# Liquid or Solid?

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Glass, is it a liquid or solid. You always hear that glass is always melting, and when you look at old works of glass, you notice the bottom is thicker then the top. Its really not defined either way. I searched it on google.com, but no define answer for it.

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http://math.ucr.edu/home/baez/physics/General/Glass/glass.html

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There is no clear answer to the question "Is glass solid or liquid?". In terms of molecular dynamics and thermodynamics it is possible to justify various different views that it is a highly viscous liquid, an amorphous solid, or simply that glass is another state of matter which is neither liquid nor solid

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I would say that its an amorphous solid. It flows as if a liquid, however it is certainly doesnt fit the definition-

liquid-

A substance in the fluid state of matter having no fixed shape but a fixed volume.

You can shape glass into a form, though it will flow over time.

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What about a fiber optic cable then?

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HEY!!! hows it going? Why is metal not clear? Why is liquid metal not clear? Why is ice clear? I have heard that glass is clear because it is an extreemly viscous liquid, but is ice only a really viscous liquid? If being a liquid is the one magical requirement for being clear than why is liquid metal not clear? I have also hear that it is the fact that metal has many free electrons which reflect light that make it opaque. Would this not mean that liquid iron with no electrical charge would be clear?

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There is no clear answer to the question "Is glass solid or liquid?". In terms of molecular dynamics and thermodynamics it is possible to justify various different views that it is a highly viscous liquid' date=' an amorphous solid, or simply that glass is another state of matter which is neither liquid nor solid[/quote']

Yes there is a clear answer. Glass is an amorphous solid, as opposed to a crystalline solid. Glass transitions are different than crystalline ones.

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According to what I learnt in school, glass is a "super-cooled liquid". That explains the "flow" of glass.

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"HEY!!! hows it going? Why is metal not clear? Why is liquid metal not clear? Why is ice clear? I have heard that glass is clear because it is an extreemly viscous liquid, but is ice only a really viscous liquid? If being a liquid is the one magical requirement for being clear than why is liquid metal not clear? I have also hear that it is the fact that metal has many free electrons which reflect light that make it opaque. Would this not mean that liquid iron with no electrical charge would be clear?"

Wow, someone went hyperactive. j/k

Being "clear" (or transparent) is usually because the electrons don't have free energy levels to rise, and then to drop down from to emit light, as you have heard.

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Being "clear" (or transparent) is usually because the electrons don't have free energy levels to rise, and then to drop down from to emit light, as you have heard.

If thats true then I think you have in essence answered all the questions you posed.

Metals have typically free energy levels for electrons to jump to. Glass being the 3-d covalent solid it is, its hard to imagine free energy levels in there. The example that pops up in my mind as soon as I think about this question is diamond v/s graphite. Excellent example because it illustrates that transparency is not inherent in atomicnumber or molecular structure but also in the spatial arrangement of the same. But that would also have me believe, that in theory it should be possible to create some sort of structure with metal atoms as well that should yield transparency - this could very well happen when metal is beaten into extremely thin sheets. As far as liquid metal is concerned, I don't know if you have ever seen any first hand -I think everyone should- but when its liquid all you see is red or yellow, hard to say at that stage wether it is opaque or transparent, even glass that hot would glow. I must say thus that I am not truely convinced that all liquid metals will be opaque.

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According to what I learnt in school, glass is a "super-cooled liquid". That explains the "flow" of glass.

It's not. The "glass flowing" stuff is not credible - it's an urban legend. Glass just doesn't undergo the same transition, so you don't get the same indications about when it's a solid or liquid.

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"this could very well happen when metal is beaten into extremely thin sheets."

Yes it indeed does, a good example is a nanosheet of gold.

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glass, OLD glass will indeed shift towards gravity as a liquid may, it is however

an amorphous solid !

its not actualy a TRUE solid in the way of a structured Crystal is.

Pitch is similar, if left hung up, it will drip every 10 years or so, it also is an Amorphous solid and will shatter when struck like glass.

Add another term to your thinking, there is Solid and Liquid, and Amorphous solid

its not quite as Black and White as would be convenient

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glass, OLD glass will indeed shift towards gravity as a liquid may

Here is more on the subject.

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glass' date=' OLD glass will indeed shift towards gravity as a liquid may, it is however

an amorphous solid ![/quote']

I've seen old glass that was bottom-heavy because of the manufacturing process, but I've seen even older glass that was not in the least distorted.

I need a bit more than "it's an amorphous solid", because that's what everyone says. Giving something a name and providing an example of something that shares that name (along with the attribute that is being queried) is not really an explanation.

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no probs, think of a TRUE crystal, Sodium Chloride for example (NaCl).

its a cubic crystal with a very distinctive and structured placement of the Na and Cl atoms.

in Glass, although the Molecule is intact, it lacks the same sort of Structure, hence it doesnt make the transition between solid and liquid as does a molten solid, with glass thwe molecules "slide" over and around each other, in a structured solid this isnt possible until in a molten state.

with glass and added heat these "sliding" molecules can move more freely and thus it has no particular transition temperature.

hope that helps ya a little?

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All the other explanations I have seen (incl. the link swansont posted) make out that glass being an amorphous solid - and its particular properties - make the "glass is a liquid" claim an urban myth, particularly since it doesn't actually flow.

Amorphous in this context simply means that there is no long-range order in the structure, not that there is no fixed shape.

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All the other explanations I have seen (incl. the link swansont posted) make out that glass being an amorphous solid - and its particular properties - make the "glass is a liquid" claim an urban myth' date=' particularly since it doesn't actually flow.

Amorphous in this context simply means that there is no long-range order in the structure, not that there is no fixed shape.[/quote']

it CAN actualy "flow" at different temps, as well as being extruded under pressure(s) even at room temp. fact is gravity is a minor force that takes almost centuries before evident.

theres no fixed shape of a Crystal, the molecles intact 100%, but theres no particular "Order" in which these molecules may rest (or indeed move).

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While they have properties in common, glass is not a crystal - crystals have long range order. It's also important to note that all glasses are amorphous, but not all amorphous substances are glasses.

Linerally paraphrased from:

Feltz, A. (1993) Amorphous Inorganic Materials and Glasses. VCH Verlagsgesellschaft mbH, Weinheim/VCH Publishers, New York, 446 pp. ISBN 3527284214/1560812125.

This is most useful:

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Thank you Gilded and Pulkit for answering my question. You are the frist people able to do so.

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No problem Spike. :> Glass always reminds me (because of its funny structure) of black opals. Little silicon dioxide balls that have a few water molecules in them.

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My uncle is one the few hand glass blowers around. The shop he works for puts out some really nice stuff. I have heard many differ things about glass, so I was just seeing what kind of answers I would get. Its one of those thins I guess, just on its one.

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Uranium glass-things are ace. Especially marbles are nice, just make sure you don't lose them! Being a glassblower is truly a marvellous profession. Who wouldn't like a blowjob?

*Warning! Excess amount of stupid jokes in one post... Emergency shutdown...*

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glass' date=' OLD glass will indeed shift towards gravity as a liquid may, it is however

an amorphous solid !

its not actualy a TRUE solid in the way of a structured Crystal is.

Pitch is similar, if left hung up, it will drip every 10 years or so, it also is an Amorphous solid and will shatter when struck like glass.

Add another term to your thinking, there is Solid and Liquid, and Amorphous solid

its not quite as Black and White as would be convenient [/quote']

Glass is actually a liquid of extremely high viscosity. Heavy glass panes standing for a long time have benn noticed to increase thickness at the bottom. A liquid, in my old days, was defined as a material with short length order, a solid, as one with long distance order. But notice that a crustal can also creep.

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Glass is actually a liquid of extremely high viscosity. Heavy glass panes standing for a long time have benn noticed to increase thickness at the bottom. A liquid, in my old days, was defined as a material with short length order, a solid, as one with long distance order. But notice that a crustal can also creep.

No. It's an amorphous solid.

What is the point of having threads if nobody is going to read them before they post?

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