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Questions tagged [states-of-matter]

Physicists classify matter according to the state of matter, which are gas, liquid and solid. A material is either in one of these states depending on the temperature and/or pressure applied to it. One characterises the state of matter by the mechanical response of a material under pressure.

Most of the characteristics of the states of matter can be understood using thermodynamics. Gas can be deformed without volume constraint under pressure. Liquid can be deformed with conservation of volume under pressure. Solid can not be deformed under pressure.

Modern condensed matter theory is concerned with much more states of matter than just the three classical ones. The reason is of course that quantum physics offers much more interaction than classical physics. Interactions between charges and/or spins lead for instance to plasma (metal) or magnetic ordering, and can not be understood without quantum formalism.

Note that the classification between all the states of matter is rather informal, and still under debate, especially for the quantum phases.

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Why does matter exist in 3 states (liquids, solid, gas)?

Why does matter on the earth exist in three states? Why cannot all matter exist in only one state (i.e. solid/liquid/gas)?
Kiran Kumar
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Why does ice melting not change the water level in a container?

I have read the explanation for this in several textbooks, but I am struggling to understand it via Archimedes' principle. If someone can clarify with a diagram or something so I can understand or a clear equation explanation that would be great.
stackseverywhere
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If liquid and gas are both chaotic states of matter, what's the difference between them on the molecular level?

I'm a laywoman in physics and recently found myself pondering about the matter reflected in the title of this post. To make my question more precise from the mathematical standpoint, let's suppose you are given a 3D image of the momentary positions…
Mitsuko
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Why is Helium so hard to liquify?

By the end of the 19th century all gasses had been liquefied apart from helium (He). What is it about helium that makes it so hard to liquefy compared to the other gases? And why does it need to be pre cooled in the Joule-Kelvin expansion?
Quantum spaghettification
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At what temperature are the most elements of the periodic table liquid?

For elements where 'liquid', is relatively easy to define, at which temperature are the most elements liquid, and which ones? Assume 1 atm
yolo
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Is helium liquid at 0 K?

I just saw in the dynamic periodic table that He is liquid at $-273.15\ ^\circ \rm C$. Is that true? How is that even possible? Can someone explain?
Christina Melita
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Why, exactly, does temperature remain constant during a change in state of matter?

My counterargument: Intermolecular forces between molecules are either intact or broken. There is no in-between. Therefore, the change from intact to broken is instantaneous. Applied heat energy increases the movement of particles in a substance,…
Raen
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Why does a critical point exist?

I still cannot fully comprehend the essence of a critical point on phase diagrams. It is usually said in textbooks that the difference between liquid and gaseous state of a substance is quantitative rather than qualitative. While it is easy to…
xaxa
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What is a state in physics?

What is a state in physics? While reading physics, I have heard many a times a "___" system is in "____" state but the definition of a state was never provided (and googling brings me totally unrelated topic of solid state physics), but was loosely…
Manish Kumar Singh
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Freeze water in red-hot container

While reading Edgar Allan Poe's short story The thousand-and-second tale of Scheherazade (about a fantastic journey to the present of 1850) I once stumbled on the following footnote to the phrase "Another made ice in a red-hot furnace": Place a…
Anon
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Why do ice crystals form from the top to the bottom of a bottle filled with supercooled water?

If I bang a bottle filled with supercooled water against a hard surface, the ice crystals form from the top to the bottom:$\hspace{50px}$$\hspace{75px}$–source. YouTube has videos showing this effect: 1; 2; 3; 4; 5. Question: Why don't the ice…
panda
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Why does water ($\mathrm{H_2O}$) only have two distinct fluid phases?

Water (and other substances) can exist in many distinct solid phases (with different crystallic micro-structure), but only in two fluid phases - liquid and gaseous, in which the molecules are oriented randomly (they is no long range order). Is there…
Ján Lalinský
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Is play-dough liquid or solid?

At room temperature, play-dough is solid(ish). But if you make a thin strip it cannot just stand up on it's own, so is it still solid? On a more general note, what classifies or differentiates a solid from a liquid?
Ayman
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Does any substance melt or evaporate when cooled at constant pressure?

Is there any substance with segments of its phase change diagram lines going in a negative direction? To explain: Generally, as phase change diagrams go, with heat increasing, and pressure constant, substances tend to evaporate, sublimate or melt;…
SF.
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If we repeatedly divide a solid in half, at what point does it stop being a solid?

Suppose I have some material in solid-state (say), I cut it into two parts. Take the first cut it into two parts, take the first cut it into two parts, and then repeat this again and again. There will be a point when the substance loses its solid…
Himanshu
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