---
**Author:** ![Si\_Amigo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/si_amigo/32/2877_2.png) [@Si\_Amigo](https://boards.straightdope.com/u/Si_Amigo)\ **Post date:** [March 13, 2023, 1:35pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/2 "2023-03-13T13:35:43Z")
I beleive that your premise is inaccurate as a diamond is not a singular molecule, but a molecular structure of carbon molecules. Perhaps more accurate to discuss crystal size. ---
**Author:** ![keeganst94](https://avatars.discourse-cdn.com/v4/letter/k/a6a055/32.png) [@keeganst94](https://boards.straightdope.com/u/keeganst94)\ **Post date:** [March 13, 2023, 1:53pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/3 "2023-03-13T13:53:49Z")
If the diamond is a single crystal, then the whole thing is one molecule. All of the carbon atoms are connected together via covalent bonds. That might seem weird, but there are lots of arbitrarily large macromolecules. Rubber, for example, can be one extensively cross-linked molecule. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [March 13, 2023, 2:05pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/4 "2023-03-13T14:05:43Z")
I think it a debatable issue whether it’s more sensible to call it one huge molecule or just to say it’s not molecular. Can you have a mole of white dwarfs? [https://www.nationalgeographic.com/science/article/diamond-the-size-of-earth](https://www.nationalgeographic.com/science/article/diamond-the-size-of-earth) ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 13, 2023, 2:35pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/5 "2023-03-13T14:35:35Z")
Diamond, of course, has a crystalline structure, but it makes perfect sense to look at a single cubic cell of this structure and measure the length of a side: 3.57 Å, which seems pretty small considering it is not a close-packed structure, compared to silicon (5.43), germanium (5.66), tin (6.49) in the carbon group. ---
**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 13, 2023, 2:35pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/6 "2023-03-13T14:35:45Z")
Crystalline solids are not what I’d call molecular. Carbon can form monoatomic molecules - buckminsterfullerene is molecular, for instance. But diamond and graphite are not. Simple test - can you tell me the mass of a mole of diamond? _Not_ a mole of carbon, mind you. A mole of diamond. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [March 13, 2023, 3:02pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/7 "2023-03-13T15:02:13Z")
> [@MrDibble](#): > > Simple test - can you tell me the mass of a mole of diamond? Assuming it’s life-sized, about 3.5x the mass of a regular mole. 😃 ---
**Author:** ![don\_t\_ask](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@don\_t\_ask](https://boards.straightdope.com/u/don_t_ask)\ **Post date:** [March 14, 2023, 12:40am UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/8 "2023-03-14T00:40:19Z")
As big as the Ritz. ---
**Author:** ![Projammer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/projammer/32/559_2.png) [@Projammer](https://boards.straightdope.com/u/Projammer)\ **Post date:** [March 14, 2023, 5:23am UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/9 "2023-03-14T05:23:08Z")
Allow me to attempt to restate the OPs question then. How large is the smallest collection of carbon atoms that would be identifiable as a diamond? My quick search indicates it would be this structure (not to scale). [![](https://www.tf.uni-kiel.de/matwis/amat/iss/kap_4/illustr/diamond_1.png) ](https://www.tf.uni-kiel.de/matwis/amat/iss/kap_4/illustr/diamond_1.png) ---
**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 14, 2023, 5:42am UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/10 "2023-03-14T05:42:44Z")
> [@Projammer](#): > > How large is the smallest collection of carbon atoms that would be identifiable as a diamond? That was already answered: > [@DPRK](#): > > 3.57 Å That’s the [lattice constant](https://en.wikipedia.org/wiki/Lattice_constant) for diamond. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [March 14, 2023, 12:31pm UTC](https://boards.straightdope.com/t/how-big-is-a-diamond-molecule/981108/11 "2023-03-14T12:31:54Z")
Natural diamonds have impurities in them, so the molecular definition of “diamond” is imprecise. (Most artificially-made diamonds, being much more pure, react differently to UV light.)