Re-thinking molecules

A C Richards said:
When Heat its applied to steel it will freely share some of it's atoms or even molecules. Carbon is shared and runs along the bounderies creating the carbides needed to have a hard edge. This is were the difference between molecule and crystal come into play. The carbon is in a free form resting in the spaces between the molecules of the steel. It does not actually "combine" with the molecule but rather slide along and take up space. As the "crystal"/"molecule" changes with heat the carbon moves around to fill the voids left behind. This is where we get carbon diffusion between High and Low carbon layers in a damascus billet. Other alloying elements do not move as freely mostly due to size.

This is how I ?understand? it and may be way out in left field, not an unfamiliar place.
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Chuck, if you heat mayonnaise it can break it too.

At room temperature, the carbon gets trapped, and becomes part of the martensite molecule/crystal, right?... or is the carbon not considered part of the molecule?

I wonder what happens at absolute zero, in a Bose-Einstein condensate?

I have no idea where this is going,... but it is interesting, no? :D
 
As far as I know absolute zero doesn't extist in nature or reality,... but is just a "concept".

Have you ever heard a scientist try to explain a Bose-Einstein condensate?
They say the atoms lose their identity,... or some such thing.

Bose-Einstein condensate:
A phase of matter in which all bosons in a given physical system have been cooled to a temperature near absolute zero and enter the same quantum state.
 
Bose-Einstein condensates are basically another form of matter. Bose-einstein condesnates, solids, liquids, gasses, plasmas. Pretty wierd stuff. It has been made frequently in laboratories, but I doubt if it would exist anywhere else, even in space, as it would have to occur so far into the outer reaches away from any source of heat (so as to get one smidge above absolute zero) that the vaccume of space would destroy it. In this state, the material is so cold that it basically can't get any measurably colder (ie....is absolute zero even possible to achieve....not likely as there are an infinite number of decimal places to get through before zero). In other words, even things like friction don't hold effect any more becuase friction gives off energy, and that can't happen. This alows it to do some wierd stuff like defy gravity and climb the walls of its container, etc.

--nathan
 
It is true that bose-einstein condensates exist in the laboratory at ~nano kelvin temperatures, but that absolute zero is impossible to obtain.

It's hard to explain exactly what it is though if you have not had a decent quantum and statictical mechanics course, which is probably why most scientists sound goofy when they try to describe it.

greg
 
In general, Molecules are the simplest bonded units of a compound or element. Ionic bonds form when one atom loses electron(s) to another and they stick together by electrostatic forces. Covalent bonds form by sharing outer shell electrons ans are generally stronger than ionic ones. Metallic bonds form where the electrons are all held in common by the material and may flow (in conduction) in response to energy input. This makes it difficult to define a molecule-one might say the whole mass is a molecule of metal.

Adding heat will alter some bonds easier than others and new ones may form. Crystalline material will respond to thermal input (if high enough) by recrystallizing (annealing, for instance) or by changing to a different phase as in the Pearlite to Austenite transition. Sudden cooling may form a quench marterial like glass or Martensite that is not really a phase. These quench states are metastable in that over significant amounts of time they will tend to revert to a stable phase.
 
gregorio said:
It is true that bose-einstein condensates exist in the laboratory at ~nano kelvin temperatures, but that absolute zero is impossible to obtain.

It's hard to explain exactly what it is though if you have not had a decent quantum and statictical mechanics course, which is probably why most scientists sound goofy when they try to describe it.

greg
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Bose-Einstein condensates raise a lot of questions. They aren't gas, liquid or solid, and from what I gather they don't exist in nature or the universe,... outside of a few laboratories.

I was listening to one scientist trying to explain them in layman’s terms, and it went something like this (as far as I remember): in a Bose- Einstein condensate from the same element, the atoms lose their identity and form, but that's not all,... not only do they not know what they are, they also don't know “where” they are within the Bose-Einstein condensate that they are part of. They all become part of the same quantum state.
 
Steve Hayden said:
In general, Molecules are the simplest bonded units of a compound or element. Ionic bonds form when one atom loses electron(s) to another and they stick together by electrostatic forces. Covalent bonds form by sharing outer shell electrons ans are generally stronger than ionic ones. Metallic bonds form where the electrons are all held in common by the material and may flow (in conduction) in response to energy input. This makes it difficult to define a molecule-one might say the whole mass is a molecule of metal.

Adding heat will alter some bonds easier than others and new ones may form. Crystalline material will respond to thermal input (if high enough) by recrystallizing (annealing, for instance) or by changing to a different phase as in the Pearlite to Austenite transition. Sudden cooling may form a quench marterial like glass or Martensite that is not really a phase. These quench states are metastable in that over significant amounts of time they will tend to revert to a stable phase.
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I was thinking something along those lines.

Time seems to be a big factor in all of it, as well as heat or the lack of it...
 
a quick search on wikipedia results in:

In chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two atoms in a definite arrangement held together by strong chemical bonds.[1][2] In organic chemistry and biochemistry, the term molecule is used less strictly and also is applied to charged organic molecules and biomolecules. Molecules are distinguished from polyatomic ions in the strict sense.

This definition has evolved as knowledge of the structure of molecules has increased. Earlier definitions were less precise defining molecules as the smallest particles of pure chemical substances that still retain their composition and chemical properties.[3] This definition often breaks down since many substances in ordinary experience, such as rocks, salts, and metals, are composed of atoms or ions, but are not made of molecules.
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Don't shoot the messenger...I am not a scientist...at best, a wiki-est. :D
 
silver_pilate said:
Bose-Einstein condensates are basically another form of matter. Bose-einstein condesnates, solids, liquids, gasses, plasmas. Pretty wierd stuff. It has been made frequently in laboratories, but I doubt if it would exist anywhere else, even in space, as it would have to occur so far into the outer reaches away from any source of heat (so as to get one smidge above absolute zero) that the vaccume of space would destroy it. In this state, the material is so cold that it basically can't get any measurably colder (ie....is absolute zero even possible to achieve....not likely as there are an infinite number of decimal places to get through before zero). In other words, even things like friction don't hold effect any more becuase friction gives off energy, and that can't happen. This alows it to do some wierd stuff like defy gravity and climb the walls of its container, etc.

--nathan
Click to expand...

I thought that absolute 0 was when it is so cold that atoms stop moving, and has nothing to do with "it can get no colder". So it can be achieved. As far as I know anyway...which isn't much.

-Mike Sheffield
 
I thought that absolute 0 was when it is so cold that atoms stop moving, and has nothing to do with "it can get no colder". So it can be achieved. As far as I know anyway...which isn't much.
Click to expand...

That's partially true, but is it possible for matter to demonstrate absolutely no emitted energy (i.e. stops moving). If it is, then is it really possible to go colder than absolute zero?? As far as anyone I know knows, no. (like that last alliteration there :D) Absolute zero is an absolute. It can go no colder. It's also theoretical because as far as we know, it exists nowhere in the universe and would be impossible to achieve in any way we know of. It is a theoretical point where there is no emitted energy. Remember, temperature is just another way to measure the energy output of a system.

--nathan
 
More accurately, temperature is the net kinetic (not necessarily output) energy of a system. Not is related to, not influences... it IS. So, if everything stops moving, how could you have any less movement, i.e. temperature?

Sorry, my nerdy pedanticness showed through for a bit there.
 
"Absolute zero" is attained in your stomach after you eat some of Tai's heated mayonnaise.
 
Here's what dictionary.com says:

absolute zero
–noun the temperature of −273.16°C (−459.69°F), the hypothetical point at which all molecular activity ceases.

absolute zero
n. The theoretical temperature at which substances possess no thermal energy, equal to -273.15°C, or -459.67°F.

noun
(cryogenics) the lowest temperature theoretically attainable (at which the kinetic energy of atoms and molecules is minimal); 0 Kelvin or -273.15 centigrade or -459.67 Fahrenheit


absolute zero
The lowest possible temperature, at which all molecules are have the least possible amount of kinetic energy. Absolute zero is equal to 0°K, -459.67°F, or -273.15°C. At temperatures approaching absolute zero, the physical characteristics of some substances change significantly. For example, some substances change from electrical insulators to conductors, while others change from conductors to insulators. Absolute zero has never been reached in laboratory experiments. See also Bose-Einstein condensate, zero-point energy.

The temperature of a substance is determined by the average velocity of its molecules: the faster they move, the warmer the substance. At absolute zero molecules have minimal kinetic energy (or zero-point energy) and heat energy cannot be extracted from them. The molecules are not motionless, however, due to the uncertainty principle of quantum mechanics, which entails that the atoms cannot have both a fixed position and zero momentum at the same time; instead, the molecules of a substance at absolute zero are always "wiggling" in some manner. Absolute zero is zero degrees Kelvin, equal to -273.15 degrees Celsius and -459.67 degrees Fahrenheit. The coldest known place in the universe is the Boomerang Nebula, where the temperature is -272° Celsius. Scientists at Massachusetts Institute of Technology have gone much lower than that by using laser traps and other techniques to cool rubidium to 2 × 10-9 degrees Kelvin.
 
when you look at steel you see what everyone talks about. Small portions, grains, of crystalline order seperated by grain boundaries. It is doubtful you would see anyting as clean as the pic of gold in sffar's link because of the extreme measures taken to produce their samples.

I work in a lab with some atomic force microscopes that have tens of nanometer resolution.
 
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