**Ask a monkey a physics question thread**

[MadMojoMonkey]

I feel like states of matter are relatively arbitrary. I was taught in high school chemistry that glass is technically a liquid that flows unbelievably slowly, and that this could be observed in old houses, where the panes of glass are somewhat thicker at the bottom than at the top, due to creep.

I heard that before, too, but I don't think it's actually true.

Nope.

unlike the molecules in conventional liquids, the atoms in glasses are all held together tightly by strong chemical bonds. It is as if the glass were one giant molecule.

From: The 'glass is a liquid' myth has finally been destroyed

Is every solid somewhat amorphous like this, or is there some sort of boundary where a solid is truly solid and a liquid or amorphous solid is something different?

I think this is answered above. Let me know or restate it if not.

I would imagine that diamond is a solid in the purest sense of the word, so does it have something to do with having a crystalline structure?

A crystalline structure is definitely not a liquid, as the spacing and arrangement of the atoms defines the crystal. This is another "like a giant molecule" case, but it's really not, since the bonds are quite different

That feels iffy... I'm soft on chemistry, ultimately. (Is Chemist here?)

I know from a liquid to a gas there's a clear difference because gases can be compressed to change volume and liquids cannot.

It's all about the fact that in a gas there are no inter-molecular bonds because the kinetic energy of particle collisions is greater than the bonding energy.

In a liquid, there are weak inter-molecular bonds. In a solid, there are strong inter-molecular bonds.

Since the particles in a gas aren't bound together, they're not "touching", and there is space between them. So by compressing the volume, you're reducing the space between particles.

In liquids and solids, the atoms/molecules are bound to their neighbors already, so in order to compress them, you have to squish them closer together than they are. Quantum Mechanics has some stuff to say about that, and the reaction force rises rapidly with slight distortions.

I'll stop babbling.

How dare you, sir!