Just wondering, suppose you took a large rock and then somehow caused every single individual molecule that makes up that rock to suddenly disconnect from all of the others without a change in state, so that it’s still solid. Would this look like extremely fine sand, or would it act like a liquid, or would it be instantly blown away and constantly be floating in the wind, or something else?
If by “molecule” you mean a collection of atoms held together by covalent or ionic bonds, the molecules in rock can be quite large, with each grain of the rock being essentially a single molecule. I’d think fine powder would probably be it.
I have read there is a monoatomic helium powder that is distinct from liquid helium, but don’t have a cite.
The definition of “dust” has to enter into this, as dust particles and gas molecules both “condense”. By one definition, monomolecular dusts are liquids.
So, like, the boulder would become an aerosol?
Well, there are few molecules in your average rock. Rocks are generally made of ionic compounds, to use the Chem 101 phraseology. Large chunks of amorphous silica – a sloppy network solid, something like ice or diamond, only harder than the former and not nearly as hard as the latter – with Mg+2, K+, Ca+2 and some other metal ions thrown in. (We’re talking crustal rocks here; it’s different further down.)
So we can begin by rephrasing your question as: what would happen if all the chemical bonds in the rock were abruptly severed?
We still have to interpret that question, however. How exactly do we imagine that happening? The main part of the force of chemical bonding is quantum mechanical, and in essence it is a reduction in the kinetic energy of electrons due to the expansion of the volume within which they are confined by the attraction of nearby nuclei.
There are two ways, therefore, we can imagine cutting all bonds. First, we could imagine ruling out this quantum phenomenon, more or less by saying that there can be no “orbital overlap” – no way for electrons to gain more space by getting close to other nuclei. That happens already when the electrons are in the wrong spin state. It’s not possible to have *all * electrons in the wrong spin state for bonding – but let’s say we do.
In that case, the rock explodes. The reason is that there is also a pretty classical and very strong repulsion between atoms that comes from the electrostatic repulsion between their electron clouds. Ordinarily, the very strong chemical bonding forces overcome this, but if we get rid of the former…well then, clouds of electrons within a few 10s of pm of each other exert enormous repulsive forces on each other. Every atom in your rock would repel each other so hard you would have the world’s most powerful explosive, gram for gram. It might well outdo a nuclear explosion, inasmuch in most fission reactions only a small percentage of the fissile material actually fissions. Your rock would certainly turn into a fiendishly hot fireball of plasma immediately, and kill everyone within yards to miles, depending on the size.
There are other ways we could imagine getting rid of the chemical bonds, though. We could eliminate the exclusion principle, which is why their kinetic energy climbs so high on confinement anyway. Somehow turn all the electrons into bosons, or suspend Fermi-Dirac statistics for some reason. I think there are fundamental theories that argue that whether you’re a fermion or boson can be switched at sufficient energy.
In that case, your rock collapses. All the electrons fall to the lowest possible collective state, which greatly reduces the repulsion between atoms (which become smaller anyway). I have no idea what reduction in volume we can expect, but probably not that much – 20%? There’s no directionality in the interaction between atoms, so
you kind of have a very heavy liquid rock, with a sea of bosonic electrons and a lot of nuclei swimming among them fairly unhindered. The liquid heavy rock would have an enormous surface tension, however, so it would remain a sphere. The collapse would reduce the potential energy a lot, so we could expect a huge release of heat. You’d probably get a smaller, spherical, molten rock heated to a few tens of thousands of degrees. It would be white-hot.
What else? We could turn off the Coulomb force, in which case your rock turns into weird cold plasma of nuclei (held together by the strong force) and free electrons. However, the electrons then expand at about their typical orbital velocity (50,000 m/s). The nuclei are much slower, because they’re moving at 400 m/s or so. The expansion of the electrons, if we don’t turn off the Coulumb force between them and other objects, means once again you have a bomb. They’re very light, although moving very fast. Behind them you have the nuclei, which are moving much slower but much heavier. Either way, I’d say you get another bang.
Anyway, I don’t think we can figure a way to achieve this severing without a severly disruptive and promptly fatal event. The thing is, chemical bonding is a delicate balance between truly enormous forces. If you snip some of those forces, you get a wildly unbalanced system – not just a system freed of some constraint. Those unbalanced forces cause dramatic change.
Dry ice is a solid, with small non-polar molecules. Could one smash that down to separate molecules?
@Carl: Wow. That is… insightful, really, seems like my understanding of molecules left much to be desired. Thanks a ton for that info.
…However, mostly I’m looking for what a rocky substance would look like if crushed to the finest degree physically possible, not what our hypothetical separation method would result in.
So, instead of breaking down a rock, assembling one a the finest possible level?
As that amazing post by **Carl Pham **points out, it’s a lot of metals. Magnesium, calcium, potassium. Often as oxides.
So you’d get a fine metal dust, highly flammable, and a rush of oxygen, ready to oxidize some fine metal dust.
Edit- would it behave more like a dust or a liquid? No way to find out in an oxygen atmosphere, but perhaps under argon?
Isn’t buckmiminsterfullerene monomolecular dust? Or am I misunderstanding it?
What does it actually look like?
The Guinness did say solid helium could form mono-atomic particles but wasn’t clear about it: it might have been a theoretical mention, and not an actual observation.
I’ve seen carbon nanotube powder. It just looks like a black powder. It’s much lighter than you’d expect, though. TiO2 nanoparticles also look like white powder.
Solids are solid because there are strong bonds between the constituent molecules. If you break these bonds then what you have is no longer a solid.
Assuming your magic separation force could somehow stop the molecules instantly arranging themselves back into solid form after you’d separated them, then you’d have a gas. But in the absence of such a force, you’d just end up with a solid again, I imagine.