Re-thinking molecules

Two or more atoms comprising a small stable chemical structure such as O2, H2O, etc. That's my chemistry days speaking for me! :-)
 
Molecules are one of the fundamental units forming a chemical compound; the smallest part of a chemical compount that can take part in a chemcial reaction. In general, molecules are held together by covalent or coordinate bonds.

It's easy to confuse molecules with ionic compounds, which do not have single molecules; rather, they are collections of oppositely charged ions. Many people often see a molecular equation, such as NaCl, and assume it's a molecule, when it's often an ionic compound.

It's also easy to confuse covalent structures that forum macromolecular crystals, which have no discrete molecules - essentially, the entire crystal forms a molecule.


Why do you ask? Do you have a specific question regarding something of a chemistryish nature?

Take care,
Brook
 
Correct me if I'm wrong, Tai, but I believe the question stems from recent semantic debates about the microscopic structure of steel and its tranformation into various forms: austenite, martensite, pearlite, bainite, etc.

Crystals, molecules, body-centered cubics, face-centered cubics, cementite, grains, itsy-bitsy tiny little mystical fairy gnomes who work hard to magically pack the grains of steel into a tighter substance during the incredibly tightly controlled process of forging..... you know, the basic stuff. :D

--nathan
 
Tai,
Better watch out asking these deep questions. That molecule in your head may heat up and burn out.:D:D:D;););):D:D:D
 
Silver pilate, now you reminded me ! Those tiny little fairy gnomes -they use nano carbon buckie balls to play soccer !!
 
Steel is an alloy (or any metal alloy) An alloy is a homogeneous mixture or metals. A solid solution. Meaning that the ingredients are not chemically combined, just dissolved into each other. They still have their individual chemical properties and can be separated by ordinary means. Alloys are determine by the size of the metal atom and how they fit together. Do you want me to go deeper?
 
I was wondering about the mayonnaise molecule? Is it the teeny tiny itsy bitsy droplet of oil,... or is it the teeny tiny itsy bitsy droplet of oil surrounded by an even smaller film lemon juice?

... molecule meaning: The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms; a group of like or different atoms held together by chemical forces.
 
zman308 said:
Steel is an alloy (or any metal alloy) An alloy is a homogeneous mixture or metals. A solid solution. Meaning that the ingredients are not chemically combined, just dissolved into each other. They still have their individual chemical properties and can be separated by ordinary means. Alloys are determine by the size of the metal atom and how they fit together. Do you want me to go deeper?
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No. That does it for me.
Thank you.
 
zman308 said:
Steel is an alloy (or any metal alloy) An alloy is a homogeneous mixture or metals. A solid solution. Meaning that the ingredients are not chemically combined, just dissolved into each other. They still have their individual chemical properties and can be separated by ordinary means. Alloys are determine by the size of the metal atom and how they fit together. Do you want me to go deeper?
Click to expand...

The carbides in steel are molecular. They share the outer shell electrons with the metallic bond, but the carbide itself has a strong covalent/weak ionic bond. The weak ionic nature of the bond allows the outer electrons to partake in the metallic structure of the overall material.

Some alloying elements are in solid solution in the steel, but others, mainly transition metals form carbides until available Carbon is used up.
 
Steve Hayden said:
The carbides in steel are molecular. They share the outer shell electrons with the metallic bond, but the carbide itself has a strong covalent/weak ionic bond. The weak ionic nature of the bond allows the outer electrons to partake in the metallic structure of the overall material.

Some alloying elements are in solid solution in the steel, but others, mainly transition metals form carbides until available Carbon is used up.
Click to expand...

So then you saying that steel does have molecules in it.
 
bjalongi said:
It's also easy to confuse covalent structures that forum macromolecular crystals, which have no discrete molecules - essentially, the entire crystal forms a molecule.
Click to expand...

So you seem to be saying that the crystals themselves are the molecules.

... or maybe that the simplest smallest possible crystal is the molecule... is that correct?
 
If the carbides in steel are molecular and the crystals are molecular,... then isn't the steel itself molecular?

If that’s true why don’t metallurgist like the word "molecule" or term "molecular level"?

… just curious?
 
A crystal at it's base is a molecule forming in a very specific manner, Diamonds are cubic crystals that form from the carbon atom.
 
Tai Goo said:
So you seem to be saying that the crystals themselves are the molecules.

... or maybe that the simplest smallest possible crystal is the molecule... is that correct?
Click to expand...

This basically refers to single large crystaline structures, such as a diamond - atleast as far as I understand it from what I learned in college chemistry. Sorry for the confusion. I'm sure the metalurgists on this site have more insite into the crystaline structures that occur in alloys.
 
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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