81 votes

Why can a diamond be broken using a hammer if it's the hardest natural substance known?

Hardness and toughness are not the same Hardness and toughness are very different qualities in materials and are weakly related. Hardness is strongly related to the more well-defined quantity of ...
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49 votes
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Are diamonds really forever?

how long would it take for this super-material to convert to the stuff I scribble with? No, despite the fact that James Bond said "Diamonds are Forever", that is not exactly the case. Although Bond'...
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33 votes
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Is buckminsterfullerene aromatic?

Aromaticity is not binary, but rather there are degrees of aromaticity. The degree of aromaticity in benzene is large, whereas the spiro-aromaticity in [4.4]nonatetraene is relatively small. The ...
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30 votes
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Why does diamond conduct heat better than graphite?

Diamond is one of the best thermal conductors known, in fact diamond is a better thermal conductor than many metals (thermal conductivity (W/m-K): aluminum=237, copper=401, diamond=895). The carbon ...
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24 votes
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Why does the image of cyclo[18]carbon look like a nonagon?

The first thing to say is that I'm not sure where that image is taken from; it's neither in the original article nor in the supporting information to the article. Therefore, it appears to be more of ...
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22 votes
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Why is the buckminsterfullerene the purest form of carbon?

Diamond has dangling bonds on the outer surface of the crystal for pretty much the same reason as graphite. If you understood graphite differently, then you understood it wrong. See, a molecule of ...
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  • 29.9k
21 votes

Why does diamond conduct heat better than graphite?

Ron's answer is great, but I'd just like to touch on the mechanisms behind thermal conductivity so we can rationalize the differences between the behaviour of diamond, graphite, and metals: There are ...
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21 votes
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Are graphite and hexagonal boron nitride aromatic

Graphite is definitely aromatic and boron nitride is at least partially aromatic. For instance, in this paper, the authors calculate the percent resonance energy (%RE) of graphite as a comparison to ...
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21 votes
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Why do diamond and graphite have different structures, when they are both composed of carbon?

Chemical structures are a tradeoff of several factors, including the conditions on how they were formed. The stability of any given chemical structure depends on the ease with which any specific ...
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19 votes

Is the valency of carbon satisfied in graphite?

In the hexagonal graphite structure the carbon atoms are $\ce{sp^2}$ hybridized, just like in benzene. In graphite, this p-orbital is used for bonding just as it is in benzene, resulting in an ...
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18 votes

Can diamond undergo a self sustaining combustion reaction all the way to carbon dioxide?

Yes, diamond will combust in air. Regardless of the ambient air temperature, e.g. your example of $21\ \mathrm{^\circ C}$, you of course have to heat it to it's ignition temperature somehow, whether ...
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16 votes
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What makes carbon special and versatile?

There are two key factors that account for the ubiquity of carbon compounds. Bond strengths: Look at the following table of bond strengths and notice how the strength of both carbon-carbon single and ...
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16 votes
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How small is the smallest known carbon ring containing only double bonds?

TL;DR: Isolated derivatives of cyclo-$\ce{C18}$ most likely have the smallest isolated cumulenic 18-membered ring, though upon direct complexation of transition metal in/outside the ring the strain as ...
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  • 35.1k
15 votes

Is buckminsterfullerene aromatic?

There are quite a few conjugated $\pi$-systems out there; some of them are pretty stable, some are less so. The ultimate way to find out is to go and solve the eigenvalues problem for the ...
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  • 29.9k
14 votes

Why can a diamond be broken using a hammer if it's the hardest natural substance known?

Diamond has cleavage planes. If you want something nearly unbreakable, try nephrite, which is a tough form of jade used by the ancient Aztecs to make axe heads! Actinolite is another related "tough as ...
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13 votes

Why is the standard enthalpy of formation of diamond not zero?

You are on the right track - diamond is not the thermodynamically stable carbon phase at STP. Taking two figures from A.T. Dinsdale, 'SGTE Data for Pure Elements', CALPHAD 15(4) 317-425 (1991) one ...
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13 votes

Why carbon nanotubes can act as a good electrical conductor?

I am sorry to say, but your question contains several false assumptions, most importantly: Nanotubes are good conductors: No, not all of them. Certain types have metallic/semi-metallic conductance, ...
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12 votes

Is graphite more stable than diamond?

At normal room temperature and pressure graphite is (slightly) more stable than diamond. But the melting point is not a good indicator of this. Melting points are determined by the bonding structure ...
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12 votes

Why can't one make C60 with a combination of hexagons and heptagons?

Well, let's see. This is not quite a chemical question, though I wouldn't recommend moving it to Math.SE either, because they might have hard time recognizing what's $\ce{C60}$. Now, let's imagine we'...
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12 votes

Calling Diamond an element?

It might be scientifically correct but it is linguistically misleading The sentence "diamond is an element" can be seen to be misleading when compared to the sentence "diamond is an allotrope of the ...
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11 votes
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Graphene Vs Copper?

The trick with graphene is that a lot of its amazing properties only work when you have continuous perfect sheets of it, and making graphene like this is currently beyond us, for large scales anyways. ...
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11 votes

Are graphite and hexagonal boron nitride aromatic

Yes, both graphite and borazine are aromatic in nature as each ring of a plane have six π-electrons (similar to benzene). This aromaticity explains why graphite and borazine are unusually ...
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  • 1,242
10 votes

Is graphite more stable than diamond?

This questions calls for an answer from thermodynamics. The figure provided above, lifted from here, is what we call a phase diagram. On the abscissa is temperature in units of Kelvin and on the ...
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  • 3,358
10 votes

If graphite's just a huge polymer of benzene why isn't it an aromatic compound (polymer?)

Graphite/graphene is aromatic. The first image below is a common crystallographic representation of graphite and does not account for covalent bonding. The second one shows the molecular structure of ...
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9 votes
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What's the type of bonding in La@C60?

That the question says: "Without any 'binding' forces, the atom couldn't be possibly trapped inside the fullerene", shows you are misunderstanding fullerenes. Atoms such as Helium and $H_2$ can be ...
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9 votes

Is turning graphite carbon into diamond industrially doable?

It has been done since 1954 and has been a commercial success for some time. Many products now have diamond-like coatings, produced comparatively inexpensively through vapor deposition without need ...
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8 votes
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What chemical substance is obtained by dissolving C60 in olive oil?

There is no chemical reaction between fullerene and olive oil, that is to say that the two molecules do not break or make chemical bonds to produce a new chemical species. However, fullerene is ...
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8 votes
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Is graphene chemically reactive?

Graphene in its pristine form, a single sheet of pure sp2 hybridized benzenes, is (relatively speaking) one of the least chemically reactive materials known because of several reasons: one, its ...
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  • 196
8 votes
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Structure of carbon fiber

The key difference between graphite and carbon fibers is the degree (or range) of ordering. In graphite there are large, extensive planes of carbon stacked one atop another resulting in long-range ...
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8 votes
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Why does graphite conduct electricity?

Carbon has four spare electrons. In graphite structure, two of them make two single (sigma) bonds while the other pair form a double bond (consists of one sigma and one pi bond). Electron that forms ...
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